Updated 27 Feb 1999

Amateur Astronomer's Notebook

Amateur Astronomy Questions and Answers


Amateur Astronomer's Notebook has received quite a number of astronomy related questions from people all over the world. Questions are personally answered by either Peter Chapin or Joe Roberts. We have noticed that many of the questions are similar ("I can't see anything in my Tasco telescope... why?"). So, to help visitors, this page will now serve as a collection of questions and answers in the hopes that readers may find some useful information.

Important: It is our policy to protect the privacy of all people who send us e-mail. Therefore, all questions published on this page are stripped of any and all information that might reveal the identity of the author.

Do you have a question about some aspect of amateur astronomy? E-mail us here. I try to answer any question for which I am qualified to do so.

I have made an attempt to try to organize some of the questions on this page. Organizing them in a way that allows one to search for topics does not seem to be an easy task. Nonetheless, I have made a first attempt to do so. Each question has a topic listed to help you locate specific topics. You can also use your browsers "find" feature to help locate certains words. Question and answer categories appear below:

Question Categories

Questions and asnwers have been indexed into the following categories:

Tasco Telescope Q+A

TOPIC: Fixing up a Tasco telescope


I recently bought a Tasco telescope (model # 302012: D=114mm, F=900mm). Included in this bargain were a HM25mm lens that is the best of the bunch but it doesn't seem to focus too well and puts halos and shadows around objects. The package also included a H20mm lens, a SR4mm lens and a 2X Barlow lens (which seems to be of very poor quality). I was not pleased with the telescope. I didn't know if the telescope was garbage or if the lens' were crappy. Can you give me some information on where to go from here? Do I use this telescope as a planter or tire chalk and start again? Will better lens' remedy the problem? (If so, any suggestions on what to buy?) I can't in good conscience sell this to somebody else so I am looking for options that include keeping the body of the scope if that's possible. Thanks for your time and I look forward to hearing from you.


First, thanks for taking the time to write to AAN. As I was reading it, I thought to myself "oh no, not another person being discouraged by a Tasco telescope..."

The reason the views are cloudy and not able to focus well is because the Tasco eyepieces are indeed of very poor quality. My first scope was a Tasco. But the Tasco of 1973 is a gem compared to the Tasco of the 90's. At least mine uses almost no plastic. But even so, the eyepieces that came with my scope are very poor. When I was able to borrow my friend Pete's Unitron eyepieces, WOW! It was like having a whole new scope! Finally I got my own Unitron eyepiece in 1975, and it was the eyepiece I used almost exclusively.

Unless things have changed in a major way, the main objective of your scope is probably not bad (the one on my Tasco is actually quite good). This being the case, there is something you can do that will greatly improve the performance of your unit. You could spend as little as about $35 to make a big improvement, and if you can swing $100 or so, you'll be well on the way to some decent views.

I am willing to bet that the star diagonal that came with your unit is of very poor quality (as are the eyepieces). So, there are two items that need upgrading: the diagonal and the eyepiece. Here's what to do:

If you get the hybrid diagonal, you can step up to the higher quality 1 1/4" eyepieces. If you want to keep costs down, go with Orion's Explorer II series in the 1 1/4" size. The 25mm is cat # 8150, and the 10mm is #8152 (each sells for $34.95). If you can afford more, consider Orion's Sirius Plossl series. My recommendation would be for the 26mm (cat # 8732, $49.95) which will provide a magnification of about 35x. For the higher magnification, go with the 10mm (cat # 8736, $49.95). The Orion Sirius Plossl eyepieces are very good (not the absolute best, but very good) and would not be something you would soon outgrow even if you traded up to a scope with much higher performance capabilities. There are certainly better and much more expensive eyepieces you could also consider, but with the Tasco you have it would not make sense to invest in such units.

I have ordered from Orion on many occasions and found the products to be of very high quality. (ed. note: I receive no "kickback" whatsoever from Orion for recommending their products). I recommend them because I have used the products and believe that they are very good. Orion's catalog is very good also; there are many tips and loads of products. There are other companies that offer all kinds of accessories, but Orion seems to have the best selection of stuff for smaller scopes in my opinion.

You do not mention if the sky in your area is affected by Light Pollution. Can you see many, many stars and the Milky Way on a clear Moonless night? Or, is the sky in a permanent "twilight" due to a nearby city? If so, your viewing of the Moon and planets will not be affected, but objects such as star clusters, nebulae and galaxies will be compromised to some degree. If you have not learned the constellations, that would be the first thing to do to help find your way around the sky. Looking for deep sky objects without knowing the constellations is like trying to find someone's house in the city when none of the streets have signs! If you do not have one, consider picking up a star atlas. Starter atlases are not expensive ($15 or less), and may last you many, many years (I often still use one of my first star atlases from 1975 to this day). The Orion catalog has a number to chose from. A good choice would be "Sky Atlas for Small Telescopes and Binoculars" ($12.95) or even Orion's "DeepMap 600" ($13.95). I have a review of this item under the "Equipment Review" page of AAN.

So, I hope I have helped. Do strongly consider upgrading at least your eyepiece. That alone will be the single best improvement you could make to the Tasco scope.

Joe Roberts

TOPIC: Fixing up a Tasco telescope


I just purchased a telescope at a garage sale. On it is engraved Tasco 851 TR D=60mm, F=900mm, coated optics. I discovered there is no lens in the eyepiece. Is there a way that you know that I could purchase a lens and easily install it? Or should I just be thankful that I spent only $20 and that it was a charity garage sale? I have read your tips and appreciate your advice. I know not to expect great things from this machine but I think it would be fun to give it a try with my kids. Thanks a lot from a definite beginner.


The scope you bought is a Tasco 2.4" refractor, a very common starter scope. The older Tasco scopes (from the 1960's) were actually not too bad. It's the more recent models where the quality has gone down the tubes. The model you have is one of the "longer" focal length models (900mm is the focal length of the scope).

I am not sure if the telescope you have came with a star diagonal. This is an item that fits into the end of the tube where you look, and allows the user a more comfortable viewing position, especially when looking at things that are high up in the sky. You can do without a star diagonal, but most people really do find it much easier to have one.

You will need an eyepiece for this scope in order to look at anything. Fortunately, there is a company which offers decent quality eyepieces for telescopes like yours for reasonable prices. The company is Orion Telescope and Binoculars. You can get a catalog from them (for free) by calling (800) 447-1001.

The eyepiece I recommend is Orion's 25mm .965 Explorer II. It sells for $29.95 plus S+H. The catalog number of this item is #8130. This eyepiece will provide a magnification of 36 power in your telescope. This is a low magnification, but don't be fooled by the term "low". Low magnification IS what you want for this telescope. Later, if you find that the telescope may be used more often by you or your children, you can always get another eyepiece that will provide higher magnification views of the planets and the Moon. Such an eyepiece would be Orion's 10mm .965 Explorer II, also selling for $29.95 plus S+H (cat #8132).

If you want to get a star diagonal (I would recommend it if you have the extra $$), Orion also has one to fit your needs. It is catalog number #8761, selling for $29.95 plus S+H. Note that these items from Orion are much better quality than the ones that would have originally come with the Tasco unit.

So, your investment to get this scope "working" will be several times what you paid for the unit itself, but you will have a much better performing unit that if you spent $150 for a new Tasco. (This assumes that there is nothing else major missing or wrong with the unit). It is a small telescope, but it can show some objects quite nicely (especially the Moon). You can also use it to look at things in the daytime, but keep in mind that the images will appear "backwards" unless you purchase (yet) another accessory. Most people can get used to the reverse images. Whatever you do, do not look at the Sun with this unit!

By far the best target for this scope would be the Moon. Try to look at the Moon at around quarter phase for the most spectacular views (the full Moon shows less detail because there are no shadows).

Hope this helps. If you need more info by all means write back! Joe Roberts

TOPIC: Fixing up a tasco Telescope


Please help! We recently bought a Tasco telescope, model #302058 for our daughter. It's a refractor telescope, that came with three eyepieces, a 12.5mm, 4mm and a Barlow lens. We can't see anything in the night sky!!! What lenses are best for what viewing? The telescope came with horrible directions, we can't understand a word of it! If you have any suggestions, it would really be appreciated. Thank you.


I am not familiar with the particular model Tasco telescope that you have, but I can still respond to your questions. I am sorry to report that Tasco telescopes are at the "low end" in quality. For starters, do not even attempt to use the 4mm eyepiece or the barlow. The 4mm eyepiece will produce a power that is too high for a 2.4" scope to use, and the "eye relief" of the eyepiece will be extremely small (this basically means that it will be very difficult to physically look through). Tasco barlow lenses are of low quality, you are better off not using it at all. The only eyepiece that has a chance of producing a "reasonable" view is the 12.5 mm. This will produce a magnification of about 56x in your scope (I am assuming it is one of the 700mm focal length models). However, Tasco eyepieces have very narrow apparent fields, and even this eyepiece is likely to be marginal at best. I expect that the star diagonal that came with the scope is also of very marginal quality if it is anything like the ones I saw in a department store not too long ago.

For night viewing, the only eyepiece you should even attempt to use is the 12.5mm. It is possible that the finder scope is not lined up correctly; this might explain why you are having trouble finding anything. Unfortunately, Tasco telescopes use a "3 point" alignment method, which is very prone to being knocked out of alignment. Never hold or move the telescope by holding the finder scope (this will almost certainly knock it out of alignment). You will need to do an initial alignment; this can be done during the day (using an object way off in the distance) or by night using the Moon or a very bright star. You will have to first locate the object in the main scope, and then adjust the screws on the finder scope such that the object is centered on the crosshairs. Once you do this, recheck the position to make sure that any object you place in the crosshairs appears near the center of the view in the main scope.

To "fix up" this Tasco telescope, my recommendation is to upgrade a few items (assuming you are willing to invest more money). Orion telescope has good quality accessories for telescopes such as Tasco. My personal recommendation is to purchase their 25mm .965 eyepiece (cat no. 8130); this costs $29.95 plus S+H. If you wanted another eyepiece to get closer views of the Moon and planets, I would recommend Orion's 10mm .965 eyepiece (cat no. 8132), this is also $29.95 plus S+H. The 25mm eyepiece will give you a magnification of 28x, and the 10mm will give 70x. If you can swing a little more, I would also upgrade the star diagonal. Orion also carries an excellent selection. The model to get for your scope would be cat no. 8761 ($29.95 plus S+H). So, all of this will set you back around $100, but if you get just one item, get the 25mm eyepiece.

Orion has a web site at www.oriontel.com. They also have an number for a free catalog: (800) 447-1001. I have ordered from Orion an many occasions, and they are a very reputable outfit.

In the night sky, you want to use LOW POWER (12.5mm for the eyepiece you now have). It is much easier to find things using low power, and the views will be more crisp. You might want to read my article "Advise for First Time Telescope Buyers".

Hope this helps. Don't feel too bad about the Tasco unit. I started out with the very same brand some 25 years ago!

Joe Roberts

Astrophotography and Imaging Q+A

TOPIC: Beginner's Astrophotography


I was especially interested in the fact that you started out with a small Tasco refractor. I also have a Tasco 60 mm refractor and I have been learning how to use it. Did you start with photography using the Tasco? Were you able to attach a motor drive and a piggyback mount?

I would like to learn all I can using the Tasco before I start buying better equipment. I have added two Plossl eyepieces (medium and low power) and a good 2X Barlow. I have enjoyed moon and planet observation and am beginning to search for clusters and nebula.

I have been an amateur photographer ( I have a b & w darkroom ) for many years--owning already the non-automatic [old] cameras that are generally recommended. These include screw mount Pentaxes and Fujicas and an F2 Nikon with a waist level viewfinder. And a variety of pretty decent lenses (no zooms). With this old hobby in my background, I am very interested in photography applications in amateur astronomy.

If you have a chance sometime, drop me some advice for getting use out of the Tasco.


I did indeed start with a Tasco 2.4" refractor. However, the Tasco I started with is not the Tasco of the 1990's. Mine is a 1973 model, and compared to the ones they sell today, it is much better. There is almost no plastic on it; even the focuser is metal! The diagonal is a cast metal frame with a prism. The eyepieces that came with my scope were rather poor. I remember getting a Unitron 25mm eyepiece for my birthday in 1975 and WOW! What a difference a decent eyepiece makes! Pete Chapin (the other person who manages AAN) and I often observed together in the mid - late 70's, and this was very helpful to me because I was able to borrow his much better quality Unitron eyepieces.

My original Tasco scope was on an alt-azimuth mount, so motor drives were out of the question. I did obtain an equatorial mount for it in 1981, but in that year I also got a 6" equatorial reflector.

Much of my early piggyback shots were done using either Pete's Unitron refractor or a 6" Dynascope (reflector) that we borrowed from the high school. I did do some piggyback work with my original Tasco, but I quickly learned that even with "guiding" you still get circular star trails because of the alt -az mount.

It is very good that you have obtained some higher quality accessories for your scope. They really can make the difference. It is also wise to learn as much as you can on the "small" scope, because when you do trade up you will be that much better prepared to use the larger scope (and you'll appreciate it more).

Since you are familiar with photography, it will be much easier to get started. You *can* do some "afocal" lunar photography with the Tasco. Put in a low power eyepiece (one where the entire Moon fits comfortably within the field of view). On your SLR, use a "standard" or "mild" telephoto lens... say 50 to 100mm. Put the F stop open (no more than F2 though) to a fairly fast stop. Then hold the camera up to the eyepiece of the scope and focus using the telescope and/or camera lens. If you have a light meter, you can use it to *roughly* judge the length of the exposure. Be sure to "bracket" your exposures at least 2 stops either side of what the meter says. This afocal method really can result in some nice shots of the Moon. I have done this with various telescopes, including the Tasco 2.4". For an example of one such shot, look at my review of the Meade 4500 on the "Equipment Review" page of AAN.

Based on your message, I think you read my article "Astrophotography for Beginners" (if not it might provide some other ideas). Be sure to try some fixed tripod shots of star fields. If you have a motor drive on your scope, you can do some piggyback astrophotography (a polar aligned equatorial mount is a must however). You *can* guide by hand using a slow motion control, but it requires a very steady hand! If you try this, use the very highest power eyepiece you have to guide on a reasonably bright star. And, don't use camera lenses above about 50mm with this manual method (guiding aberrations will show up on the film).

Based on your location, I'm guessing you face rather severe amount of light pollution when you observe and photograph. This will not hinder observing or photographing the Moon, but it will severely limit your ability to look at deep sky objects. If at all possible, try to get to a darker area. I have seen all of the Messier objects (and several hundred other NGC objects) using a Tasco 2.4" scope, but this was done back in the 70's under some pretty decent skies. Trying to repeat this today with the same equipment in the same local would be a real challenge due to the spread of light pollution. When you go from a bad sky to a nice dark sky, it's like doubling the size of your scope! It really has a dramatic affect on what you are able to see (and how well you are able to see).

Since you are familiar with B+W, I'd say try some TMAX 400 (Kodak) film for astrophotography. I have also used Tri-X (but not recently) with decent results on both the Moon and star fields.

TOPIC: Astrophotography with the Meade 4500 Newtonian Telescope


I am about to buy a small portable telescope. I thought the Meade 4500 might be a nice choice but after I've read your really GREAT page I'm little disappointed about what you have written on Meade 4500 and prime focus astrophotography. Which type of camera adapter did you try? Was it Meade basic camera adapter? And how does such a camera adapter work? I think the focus plane of most Newtonian telescopes lies too close to the tube, so it is impossible to bring a camera to a proper position. Do camera adapters contain some optics?


First, thank you very much for the compliment on the web page. The camera adapter I used was an Orion (brand name), however it is virtually identical to the Meade 1 1/4" "Variable Projection Camera Adapter". I used the camera adapter in its shortest possible configuration and could still not bring the camera to focus (I did this by unscrewing the 1 1/4 inch adapter part and threading the camera T-ring onto this part, eliminating the extra length that would otherwise result from using the entire adapter). This particular camera adapter has no optical elements (ones that do can be identified by their price; often triple or quadruple the cost of a standard adapter).

The camera adapter is little more than a mechanical assembly that allows an SLR camera to be placed into the telescope drawtube (as if the camera was an eyepiece). Most of them are very similar. Some do have optical elements in order to allow a camera to be brought to focus (the Edmund Astroscan camera adapter is one such example).

If you are willing to do some modifications, you *could* modify the Meade 4500 to make it focus without a special optical camera adapter. Basically you will have to move the mirror towards the focuser a slight amount. However, if you are just starting out I personally would not recommend this option (if for no other reason it will void the Meade warranty). As I mention in the review of the Meade 4500, it is not really a telescope intended for astrophotography. You can do "afocal" astrophotography with it (I hope to soon write an article covering this in my "Astrophotography for Beginners" page). The Meade 4500 is a nice starter telescope, and it has enough capabilities to get your "feet wet" in astrophotography. If your plan is to pursue astrophotography in a fairly serious manner, the Meade 4500 is not really the best choice. Telescopes that can do serious astrophotography generally cost $1000 (US) and higher.

Hope this helps! Joe Roberts

TOPIC: Beginner's Astrophotography


I have been an avid amateur astronomer for many years. I am looking into buying photographic equipment to start some astrophotography, but I don't know where to begin. Can you help me? I was wondering what is the best type or brand of camera, what features to look or ask for, what is the best film, etc. Also, if you know of any links that could help, could you forward them along as well?


There are many ways to get into astrophotography, and to be successful you must start simple and work your way into more advanced topics. "Jumping in" with tons of expensive equipment and trying advance topics without "learning the ropes" will very likely lead to frustration and poor results.

There are a number of features that are important in a camera to be used for astrophotography. You should try to find a 35mm SLR camera that DOES NOT require a battery for it to operate. You will need one capable of doing time exposures, and one that can accept a remote shutter release cable. It does not matter of the light meter works (you won't use it for night photography). The shutter should be in good working order. Be sure and get a 35mm camera with interchangeable lenses. An SLR is the best choice, as it allows focusing directly through the viewfinder. I use two cameras... a Pentax K1000 and an old Cannon FT. There is no need to buy a $1000 feature laden camera (in fact, you are better off NOT using a very expensive camera, as it will be subjected to extreme cold, moisture, etc.). Again, the cameras I use are "good" cameras, but not "top of the line". For astrophotography, the camera is really just a film holder. The quality of the photos you take will be much more dependent on the quality of the lens, NOT the camera!

For lenses, fixed lenses (as compared to "zoom" lenses) are generally better (unless they are of top quality). Good ones to start with are a 50mm and a 28mm. Both of these will allow you to get decent photographs of constellations. Higher power lenses (like 135mm, 200mm, etc.) require a steady mount that can track the stars. If you have a very fast lens, it's best not to set the F-stop to faster than F2 (F2.8 to F4 is where most lenses give the best image for astrophotography). You'll also need a tripod, as the first pictures you'll do are short (30 second to 1 or 2 minute) time exposures of constellations.

As for film, I have only used popular consumer films (I am not a professional and have not tried any of the professional harder to find films). I have done mostly print film so I cannot comment too much on slide films. I have had very good results with Kodak Royal Gold 400 and 1000. Also, Fuji Super G 800 is good. For black and white, Kodak TMAX 400 is a good choice. It's best if you can process and print your film yourself if at all possible. "One hour" photo shops usually do a pretty decent job with the color work (none of them do black and white on site however). It's best not to send color print films to "mail away" processing, as the negatives sometimes come back cut in the wrong place. When (if) you take your film to a one hour place, tell them NOT to cut the negatives!!! Do it yourself and you will save yourself possible tremendous disappointment.

There are many links on the web on taking astrophotos. If you type "astrophotography" into most any search engine (Yahoo, Excite, Lycos, etc.) you'll likely come up with numerous places to look. Sky and Telescope magazine has had numerous articles for beginning astrophotographers. Their web address is www.skypub.com.

I've only touched on the very surface of getting started in astrophotography. Remember.... start simple and you'll have little or no trouble getting decent results. Then, work your way into more advance techniques as your skills and experience grows. Astrophotography is a challenging form of photography and takes years to master. I've been doing astrophotography on and off for 20 something years, and I still consider myself an "intermediate" astrophotographer!

Hope this helps, Joe Roberts

TOPIC: Astrophotography with a Dobsonian telescope


I am 15 years old and I'm just getting started out in the field of astronomy. I recently got (with the help of my parents) a new Orion DSE Dobsonian 8" reflecting scope with the 6x30 finder. Tonight was just my second night using the scope and I was able to M42, M43, and Saturn. I'm interested in astrophotography and have no clue what kind of cameras, film, eyepiece adapters I need and I was wondering if you could give me some pointers on what I should get when I decide to purchase the new equipment. Any advice you could give me would be greatly appreciated. Thanks for your time!


You are off to a good start with the Orion scope. When I was your age I had a 2.4 inch scope... an 8" scope would blow that "out of the water"!

Anyway, on to your question about photography.... First, a Dobsonian scope is relatively limited for astrophotography because of the mounting (which by design is intended primarily for visual use). You could however use the 8" DSE for taking shots of the Moon.

The best way to start out with astrophotography is to take photos of the constellations (or star fields). To do this, you'll need a camera, tripod, and the correct film. As for the camera, you'll need a 35mm SLR (the kind where you can remove and change lenses). Make sure the camera has a "B" (time exposure) setting on the shutter speed control and make sure it can accept a remote shutter cable release. Also, try to be sure that the camera you use DOES NOT REQUIRE THE BATTERY for the "B" setting to work. If it does require the battery, plan on spending a fortune on batteries! As information, the cameras I use most for astrophotography are a Pentax K1000 and an old Cannon FT (1970's vintage). The Pentax K1000 is still available today (cost is around $160 without the lens). This is a very basic camera, but it is a GOOD camera. If you are buying a camera specifically for use in astrophotography, DO NOT buy a $500 "bells and whistles" camera... those extra features will do absolutely nothing for astrophotos (and may even hinder your ability to work with the camera!).

As for lenses, a 50mm F4 (or faster) lens is a good starter lens. Wide angle (28mm) lenses are also useful, but they will exhibit some distortion. You can find 50mm lenses as fast as F1.2, but the distortion that results from super fast lenses is very noticeable on star pictures (unless you spend $1000 or so on the lens, not worth it in my opinion). I use an F2 lens and often stop it down to F4 (all lenses give comparably better images when not working "at their limits".

As for film, I am only familiar with popular print films (I can't speak for slides). I find that Kodak Royal Gold 400 and/or 1000 are very good. Note "Royal Gold", not just "Gold"! The regular Gold is not bad, but the extra $1 per roll (give or take) for Royal Gold is worth the money. Many people also like Fuji Super G800. For B+W, try Kodak TMAX 400.

For basic constellation shots, put the camera on the tripod, set the focus at infinity, set the lens to about F2 (can be anywhere between F1.8 and 4.0), point the camera at an interesting area of the sky, and expose the film for about 30 seconds. This length of exposure will keep star trailing to a minimum, and yet should record stars fainter than you can see (IF you live in a fairly dark sky area). When you get the film processed, tell the processor to NOT CUT the negatives! They often do not know how to handle astrophotos and they might ruin your otherwise good shots. Make sure they print EVERY frame also. I often go to the "1 hour" type places so I can give them specific instructions.

Taking pictures through your scope will be limited to the Moon (or the Sun IF YOU USE THE PROPER FILTER!!!!!!!!). You could get a 1 1/4 inch camera adapter from any one of a number of vendors (about $35 or so), OR you could try the "afocal" method. The afocal method means simply holding your camera (with a 50mm lens attached) up to the eyepiece of the scope and snapping pictures! It may be a bit tricky to get the Moon framed up at first. Use a LOW POWER eyepiece in the scope. Try 400 speed film, and take exposures at 1/30, 1/60, 1/125, 1/250, and 1/500 second (if the Moon is full go even higher). Astrophotography is a "hit and miss" type of activity when you are starting out... don't expect every shot to be good. In fact, expect only a few really good shots PER ROLL of film shot! It takes a lot of practice and some luck to get consistently good results.

Recommendation: don't try photographing the Sun until you become more experienced and have the proper equipment. One mistake could mean permanent blindness and /or a ruined camera.

If you don't have a camera that is now suitable for astrophotography (those "point and shoot auto everything" cameras will NOT work for this kind of work!), plan on allocating at least $250 - $300 for starter equipment: (prices approximate depending on the quality of the stuff you buy)

I hope this helps. Don't expect to get magazine quality shots at first. Astrophotography takes patience, practice and luck. I've been at it on and off since 1975 and I still consider myself at the "intermediate" level!

Best of luck... Joe Roberts

TOPIC: Video Cameras and telescope imaging


I was wondering if it possible to record images through a telescope with a video camera. How would I do it?


Yes, it is possible to record images through the telescope with a video camera, but there are a few things to know. I have recorded video through my Meade 4500 telescope using a 1989 vintage full size Panasonic VHS camcorder (I think it's an 8 lux unit). I found that taking video of the Moon worked rather well. No other objects were bright enough to record a useful image. The planets are bright enough at low magnification, but the problem is that they are too small to show more than a dot on the video. The biggest pain was holding the camera up to the eyepiece of the telescope and keeping it centered on the object and moving the telescope such that it followed the object being filmed! My Meade 4500 has no clock drive so I had to do this manually. I used a tripod to position the camera as close to the eyepiece of the telescope as possible. Suggestion: Use a "skylight" filter on your video camera; this will prevent damage to the actual video camera lens should you bump the eyepiece (which if you are like me you will undoubtedly do). Also: I found that the images were by far the best when the zoom lens of the camera was zoomed to the maximum magnification. I put the camera focus on manual and used the telescope focuser to achieve focus. I used a low power eyepiece (36x) in the telescope. I did all of this while looking through the viewfinder of the camera.

It may be possible to make a special mount that holds the camera up to the eyepiece of the telescope, but the weight of the camera (at least the weight of my camera anyway!) will likely be a severe strain on a mount like that which comes with the Meade 4500.

Video imaging of the Moon offers some very cool opportunities to get some great images. When a video camera records images, it "takes a picture" every 1/30 of a second; some can be set for "high speed shutter" which takes the image in a much shorter time (these settings typically require a lot of light). The video is little more than a series of "stills" of a subject. By taking video of the Moon, it is possible to walk through the images (using a 4 head VCR that produces a noiseless paused image) and pick out those that happened to be taken at a time of good seeing. If you have a video capture device like Snappy, you can then capture the "good" image of the Moon and convert it to a computer image (JPEG is usually used).

When I tried doing video through the telescope, I was basically just "fooling around" to see what would happen. To my surprise, it worked quite well! And, my video camera is old by today's standards; newer cameras have considerably improved images. I want to try video of the Moon using my 11" scope sometime. The extra image brightness will allow me to increase the magnification considerably.

Don't hesitate to try video through your telescope. Use the tips I have provided as starting points. You will soon find what works best for you, and the results will probably be pretty nice!

Hope this helps, Joe Roberts

TOPIC: Astrophotography using the Meade 4500 scope


I am a person just getting into astronomy. I saw your pictures and I think you did a great job. I have the Meade 4500 telescope. I was wondering if you could tell me everything I need to take pictures of nebulae etc. Thank you for you time.


The Meade 4500 is an excellent starter scope, but for taking pictures its capabilities will be limited (unless you are willing to invest considerable $$ for extra necessary equipment).

For taking time exposures of deep sky objects, you need a very stable mount with slow motion controls in both axes. The Meade mount could be modified to do this, but it will still be rather difficult to get pictures that do not show "shaky" stars. For one thing, the Meade 4500 does not have an easy way to do polar alignment (required for taking deep sky pictures).

The Meade 4500 SHOULD be good for taking shots of the Moon, BUT, I tried it and I found that the camera cannot be brought to focus! To make it come to focus, the main mirror would have to be moved (not an impossible modification, but not one for a beginner). I did take some Moon pictures though the Meade 4500 using the "afocal" method; basically I held my 35mm camera (with its own lens in place) up to the eyepiece of the scope. The pictures came out pretty decent, but this method will only work for the Moon.

The Meade 4500 is capable of being a "piggyback platform" for constellation shots if you obtain a motor drive. Basically, the Meade will act as the tracking platform for the camera (which can have anything from a wide angle to moderate telephoto lens). The tracking error of the Meade should be sufficient to do exposures up to many minutes with a 50mm lens (assuming you do a decent polar alignment).

If you are serious about getting deep sky shots of galaxies, clusters, and nebulae, you will really need a more advance telescope and mount. Many astrophotographers use the Losmandy mounts (the Losmandy G-11 is supplied with the Celestron CG-11 scope, which is what I use). They also make a smaller version for scopes in the 5" to 8" range. The important features for a mount to be used for astrophotography:

There are a number of mounts available to meet these requirements. Celestron and Meade scopes are a few of the more popular scopes with mounts suitable for astrophotography. Good mounts (and scopes) for astrophotography are not inexpensive; expect to pay about $2000 and up for a decent setup.

That's the basics. My personal recommendation is to learn the sky using the scope you now have. Start out with basic astrophotography (tripod mounted camera taking constellation pictures), and then work your way up to more advance topics if your interest holds. Astrophotography is a challenging form of photography, and takes YEARS to master. I've been at it off and on for 23+ years and still have a long way to go!

Hope this helps.... Joe Roberts

Planetary Alignment and Conjunction Q+A

TOPIC: Venus - Jupiter conjucntions 1700 AD - 2200 AD


I heard that the Venus - Jupiter conjunction of 23 February was one of the closest ever. Is this true? When will they be close again?


I ran some conjunction searches for Venus and Jupiter using Redshift 2, and the results did surprise me...

It turns out that close Venus-Jupiter conjunctions are quite common. I told the program to search for pairings of 0.5 degrees or closer from 1700AD to 2200 AD. It found 190 of them! That means that conjunctions of .5 degrees (pretty close by my terms) occur on average every 2.63 years.

I then tightened up the separation to 0.166 degrees (1/6th of a degree); this is a little less than the distance between Mizar and Alcor (in the bend of the handle of the Big Dipper). Over the same time period there were 50 conjunctions that met this criteria. This means that conjunctions that are quite close occur on average about once every ten years.

Some other interesting items...

The conjunction we saw on 23 February was certainly close, but not as close as some in recent years. On August 12 1990 the pair was only 0.041 degrees apart, compared to the 0.134 degrees of the 23 Feb 1999 conjunction!

On January 3, 1818, Venus partially occulted Jupiter... I guess this would be considered a "very close pair". The same thing will happen on Sep 14, 2123.

Interestingly, if Jupiter and Venus were to approach to within closer than about 3 arc minutes (0.05 degrees), the human eye would start to have difficulty seeing them as two separate objects. However, the "melding" of these two would not make Venus appear significantly brighter!

On May 17, 2000, Jupiter and Venus will be only 0.048 degrees apart. Unfortunately, this will occur too close to the Sun for any kind of a view. I suspect many of these conjunctions do occur very close to the Sun (all of them by definition occur fairly close to the Sun because Venus cannot stray more than about 45 degrees from the Sun as seen from Earth).

The next conjunction that we can see that will be closer than the one we just saw occurs on August 27, 2016. Jupiter and Venus will then be only 0.066 degrees apart, about half of what they were yesterday. This event will be best seen from the southern hemisphere (as it occurs in Virgo with the Sun in Leo). From the north, a good, unobstructed southwest horizon will be required in order to see it. This one will be the closest one that most of us can expect to see in the rest of our expected lifetimes...

TOPIC: Planetary Alignments in the future


I heard of an upcoming event somewhere in the near future when all the planets in the solar system align in one straight line. Could you tell me, if a thing like that really expected and when is it due?


Hello! Thanks for your note. It happens that someone asked us essentially that same question a few months back. In response Joe made use of the Redshift II program he has to compute some conjunctions for the major planets. He found that such events are quite rare. (Keep in mind that a "perfect" alignment is just about impossible since the planets have slightly different orbital inclinations). Here is the message Joe sent me regarding that earlier request. Perhaps you would also find it interesting.

I worked that planetary alignment question that was submitted. As it turns out, there are no really close alignments of all planets he requested (Earth, Jupiter, Saturn, Uranus and Neptune). The primary reason (as I'm sure you can guess)... the orbital periods of the outer planets are long. Being that we just went through a Uranus-Neptune conjunction a few years back, another one will not come around for a long time. Anyway, the searches I was able to come up with are as follows:

You may notice that the alignments come at 20 year intervals. This is primarily due to Jupiter and Saturn. They "group" up every 20 years or so. Every once in a while this dominating pair happens to be fairly close to one of the outer planets. Having *all* of them close together (say within 10 degrees) is a rather rare occurrence (in terms of human lifetime).

I did some more checking on that planetary alignment question (mostly out of curiosity). Turns out that the conjunction the reader asked about is quite rare in terms of the "modern history" time line. Redshift 2 searches for conjunctions based on a number of user entries; the widest spacing it considers a "conjunction" is 9.99 degrees. The program can do searches from 4700 BC to 11000 AD. In this time span, there are only 4 such conjunctions of 10 degrees or less! They are summarized below:

That's the list! No one alive today has ever seen an event similar to the one that the reader asked about.

TOPIC: Finding information on planet visibility




There are a number of resources for finding this information, but most of them will list the info only for this calendar year. If you have a copy of "The Old Farmer's Almanac" around the house (or one of the similar almanacs), they list all of the info for planet visibility (but again, only out to the end of the year).

You might be able to get some of the info from Sky and Telescope's web site. It is at: http://www.skypub.com

Another way would be to use some astronomical software to determine the visibility of the planets. The problem here of course is gaining access to such software if you don't have it. Local libraries might possibly have some.

If you have no other alternative, I can use some of my software to give you general info on the visibility of the planets. If you do take me up on this offer, I'll give you the basic information for the planet visibility, but it will be your job to arrange the info into a table! Also please note that due to the demands on my time it might take me a few days to prepare the info.

Good luck with the Merit Badge! Joe Roberts

Telescope and Equipment Q+A

TOPIC: Celestron Celestar 8" or Orion 6" F5 telescope?


I am a victim of a "department store" Tasco telescope, but I did learn a lot even with this unit. I'm now looking at a couple of scopes that have caught my interest. I would like your opinion. The first telescope is the Celestron Celestar 8" F10 SCT and the second telescope if the new Orion 6" F5 equatorial Newtonian reflector (with motor drive). My question is: Is the $300 difference worth the move up to the Celestron with 2 additional inches of mirror? Is there really a big difference in performance between the two?


The difference in image brightness between a 6" scope and an 8" scope is certainly noticeable but not overwhelming. Stars will appear about .5 magnitudes brighter in the 8" scope as compared to the 6". This "extra" power will be most noticeable on objects near the limit of visibility, like stars in globular clusters and faint detail in emission nebulae.

The 6" F5 scope would be better suited for low power wide field viewing. It would also be much faster (by a factor of 4) for astrophotography. Optical systems of F5 are considered "fast" (as far as telescopes are concerned anyway); the downside is that fast optical systems require precise collimation for optimum views (slower systems are more forgiving of misalignment). Also, fast optical systems tax the performance of eyepieces; fast telescopes tend to exhibit a phenomenon called "coma"; the result is that stars towards the edge of the field of view will not focus to fine points. (You can get a device called a "coma corrector" to minimize this effect). In general you will need eyepieces of comparatively high quality when they are to be used in a "fast" scope if image quality is to be at its best.

The 8" F10 system is a "moderate to slow" system optically. An 8" F10 SCT is a good "all around" performer. It will provide good views of all types of astronomical objects (however the 6" F5 system would win in the "rich field" category). Another advantage of SCTs is the tremendous array of accessories available for them.

Which scope would I opt for? If forced to make a choice I would lean towards the 8" SCT. Not that the 6" unit is lacking (it is a good unit), it's just that I feel the 8" SCT is a better "all around" scope (and it does have the extra 2" of mirror). It does however come at a significantly higher cost. In any event, either scope would be vastly superior to any Tasco unit!

Hope this helps, and thanks for visiting out site. Joe Roberts

TOPIC: Celestar 8 as a first scope


What do you think about a Celestron Celestar 8 as a 'first telescope'? I have interest in planets, deep sky objects, and the moon. I also may have interest in astrophotography but I am not sure yet. My budget is $1500.


Before going into any specifics of the Celestar 8, let me say that 8" SCTs are one of the most popular telescopes available today. The reasons are many, but perhaps the most dominating is that an 8" SCT offers some very nice viewing combined with decent portability. An 8" F10 SCT is a good "all around" telescope. It will work well on all the objects you mention. You may have read that SCTs are not ideal for planets. This is technically true, but SCTs can offer some very nice planetary viewing nonetheless (especially when color filters are used). Another nice thing about SCTs: there is an abundance of accessories available and many will work on other telescopes as well.

As for the Celestar 8, I do not own one and have not used one personally. I do believe that all Celestron 8" scopes use the same optics, so the main difference in performance will be in the mounting. There are several models of the Celestar 8, but with a $1500 budget you will be limited to the basic model (which is still a very capable unit).

One thing about the Celestar 8 that Celestron seems to tout is that it can operate on only a 9v battery. While this is not a false statement, it is misleading. One thing you will require for an SCT is a dew cap and/or a "dew heater". A standard dew cap will give you an hour or two of observing on damp nights, but if you plan to be out for longer than this, a "dew heater" will be a necessity. No dew heater will operate on a 9v battery; you will need something more like a motorcycle battery. You can start with a dew cap, but you may find that you need to move up to a dew heater as well (I use both; the dew cap helps to keep stray light and dust from hitting the front optics). In addition, the Celestar 8 comes with only one eyepiece; I'd recommend getting at least one other to provide a nice, low power field (something like a decent 35 to 40mm eyepiece).

Because of the low price of the Celestar 8, it comes with no storage or transportation cases. You may want to budget some money for such items if you plan to transport the scope any great distance. It will certainly survive the trip in the back of a car without cases, but scratches and other cosmetic damage will eventually result.

In summary the Celestar 8 will open up a tremendous amount of viewing possibilities for you. It can be upgraded to do some fairly sophisticated astrophotography should you decide to pursue this in the future.

Hope this helps, and thanks for visiting our site! Joe Roberts

TOPIC: Newtonian optical system collimation


I've gotten hold of all the information I could, got a subscription to Astronomy and plunged in. I have an 8" Meade Dobsonian (with the accessory kit) and I can't stop looking at the moon. The collimating instructions that came with the scope are poor. Any suggestions?


The 8" Meade Dob is a decent scope from what I've read (never have actually looked through one). I agree that the collimation instructions that typically come with telescopes are not often too clear. I one day hope to write an article on how to do the task. Describing how to do it is greatly enhanced with the use of diagrams.

I am not sure what (if any) adjustments are possible on the secondary mirror of the Meade 8" Dob. Does it have a single "stalk" secondary mount or is it a 4 vane spider? If it is a 4 vane spider, can you see any adjustment screws (there will probably be three)? I have no experience collimating scopes with a single stalk for the secondary.

The primary mirror in your scope sits in a cell which will be adjustable by three screws (or similar) at the rear of the optical tube.

Collimation basically involves making the optical system "true" (sort of like aligning the tires on a car). If the alignment is off, a telescope will still perform, but the performance may be unsatisfactory (as would the performance of a car if the tires are all messed up).

The secondary mirror adjustments are the more difficult in my opinion. When you look through the drawtube (with the no eyepiece in place, in daylight, and with your eye about 1 foot back from the drawtube), you should verify that the secondary mirror appears centered in the drawtube hole (if not, you will have to adjust its position using provisions on the spider).

Next, you will have to make sure that the image of the *primary* mirror is centered in the secondary (your eye may have to be quite a bit closer to the optical tube for this step). If it is not, you will have to adjust the secondary's position using the three (typically) screws at the front of the secondary mount. The final adjustment is done to the primary mirror. You now have to verify that the image of the *secondary* mirror is centered within the image of the primary mirror while looking into the drawtube (confusing in words, not bad in diagrams!). To accomplish this task, adjustments are made to the set screws on the primary mirror's cell. You may need a helper to make this go easier. While you look through the drawtube, have someone slowly adjust the position of one of the set screws at the primary cell and note which way the secondary image moves. You may have to adjust more than one screw to center up the image. All in all, you may have to do some "trial and error" tinkering. Often, turning the screw that you think will help actually moves things to a worse position!

I know my explanation is not too great. Diagrams really would be a major help! Also, keep in mind that final touch ups may need to be done outside at night using a fairly bright star. Ideally, the star image should look the same on both sides of focus, and the image of the secondary (and the vanes) should be centered in the out of focus star when the star is centered in the field of view. Bad seeing conditions can make final touchups a real pain. When the scope is perfectly collimated, star images should be symmetrical and round, with spikes (if any) being equal in length and brightness (bad optics can also yield crappy performance that collimation will not help). Make sure you wait until the scope has reached thermal equilibrium before doing any critical star tests!

I hope this helps a little bit. I'll make it a higher priority to write a detailed article on collimation... Best of luck, Joe Roberts

NOTE: A reader of AAN e-mailed in and noted that Meade has "on line" instructions for collimating the Meade 4500 scope. The same basic procedures apply to most Newtonian reflecting telescopes. The instructions are located at: http://www.meade.com/m4500.html

ALSO:Orion Telescope and Binoculars sells a special collimating eyepiece (cat #3640) for $34.95 plus S+H. I have never tried one of these accessories, but it may be worth checking out!

TOPIC: 4.5" Newtonian Reflector telescopes


I am looking at buying a 4.5" reflector and have narrowed down my choices to the Celestron and Meade telescopes due to availability in this country. I have read your review on the Meade 4500 and would like to know if you know anything about the Celestron or other similar telescopes.


I do have direct experience with the Meade 4500 scope (as you know from the review article). I do have direct experience with Celestron products, but not the 4.5 inch reflectors.

Celestron has a number of 4.5 " reflectors, but the best one (by a considerable margin) is Model C114-HD. This scope is superior in that it has a much better mounting than the other 4.5" scopes they offer (do note that the price is accordingly higher as would be expected). The C114-HD mount can accept a polar alignment finderscope, and the mount appears much more suited to astrophotography (if you were planning to eventually get into this). I would say (based on the description and photos in the ads) that the mount on the C114-HD is considerably better than the one on the Meade 4500 that I own.

The size and type of telescope you consider for purchase really depends on what activities you plan to get into. If you are planning primarily visual observations, you might consider a Dobsonian reflector. This type of scope will allow you to get the best views for a given amount money. Dobsonians are not suited to more advanced activities such as astrophotography however. You could get a 6" Dobsonian reflector for about the same cost as one of the equatorially mounted 4.5" reflectors; a 6" scope will provide a view that is considerably brighter than that of a 4.5" scope.

I do not happen to have a Celestron catalog with me at the moment so I can't look up the prices and features of the various Celestron models. However, you may be able to find such info on Celestron's web site (I believe it is at www.celestron.com). Meade also has a site (www.meade.com I believe). Meade has a complete on line catalog.

I can say that the Meade 4500 is a decent unit for the cost. It does have a few areas that could be improved (as I mention in my review), but most any scope has some peculiarities. Based on my experience with Celestron scopes, I suspect that their 4.5" scopes are also decent (especially the C114-HD).

Hope this helps... if you have other questions feel free to write again! Joe Roberts

TOPIC: Edmund Astroscan and Barlow Lens use


I own an Astroscan, with the standard 28mm eyepiece and an 8mm one (also Edmund's). I'd like to get a Barlow to cover the gap, as well as to push to higher magnifications without getting extremely low eye-relief (the 8mm is bad enough!) or very high prices. I had a Barlow back in the 60's, but I don't have fond memories of it! I understand that today's Barlows are much better. I am considering the Celestron Ultima 2x, the equivalent Meade 2x, and the Meade 2x-3x. I'm guessing that you might have some experience in this area, so if you could offer any advice (or point me elsewhere), I'd appreciate it. Is the Ultima "too good" for the Astroscan? Is the 2x-3x good enough? Does the Astroscan have focus-travel problems with a Barlow?


It is true that modern barlows (of the brands you mention) are far and away better than the "stock" barlows that used to come with almost every entry level scope. I have not used the Ultima or Meade barlows, so I cannot directly vouch for their performance (but I'd bet they are pretty good). I do have an Orion brand barlow and it is of very good quality, far better than the one I had previously (a Tasco unit).

As for use of a barlow in the Astroscan, I can speak to that somewhat. I own an Astroscan myself, and have found that in general the unit is not particularly well suited to the higher magnifications that a barlow will produce. The reasons for this are as follows: (1) the Astroscan is a very fast optical system (F4 or so). As such, aberrations will show easier at higher powers as compared to a slower scope. (2) Collimation: The Astroscan optical system is "fixed" meaning the user has no adjustments for collimating the unit. High magnification in a very fast scope requires that the collimation be very precise if the image is to be any good. In my experience, I find that powers above about 35x or so start to show signs of image degradation in the Astroscan (the stars do not focus to fine points). I believe that this is because the unit is not perfectly collimated (and being that there are no adjustments, it more or less cannot be changed). The Edmund factory can do a recollimation (for around $40), but I question how well the unit will stay in collimation during the trip back. The bottom line: the Astroscan really is not intended for high magnification viewing (despite what Edmund might claim is possible). It really excels at what it is primarily intended for... low power wide field views. It *can* be used for higher power viewing, but the image quality is noticeably inferior to those provided by similar size slower scopes (for example, I have a 4.5" Meade F8 Newtonian which is much better for observing at powers around 100x).

I don't want to discourage you from obtaining a barlow; just keep in mind that the views at the higher powers may not be so crisp. If you go with a 2x barlow, your 8mm eyepiece effectively becomes 4mm, producing about 111x in the Astroscan. I know in my Astroscan this power would produce images that were rather poor compared to the Meade 4500. Perhaps my Astroscan is especially out of collimation; yours may be better in this regard. Mine is a 1984 model.

I don't think that a barlow can be "too good" for any scope. Ideally, the barlow would double the magnification and only that. In reality, all barlows will introduce some light loss (good ones should pass 97% or better however), and all barlows introduce some loss of contrast (but this too should be very minimal, and probably not noticeable to the human eye). I cannot say whether or not the Astroscan has focus travel problems with a barlow... I never tried it.

I'm not sure if I have helped or not. Perhaps one of the astronomy newsgroups might offer more information. Joe Roberts

TOPIC: Celestron Firstscope 76 as a first telescope


I bought a telescope for me and my kid to look at the moon, planets and stars for fun. I purchased the Celestron Firstscope 76 for around $160. Seemed well made and I believe in getting quality over quantity. I was not sure, and still am not sure, if I should have got the Reflector or Refractor for general interest and observation.

My questions to you are: (1) for the general user wanting to let his kid observe the sky, is the Firstscope a good scope to see the moon, mars, Saturn,... ?? (2) Would a 60mm scope be better?? Thank you for your time.


I think the Firstscope 76 is decent starter choice for looking around the sky. It will show objects noticeably brighter than those in a 60mm scope. On the downside, the Firstscope 76 is a Newtonian reflector, and if not collimated it will show less than ideal images (this is where the refractor would win... no maintenance). The scope you have will show decent images of the major planets, although Mars will be nothing more than a small dot unless it is very close to the Earth, something that only comes along every few years (and when it does it's not for a very long time). The Moon should be spectacular through the Firstscope 76.

Looking over the "specs" on the Firstscope 76, it seems to be a decent starter unit. The price you paid was about right. This scope is undoubtedly made in Japan (or another far east country); the mounting is not as stable as higher priced models (no surprise however), but at least it's an equatorial mounting (which if aligned even roughly with the north pole will allow much easier tracking of objects). A 60mm refractor might have been a better choice if you were also going to do a lot of terrestrial observing (reflectors can be used for such observations, but are not ideally suited for this type of observation).

One word of caution: never let anyone look at the Sun with this (or any other) telescope unless you have the proper filter!

I'd say you made a decent choice of telescope for introducing your children to the night sky. And, if for whatever reason they loose interest in it, you have not invested a huge amount of money.

Hope this helps... Joe Roberts

TOPIC: Orion ShortTube 80 telescope for daytime photography and night viewing


I am interested in starting astronomy as a hobby, but would also like a scope for taking wildlife photographs. I have been looking at the Orion ShortTube 80mm Rich-Field Refractor and was wondering whether it was a good choice for both beginning astronomy and a daytime spotting scope. Thank you for your help.


The Orion ShortTube scope is a very good choice for what you plan to do. It's a rather compact scope which is important for easy transport, but being 80mm in diameter, it has decent light gathering power which is required for night viewing.

As for photography, the ShortTube 80mm will serve as a decent 400mm F5 telephoto lens. This would be a good lens for both daytime and nighttime shots. Keep in mind though that the lens is "fixed" at F5; to change exposure you have to change the shutter speed. For handheld work, this will mean shooting at shutter speeds no lower than 1/250 of a second if you have a very steady hand! Longer exposures will require a tripod or monopod. For nighttime work, you will need a tripod or equatorial mount.

Keep in mind that the Orion ShortTube does not come with a tripod or mount. For casual observing, a sturdy photographic tripod would probably suffice. If you plan to take astrophotos, you will need a good equatorial mount (except for the Moon). Also, for night observing, you may want to eventually consider getting a 90 degree diagonal (the ShortTube comes with a 45 degree diagonal). The reason is this: if you observe high overhead with a standard tripod, you'll end up with some very uncomfortable observing positions.

The ShortTube comes with two decent quality eyepieces. However, if you want a really impressive view, consider one of Televue's Naglers or Panoptics. These are expensive eyepieces (as much as or more than the cost of the scope itself), but they will provide breathtaking views. These eyepieces would be good for "later on" when you are sure you are "into" the hobby.

I do not personally own the Orion ShortTube (although I would not mind having one)! From what I've seen in the ads and from what I've heard, it's a decent scope for the money. Plus Orion has a money back guarantee so you can't loose too much (maybe a shipping cost or two). I have ordered from Orion on many occasions and I recommend them highly.

Hope this helps, Joe Roberts

TOPIC: Celestron Celestar 8 vs. Meade 8" LX-10


I read your article on buying a telescope. I have read several other by different authors. I got a Tasco telescope for Christmas and used it a couple of times and sent it back. I decided to get serious and by a telescope I could do something with. I have been researching for several months and have decided upon either a Celestar 8 or a Meade LX-10. What is your preference? I am interested in astrophotography. Do you have any info or opinions on either of these models? Is the basic Celestar (with DEC motor and hand control) adequate for astrophotography? I also wonder about the fixed length tripod. Is there a problem with polar alignment with a fixed length tripod if you are not on a perfectly level surface?


Thanks for your e-mail and question... I'll answer as best I can.

As for the Meade LX-10 or Celestar 8, I have no direct experience with either of these units, however, they are both good units and very comparable. I do know that both of them use the same optics as the more expensive scopes in their lines (in other words, the optical performance of the Meade LX-10 is the same as their highest priced 8" LX scope, and same for Celestron). The difference is in the mounting and accessories.

I can't really say which would be my preference without actually having used each scope for at least a few times. Almost every telescope has some "quirks" which are unique to the model. Both units can be upgraded with accessories for serious photography work. As equipped, the basic scopes can do some fairly sophisticated photography. If you plan on doing long exposure "through the scope" photography, you may possibly need (or want) an autoguider. I think these scopes are "autoguider ready", but you might want to fire an e-mail off to Meade and Celestron to verify this.

As for polar alignment, the tripod does not have to be level (but it will likely be easier with the kinds of mounts these scopes come with if the tripod is reasonably level). In reality, the tripod could be WAY OFF level; all that matters is that the polar axis of the telescope is parallel with the axis of the Earth's rotation. Polar alignment is important for long exposure deep sky photography. For such work, you may want to consider one of the "aftermarket" polar alignment aids to speed up this process. You can do very precise polar alignment with these scopes "as is", but it takes a fair amount of time. One feature that makes polar alignment easier is fine adjustment controls for the altitude and azimuth of the mount (not the same as right ascension and declination!). I do know that these scopes are adjustable in altitude (but I don't think that there is a "fine adjustment knob" for this task); I am not sure if the azimuth of the scope can be changed by loosening a control; it may have to be done by moving the entire tripod (a pain in the neck). From the picture of the Meade LX 10, it looks like it may have a control for azimuth adjustment without moving the tripod. For comparison, the scope I use (Celestron CG-11) has a mount that has fine adjustment controls in both altitude and azimuth, allowing for very easy polar alignment (regardless of the levelness of the tripod). Again, I have never owned one of the fork mounted scopes, so I cannot comment on the exact specifics of polar alignment.

If you plan to do photo guiding "by hand", it is important that the hand controller be able to do fine adjustment in both right ascension and declination. 2x seems a bit fast for this in my opinion (I usually use .5x). However, you could probably adapt to it pretty quickly. And , if you use the focal reducer (which makes the scope about F6.3), your guiding "errors" will be that much less evident. The "as is" scopes are F10, a bit "slow" for most photography work (but still manageable with the fast films available today). The F6.3 focal reducer (put out by Celestron for typically $120 or so) is a nice accessory, but not necessary for "openers". The basic scopes are 2000mm F10; the Moon will fit edge to edge (in the narrow dimension) on 35mm film with this configuration. At F6.3, the Moon would be very nicely composed on a standard 35mm film format.

One other thing: these scopes both "tout" being able to run on only 9v or AA batteries... that's "true" to a point. You WILL need a dew cap for these scopes, and more likely, you will need a corrector plate heater if you plan to stay out for more than an hour or two on damp nights. A corrector plate heater requires a heavy duty battery (or AC power supply). So, budget for a dew cap for openers (or make one from materials at home). Eventually you'll need some sort of a power supply (battery or AC) for serious photography work anyway, something to think about "down the line".

Either one of these scopes is far and away above the Tasco you have (had). You might try visiting Sky and Telescope's web site (www.skypub.com)... they have articles reviewing many telescopes, and the ones you are interested might have been reviewed by S&T (I can't remember offhand). Such articles could probably cover the details I cannot speak to.

Good luck, Joe Roberts

TOPIC: $450 budget... What telescope should I buy?


I am interested in buying a new telescope. I have $450 to spend, I know that I should get the most aperture for the money, can I get a pretty good telescope for this money? Is 80 mm aperture enough, what can I see with this amount? I look forward to hearing from you, thanks.


If you have $450 to spend on a new scope, I'd say a 6" Dobsonian reflector is your best bet. It will give images about 3 times brighter than an 80mm scope, which is quite significant. An 80mm scope is not bad, but dollar for dollar you'll see more with a good 6" Dobsonian.

Dobsonians offer the most "viewing per dollar" of any other type of scope. They are portable and easy to set up; this is important because you will use a scope more often if it's not a "pain" to deal with.

The 6" Dobs that are offered by a number of popular scope makers are all f8 optical systems. A 6" f8 optical system is the "classic" scope. It offers excellent "all around" performance. It will do well on planets and the Moon, and also has enough light gathering for good views of deep sky objects. A 6" scope is not one you will outgrow overnight. One other nice thing about a 6" Dob is that most of them are easily adaptable to other mounts should you want to do photography in the future.

There are several decent 6" Dobs on the market: Meade and Orion make ones that are very similar, and Celestron has one that is of a slightly different design. All of these scopes have received decent reviews in the magazines. They run about $350 plus shipping. You will want to be sure and get a few accessories: a finder scope (6x30 is the minimum recommended), an extra eyepiece, and a star atlas such as Sky Atlas 2000. All of this should fit into a $450 budget. If you spend a little more, you can jump to an 8" Dobsonian, you'll get even better views, but the scope will be a bit bigger and heavier. If in doubt, go with the 6" and accessories rather than a bare bones 8".

If you have not already done so, you should learn the basic constellations. You will need this knowledge to find your way around the sky. Knowing the sky will go a long way to making your new scope a pleasure to use.

A 6" scope will show you a lot (depending upon where you live of course). Assuming you can get to a reasonably dark sky, you'll be able to see all of the Messier objects, and many other deep sky objects such as galaxies, clusters (open and globular), and nebulae. You'll see detail on Mars (when it's close to Earth), Jupiter, and Saturn. The remaining planets will be easily visible but will show not much more than the basic shape (Pluto is the exception... you will be EXTREMELY challenged to see Pluto in a 6" scope even under very dark skies). In short, a 6" scope will show you many, many celestial objects.

Good luck... Joe Roberts

TOPIC: Edmund Astroscan vs. 8" Dobsonian


For years I have been using an Edmund Astroscan to casually observe. I am looking to upgrade to a Dobsonian, since I am not interested in astrophotography. From what I have read I am favoring an 8" f/6 from Orion, the new ones with several upgraded features. Do you have any experience with these, and how different will things look when I upgrade from my old 4" rich field scope? Thanks for your advice.


I have an Astroscan and have also used it for casual observing since 1984. It's a good scope when used for what it is intended for (rich field low power viewing), but it's not the best for lunar and planetary work. The views at powers higher than about 35x start to suffer. One problem is that it has no collimation facilities, so fine tuning of the mirror is not possible.

As for the 8" Orion Dobsonian, I have no direct experience with using the scope, but I have seen them (and looked through them) at star parties. It seems to be a very nice 'scope. It also appears to be very similar to the Meade 8" Dobsonian. The Orion Dobs have received good reviews in Sky and Telescope.

As for the difference between the 8" and 4.125", it will be quite substantial. The 8" is an F6 scope, which makes it "on the fast side of medium", where the Astroscan is F4 which is definitely fast. "Slower" scopes do not show optical path aberrations as badly as fast scopes, so if you have eyepieces which are not top of the line they will perform better in the 8". You will see substantially brighter images in the 8" as compared to the Astroscan. The 8" gathers nearly 4 times as much light as the Astroscan, which means things will appear to be about 1.5 magnitudes brighter (roughly the same brightness difference as exists between Jupiter and Saturn).

The 8" will be far better than the Astroscan for the Moon, planets and double stars. Being of much longer focal length, the 8" will allow you to get reasonably high power (say 100x - 150x) with ordinary eyepieces (a 9mm will give you about 133x, a decent power for planetary viewing). You will have to do "nudging" of the scope much more often than with the Astroscan, being that the field of view will be much less. One way to minimize nudging at higher powers is to use an eyepiece with a very wide apparent field of view. Eyepieces in this category typically have fields wider than about 60 degrees. They do suffer from more edge distortion than narrower field eyepieces, but high quality designs (like Televue Naglers) are really quite good in this respect.

On the low power end, you'll never get to the same true field of the Astroscan with the 8" Dob. If you use, for example, a 30mm eyepiece with a 50 degree apparent field of view, your magnification will be 40x, and your TRUE field will be about 1.25 degrees. This is far less than the 3 degree field of the Astroscan (with its standard eyepiece), but a 1.25 degree field is still quite nice and is wide enough to capture most of the large deep sky objects with a nice "margin" around them. The only way to get to a substantially wider true field is to modify the scope to accept 2" eyepieces (and some change to the secondary may also be needed, a task you probably don't want to attempt unless you are experienced in telescope design).

As for what you'll see (assuming a decently dark sky)... most of the major globular clusters (like M13, M3, M5, M22, etc.) will be resolved quite well and will be very beautiful (in the Astroscan they do not really resolve due to the low power view). Some galaxies will start to show structure (you'll see the arms of M51 faintly in a dark sky). You will be able to visually see a fair number of diffuse nebulae that appear around the sky. Many more planetary nebulae will be visible, but keep in mind that these objects are usually challenging because they appear to be very small in the sky. The views of planets will be far better than those in the Astroscan simply because you are able to get to high power without using super short focal length eyepieces coupled with a barlow lens. If you use a set of color filters, the views will be even better.

In short, the jump to an 8" scope from the Astroscan will be very substantial. While the Astroscan can only see a sampling of the objects depicted in Tirion's "Sky Atlas 2000", the 8" will be able to see most of them.

Hope this helps... Joe Roberts

TOPIC: Celestron G5, Polar Alignment, Setting Circle use


I just bought my first scope and put it together last night. It's a Celestron G5. I was wondering if you could give me some pointers on polar alignment for the use of setting circles. Please keep in mind that prior to the purchase of the scope I was doing a binocular survey of the sky which I just completed.


I am not personally familiar with the G5 (meaning that I have never used one), but I have seen them in the ads in Sky and Telescope. It's basically a C5 optical tube on an imported equatorial mount.

As for polar alignment, if you are planning to do only visual observing, the alignment need not be too exact. Basically, you want to aim the polar axis at the North Star as best you can by eye. The polar axis is the one that does NOT have the counterweight on it. The method involves getting down on your knees and sighting up along the polar axis to get the best aim at the North Star.

If you eventually want to do astrophotography (only basic astrophotography will be possible with the G5 mount), your polar alignment will have to be considerably tighter. To achieve this, you can invest in one of a number of polar alignment aids, or you can use what is know as the "declination drift" method (this method is tedious and time consuming but provides the most accurate results). I won't go into the method here because I suspect you are not really going to need it for your planned activities (at least not just yet).

As for setting circles, I rarely use them myself. They can be used to help locate objects, or at least to get you into the general area. Use of setting circles does require a fairly decent polar alignment ("eyeballing" it will probably not be adequate). Also, unless you have a motor drive on the RA axis that also turns the RA circle, you have to reset the circle each time you want to look for a new object. Most setting circles do not have too great of an accuracy (lines can only be etched so fine on the limited area available on small circles). Even on large telescopes they still have some error. I do not believe that the G5 mount has a motor drive as standard equipment. In either case, you'll have to first find one object without using the circles (after doing a decent polar alignment). Once you have the object in view (using a lower power eyepiece), you'll have to "set" the RA circle based on the position of the object you found (the coordinates of your object can be looked up in an atlas or catalog). For example, if the RA of the object is 15h 23m, you'll have to set the RA circle to that value as closely as you can. Because the RA circle is not turning automatically (it cannot without a drive), you'll have to quickly find your next object. If you wait more than 10 or 15 minutes, the RA circle will have drifted considerably with respect to the sky, and you will not be able to find the object you are looking for.

In short, setting circles are in my opinion more bother than they are worth. I personally like to use the "star hop" method to locate objects. Star hopping is a technique where you note the position of the object you are looking for with respect to some nearby stars. If there are no stars in the area, this method can take a little more work, especially if your sky is light polluted to the point where only a few stars are visible. I do not want to discourage you from trying the setting circles however. Just keep in mind that they will not make finding objects a "snap". Note that telescopes that come equipped with the so called "digital" setting circles can and do make finding things very easy, even with no polar alignment whatsoever! They come at a cost however... for my scope they were over $500!

TOPIC: Orion Explorer II eyepieces in an 8" Dob


I have a 60 mm refractor on an equatorial mount. I'm looking to upgrade to an Orion 8" f/6 Dobsonian. Do you think that their Explorer II eyepieces will work well on this telescope? Will I be able to get to 200x and obtain good detail of the planets using them? Hope you can help. Thank you for taking your time reading my question.


The Explorer II eyepieces by Orion are "entry level" quality eyepieces. They are far and away better than anything that comes with any "department store" telescope. I suspect that they will perform quite nicely overall with the 8" Dob. The Explorer II eyepieces have optical coatings (which is good); better eyepieces have "multi coatings" which improve light transmission further and help to keep contrast high (this is especially important for planetary viewing).

If you are planning a lot of planet viewing I might suggest investing in a set of color filters. Filters can enhance the viewing of planets in several ways. They help to cut glare, they help out when the "seeing" (air steadiness) is bad, and they allow improved contrast of certain features. Buying them in sets is the most economical way to get them if you plan to buy several. The "basic" set is great for most work.

Obtaining good clear views at high power in a reflecting telescope requires (assuming the optics are decent) that the telescope be properly collimated. An F6 telescope is what is known as "moderately fast" optically. The "faster" the scope is, the more precise the collimation has to be in order to have crisp clean images. The telescope manual will provide instructions on how to collimate the scope.

Overall the Explorer II eyepieces are decent. There are eyepieces that will yield noticeably better performance, but they will be *a lot* more expensive (like twice to three times as much). The more expensive eyepieces will have wider fields of view, a larger "sweet spot", better contrast performance, and less light loss. The only thing that you might have some trouble with: if you are trying for 200x in a 8" F6 scope, you are looking at using a 6mm eyepiece. The 6mm Explorer II eyepiece probably has limited eye relief, which basically means you'll have a harder time getting close enough to the eyepiece to see through it comfortably (this will be compounded even more if you wear glasses while observing). You might find it preferable to use a *quality* barlow lens in conjunction with one of the longer focal length Explorer II eyepieces to get to high magnification.

Hope this helps, Joe Roberts

TOPIC: A Meade ETX telescope for father and son


I'm planning on buying a telescope for my 6yr old and have lots of questions, and no experience in this field. What do you think of the Meade ETX?


My personal feeling is that a 6 year old will probably require the assistance of an adult when using the telescope... finding things in the scope will be tricky for someone this young. As an alternative, you might also consider a decent pair of binoculars... a 6 year old will have no problem using these.

The ETX would be a great starter scope... albeit a bit pricey at $600. Keep in mind that it only comes with a "tabletop" tripod; most people find these less than convenient. "Real" tripods are available, or if you have a heavy duty camera tripod you could likely use that.

The ETX is not necessarily a "beginner" telescope... I know a number of people who have them as a compliment (and portable option) to their much larger scopes. It has received good reviews, and the people I know who have them have stated that they indeed do provide very nice images.

The ETX would be far and away better that the typical 60mm refractor "beginner" telescope. It is a unit that could stay with you (and your son) for a lifetime. It can also be used as a powerful telephoto lens (it could be used to take close up photos of birds for example).

One word of caution: NEVER look at the Sun with any telescope unless you have the proper filters and are certain of how to use them! Permanent blindness could result if you look at the Sun with an unfiltered telescope.

Observing Technique Q+A

TOPIC: Observing Mars


I'm new to astronomy and I'd like to look at Mars with a telescope. What's the best way to go about seeing Mars?


The planet Mars is usually a disappointment to first time viewers. At best it only obtains about the same visual diameter as the ball of Saturn (not the rings). Typically, Mars is only 6 or 7 arc seconds wide, too small to see any real detail unless (a) you have a very steady night and (b) you have preferably a large high performance refractor.

Mars is best seen when it is at or near what is called opposition (the point in its orbit when it is close by to Earth). Interestingly (and unfortunate for us northern viewers), Mars always has its best oppositions when located in the southern extremes of the ecliptic (this happens for reasons I cannot explain, perhaps some kind of planetary orbital "resonance"?). So, when Mars is "biggest" it's always in the south, making for crappy seeing and limited visibility. Figures!

As for viewing Mars, you can see some pretty nice detail when it is at opposition, and there are some things I can recommend. The biggest problem with Mars is its blinding brightness! It causes so much glare that detail tends to be missed. Any scope larger than about 6" will certainly cause some severe glare (I've had glare problems with a 4.5 " Newtonian). To help see detail, I use an orange or red filter to cut the brightness. Another good filter (believe it or not) is a Moon filter (the one I have passes only 13% of the light, and being a neutral filter it preserves the color balance). I find the Moon filter works quite well when used with the 11" scope I have.

Because Mars is small, you'll have to use at least 100x magnification; I've used powers in the range of 250x - 300x in my 11" scope for nice views (on nights when seeing permits such powers). But again, some kind of filter is a virtual necessity.

Schmidt-Cassegrain reflector (SCT's) are not the best instruments for dealing with objects of extreme brightness and subtle features... this is because of their relatively large (33% by diameter) central obstruction. The central obstruction causes a reduction in contrast; the larger the obstruction the worse the contrast. I don't understand the technical reasons for why this is so, but there was a detailed article about it a few years ago in S&T if anyone cares to dig into it. Despite what the theory says, I have had some very nice views of Mars with my SCT; the best views were obtained with the help of various filters. If you don't have any filters, you might be able to use a neutral density camera filter (assuming you have one of these). It will be a nuisance to hold it in place, but it's worth a try...

I've seen some detail on Mars (when it was close a few years ago) using a 4.5" Newtonian. I was able to spot some surface markings and even a polar cap with this modest instrument... I have heard of people spotting clouds in the Martian atmosphere, but I have never seen any for certain (these clouds are low contrast and appear to be very challenging objects).

Finally, I have occasionally been asked if I've ever seen the Moons of Mars. The answer is no. In theory, they should be easy targets for an 11" scope based on their brightness (about magnitude 13), however, the excessive brightness of the planet so close by dictates that a much larger scope is required to spot them. Keep in mind that the closer of Mars' two Moons orbits only about one planet ball diameter away from the planet!!! The planet outshines (or should I say out reflects) the moons by a factor of roughly 50,000. In summary, for the best views of Mars, look at it when it is at or near opposition, use high magnification, wait for a steady night, use some kind of optical filtering, and use a decent telescope!

TOPIC: Seeing the Horsehead Nebula in an 8" Scope?!?


There is one question dogging me to which I can find no answer that I can understand. The Orion 8" reflector with an equatorial mount is advertised to be able to see the Horsehead Nebula, something I couldn't even get close to with the Dob of the same aperture. What's up with this?


As for the Horse Head nebula in an 8" scope... I can say two things. First, whether the scope is equatorially mounted or Dob mounted should have no impact on the optical performance of the unit (the equatorial mounted scope will be easier to track with however).

Seeing the Horse Head visually in an 8" scope would be a major accomplishment (unless you live in INK black skies with limiting naked eye magnitude of 7 being routine). A few years ago I had an opportunity to search for the Horse Head under some decent skies. With my 11" SCT *and* a Lumicon H-Beta filter, I was just barely able to detect the cloud in which the Horse Head resides! There was a 25" scope nearby, so I tried looking with it. With the 25" scope and the H-beta filter, the Horse Head was pretty easy to see with my eyes (although a newcomer did not find it particularly obvious). In the 25" *without* the filter the nebula became much more elusive... visible but it did not jump out at you. And keep in mind that the Lumicon H-beta filter is optimized for the Horse Head nebula! Based on all of this, using an 8" without a filter to actually see the nebula would be a formidable task. I'm not saying it cannot be done, but to have a decent chance you'd need to be under superlative skies.

Miscellaneous Q+A

TOPIC: The "name" of our Solar System


What's the name of our solar system? Just wondering and I can't seem to find the answer.


I believe that the name of our solar system is just that... "The Solar System". I do not recall ever having heard it called by another name. On the other hand, our galaxy does have a name, the "Milky Way".

Hope this helps, Joe Roberts

TOPIC: Why doesn't the shortest day of the year have the earliest sunset and the latest sunrise?


Why don't the latest sunrise and earliest sunset occur on December 21?


This is due to the eccentricity of the Earth's orbit. Consider the moment exactly between sunrise and sunset. You might think this would be exactly midnight at any time of the year. But this is not so. During the winter, the Earth is moving abnormally rapidly in its orbit so the sun appears to move farther than normal per day against the background stars. As a result of this, it takes the Earth a bit longer than normal to rotate into the position where the sun can rise. (The Earth's rotation rate is constant at all times of the year). This slight deviation tends to accumulate and after several weeks will cause the sunrise to be abnormally late. Similarly the sunset will be abnormally late as well..

In the summer the Earth is moving a bit more slowly in its orbit than average so the situation will correct itself and then swing in the other direction. In effect the "true" midnight varies by several minutes on either side of the clock midnight depending on what time of year it is. This variation is called "the equation of time." When the true midnight is after clock midnight, the sun will tend to rise late and set late. When true midnight is before clock midnight, the sun will tend to rise early and set early. Superimposed on this, of course, are the seasonal variations we see due to the tilt of the Earth's axis of rotation relative to its orbit. The length of the day and night is controlled by that tilt, but the precise moment of midnight fluctuates due to the effect I'm talking about here. The combined effect of these two things causes the sequence that you see: earliest sunset, longest night, latest sunrise. I don't know how clear this explanation is, but basically that's what it's about.



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