Updated 11 November 2000

Joe Roberts Astrophotography

Technical Articles: Astrophotography for Beginners


Introduction

Have you seen some of the amazing photos that amateurs have taken and wish you could do the same? This article will help to get you started. In truth, astrophotography is a very specialized and demanding form of photography that can take years to master. The good news is that astrophotography has never been easier (mostly due to the vastly improved films available today). Even a beginner can get a shot today that would have been the envy of seasoned astrophotographers from the 1970's! Basic astrophotography takes only a minimum of special equipment, so you can get started with only a small investment.

This page now contains information on the following two types of astrophotography:

Additional articles will be added as time allows...

Don't think you can do it?

Check out what nine year old Meredith Lorenz did on her first attempt by clicking here.


Wide Field Fixed Tripod Astrophotography

Wide Field Fixed Tripod Astrophotography is the simplest form of astrophotography. It is the ideal starting point because it takes only basic equipment, and even "first timers" can get very nice results!

Getting Started: Equipment You'll Need...

The Camera: To do astrophotography, it should be obvious that you will need a camera. What is not necessarily so obvious is the type of camera that is best suited to astrophotography. In short, the more "idiot proof" a camera is, the more the likelihood that it is not well suited to astrophotography! "Point and Shoot automatic do everything" cameras are not suitable for astrophotography. The best camera to use is a manual 35mm SLR camera. The following features are a must for any camera, which is to be used for astrophotography:

  1. The camera should have removable/interchangeable lenses (most any SLR will meet this requirement)
  2. The camera should be of the type that allows the shutter to be operated in all modes (time exposure mode especially) even with the battery removed!
  3. The camera must have the ability to do long time exposures (usually the "B" setting)
  4. The camera should have the ability to accept a remote shutter release cable
  5. The camera must have a tripod mount threaded hole on the bottom

If you have a camera where the light meter is broken, no problem (you'll not need it for astrophotography).

There are many cameras available that meet the above criteria. One good camera for astrophotography is the Pentax K1000. It is a very basic but quality camera that fits the bill perfectly (and it has been around for a long as I can remember). The K1000 can be found (body only) for around $150 (US) through mail order. Other cameras that are good for astrophotography are the Pentax ME Super, Canon FT, and Nikon FM. Note that there are many more, the ones listed are ones I have experience with. Note that in my opinion the best SLR cameras for astrophotography are often the simple, "low end" models. If you purchase a $2000 high end Nikon, it will not likely take an astrophoto that is any better than one taken by the $150 Pentax K1000 (it is the lens quality that matters most). In fact, the fancy features of a high-end camera will probably make it non-ideal for astrophotography! Stick to a simple, basic (but quality) camera for starting out in astrophotography. If you do not have a camera that can be used, the Pentax K1000 is the perfect model to invest in (and it also takes great "regular" pictures too)!

The Lens: For basic astrophotography, a "standard" 50mm lens is a great place to start. Most 35mm camera packages come with a standard 50mm lens. The quality of lenses can and does vary. One thing is certain: astrophotography is probably the most demanding test you can give a lens. Fortunately, most lenses today seem to be of pretty decent quality. Higher quality lenses will often have faster "F" ratios (like F1.4 or 1.2), they will have premium optical glass, and enhanced anti reflection optical coatings (these help to improve contrast). The purpose of this article is not to go into the full details of what makes a good lens however. If you are just starting out, most of the standard 50mm lenses that come with a basic SLR kit will more than likely take a decent astrophoto. Such lenses sell for between $50 and $100 (US). Another lens that is good for a beginner is a 28mm "wide angle" lens. Such a lens will allow you to photograph a larger are of the sky in one shot.

What about zoom lenses? While in my opinion not the lens of choice, zoom lenses can take decent astrophotos also. Many camera outfits today come with a zoom lens with a range of say 28mm (wide angle) to around 70 or 80mm (mild telephoto). Zoom lenses typically have more optical elements than their fixed focal length counterparts, and therefore are more susceptible to aberrations (assuming all other things equal). In my opinion, fixed focal length lenses are the way to go for astrophotography, but don't let this discourage you from experimenting with zoom lenses. They can allow you to take decent photos.

Tripod: For even the most basic astrophotos, you will require a tripod. The tripod does not have to be exceptionally expensive, it just has to be able to hold the camera steady. This is because many astrophotos require exposures of 30 seconds or more. The tripod should have enough degrees of motion to allow you to easily point the camera at any portion of the sky.

Shutter Release Cable: In order to take photos without vibrating the camera (and thus ruining the photo), you will need a shutter release cable (preferably the locking type). These can be picked up at most any camera store for around $10. Try to get one with a long cable (several feet is ideal). Shorter ones are OK if you are extra careful not to vibrate the camera while the shutter is open.

Film: Choosing the proper film is probably the single most important variable for beginning astrophotographers. This article mentions only print film (I have little experience with slide film). In addition, there are numerous types of film available to astrophotographers. I will suggest only those that I have worked with and know that produce good results. For color prints, the following films are excellent for those just starting out: Kodak Royal Gold 1000, Kodak Royal Gold 400, and Fuji Super G800. For B+W prints, try Kodak TMAX 400. All of the above films are commonly available at most camera stores (the best prices I have seen are at Wal Mart). Note that if you use the Kodak color films, you want the Royal Gold, not the "plain" Gold! It costs a little bit more, but it really is better for astrophotography.

Miscellaneous: You'll need a few other items, but most of these you probably already have. To time your exposures you'll need a stopwatch (a wristwatch with a second hand is fine). Having a pad and pen to keep records of the work you've done is a good idea. Your notes will help you to later sort out what you've taken, as well as what worked well and what did not work...

Your First Astrophotos...

Your first astrophotos should be of an "easy" target such as a constellation. This type of astrophotography is known as "Wide Field Fixed Tripod" astrophotography. For these shots, you'll not need a telescope of any kind, just the items listed in the section above. Load the film (I recommend color film for your first shots) into the camera and advance it to the first shot. Mount the camera on the tripod and install the shutter release cable. Set the F-stop on your lens to anywhere between F2 and F4 (but do keep notes), and be sure to set the focus to infinity! Aim your camera at a part of the sky where there are the most bright stars visible (Orion is an excellent target if you are starting in fall or winter). Try not to aim the camera in a direction where there is a lot of skyglow (caused by light pollution); in addition, make sure that no streetlights are shining directly on the camera lens (otherwise "ghosting" and poor contrast images might result). Then, open the camera's shutter and begin timing your exposure. At the 15 second mark, end the exposure. Advance the film and then take another shot of the same area, but this time make the exposure 30 seconds. Try another exposure at 60 seconds. Do the same thing but try a different F-stop. Repeat this procedure for different areas of the sky. Be sure to try and take at least a few shots of the polar region! For one shot, set the lens F stop to around F8, and take an exposure of an hour or so (this will result in a very interesting effect due to the Earth's rotation).

Once you have finished the roll, the question now becomes "Where do I get it processed?" In my opinion the best place to take astrophotos (for beginners anyway) is to a "one hour" photo processing place. The reason is this: you will be able to personally give instructions for processing to the person who will do the actual developing and printing of the film. If you send a roll out to a mail order house, chances are better that your written instructions will be "lost" and something bad will happen. When you bring the film in for processing, tell the machine operator that the photos on your roll of film are astrophotos. Also mention that many (if not all of them) will be very dark compared to "regular" shots; tell them to print every exposure (regardless of what the machine thinks), and tell them not to cut the film (negatives)! The reason for requesting that the negatives not be cut: the borders between the frames of astrophotos are often hard to detect at a casual glance, and the operator may inadvertently slice in half an otherwise very good shot (this has happened to me). More than likely, the prints you receive will not be perfect the first time around. The prints will probably need some darkening or lightening, and they may need some color balance. Once you do have a good shot, keep it handy as a reference to show the operator what the photos should look like in general. Most of the "one hour" photo shops I have dealt with have been very cooperative and are often willing to do corrections for no extra charge. I have had good luck with "Ritz Camera" and "Russell's 60 Minute Photo" (note that individual franchises do vary in the quality of their work however). Your first roll might not be perfect, but chances are that you will have at least several very nice shots from your very first roll!

If you try B+W film for your first astrophotos, your processing options will be more limited (unless you have a home darkroom). The reason is that few (if any) "one hour" processing shops do B+W on site. The vast majority of B+W processing is sent out to commercial processing houses. In my experience, B+W film that is sent out gets processed in a "generic" way that is not really suited to astrophotography. If you have a home darkroom, you have much more control over the final result. If you do have facilities for processing B+W at home, by all means try some B+W astrophotography!

Assesing the results... Your first roll may not be perfect, but chances are there will be at least a few decent shots. Do you notice that the stars appear as tiny streaks even on the short exposures? Although it does not seem to, the Earth really does rotate enough to leave a short star trail even on a 30 second exposure! Notice also that the longer exposures may have recorded more stars (especially if the camera was aimed at the polar region and/or your sky is very dark). Do you see unexplained "ghosts" in your images? If so, this can be caused by stray light (from nearby streetlights or floodlights) that is scattered by the camera lens. The remedy for this? Be sure that your camera is completely shielded from stray light sources. Are your photos washed out to the point where it looks like they were taken in twilight? If so, the light pollution in your area may be the problem (you'll have to get to a dark sky area to eliminate this problem). Do you see the various colors of the stars? If you took a photo of the constellation Orion you should see both red and blue stars (film is great for capturing star colors as compared with the human eye). Your photos may suffer from other aberrations, but I've covered the major ones.


The Next Step:

Piggyback Astrophotography

Piggyback astrophotography is the next logical step in your astrophotography activities. It will however require a reasonably sophisticated telescope; hence the cost of doing this next step represents a substantial jump up from the fixed tripod type of astrophotography. Piggyback astrophotography is so named because the camera is mounted "piggyback" on the telescope optical tube; the telescope basically acts as a tracking platform for the camera (you are not taking photos "through" the telescope). The piggyback method allows one to take much longer exposures of the stars without having to worry about the stars making "trails" on the film. Some very impressive shots can be obtained via piggyback photography. This article will cover "basic" piggyback astrophotography ("basic" meaning that guiding eyepieces and drive correctors are not used, and camera lenses are limited to 28mm to about 210mm).

Piggyback Astrophotography: What you'll need: To do basic piggyback astrophotography, you'll need the following:

  1. Camera, lenses, and film as described above
  2. Shutter release cable
  3. Equatorially mounted motor driven telescope
  4. Camera mount bracket

Items 3 and 4 require more elaboration. The telescope you will need must have an equatorial mount and it must have a motor drive. In order for the telescope to act as an accurate tracking platform, you must be able to do a fairly accurate polar alignment; the degree of accuracy depends upon the focal length of the lens you intend to shoot with and the length of the exposures you plan to try. In general, short lenses and short exposures are less demanding on the degree of polar alignment accuracy.

Item 4, the camera mount bracket, is required to mount the camera to the telescope's optical tube. For many telescopes, mounts are commercially available. You can also make one yourself; it does not have to look "pretty", it just needs to be stable and have the ability to hold the camera securely such that it does not allow the camera to move with respect to the telescope's tube assembly.

Piggyback Astrophotography: Your first attempt The following steps will outline the procedure for doing piggyback astrophotography:

  1. Prepare the telescope: The first thing to do is to set up the telescope and perform a polar alignment. If your telescope does not have a polar alignment aid, this can be a time consuming and tedious task. "Eyeballing" the polar alignment will generally not do unless you keep exposures short (a minute or two). It's probably best to consult your telescope's manual if you are not familiar with the procedure for doing polar alignment... there are so many methods (some better than others for a given scope) that I cannot realistically cover them all here. Once you have a decent polar alignment, be sure not to bump the telescope mount!
  2. Prepare the camera: The next step is to load the film into the camera and advance it to the first shot. Select the lens you want to use (do not use a telephoto for your first attempt) and mount it on the camera.
  3. Mount the camera on the telescope: If not already in place, install the camera mount bracket onto the telescope tube (try to mount the bracket at a point on the tube near where the tube is attached to the telescope mount). Once it is secure, mount the camera securely on the bracket. NOTE: The telescope balance will be significantly altered by the additional weight (especially because the weight is placed away from the tube). Use caution to make sure that the telescope tube does not swing out of control as a result of the additional weight. Perform a "rough" rebalance of the telescope (do not spend a ton of time doing a precise balance at this time). Note that the camera does not have to be lined up with the telescope tube!
  4. Aim the Camera and balance: Move the telescope's tube such that the camera is pointing to the area of the sky you want to photograph. Depending on your camera bracket, you may have to make some adjustments to frame up the area you wish to photograph. Once you are satisfied with the framing, it is time to do a precise balance of the telescope. Why did we not do this before? The reason is that the telescope balance can be made optimum only for certain positions (because of all the extra weight hanging off the telescope at a strange angle). We want the balance of the scope to be optimum for the area of the sky we are trying to photograph. Once you have the balance tuned up pretty well, make some slight adjustments so that the balance of the telescope tube tends to make the optical tube move slightly to the west. Why do we want this? Because it will ensure a good mesh of the telescope RA axis drive gears. If the balance is "perfect", backlash in the RA drive gears can become a problem. Once all is set, be sure to lock the RA and DEC axii of your telescope! Note that if you move the telescope to a new part of the sky for your next shot, you'll have to rebalance the system as described. Hint: Take all of your planned shots of a particular part of the sky in sequence!
  5. Take the photo: Make sure your telescope's drive is running. Also make sure your camera lens focus is at the proper F-stop and make sure the focus is at infinity. CAREFULLY open the shutter using the remote cable release. GENTLY let go of the cable release... if you let go of it and it hits the telescope tube, a vibration can result which can mess up an otherwise decent shot. Time the exposure; when the time is up, again, carefully stop the exposure using the remote cable release. Advance the film to the next shot. Hint: for every shot you plan, take at least 2 shots of the same area. Why? Sometimes a shot can be messed up because of dust, airplane trails, or poor handling at the photo lab. It's no big bother to take two shots of the same area once you've got everything all set up (setup is 75% of the work!).

How long of an exposure can be made? That depends upon how accurate your polar alignment is, how good your telescope's drive is, and the ambient sky conditions in your area. In addition, you have to take into consideration the focal length of the camera lens you are using. If it is a "short" lens (like a 50mm or 28mm), you can probably expose for up to 15 or 20 minutes if your polar alignment is good, your drive is of high quality, and your sky is reasonably dark (assuming ISO 400 speed film and a lens F-stop of about F2.8). Longer lenses will "magnify" the errors in your alignment and your telescope's drive. Each telescope will be different in this regard... experimentation is probably the best way to become familiar with what "works" and what doesn't with your particular setup (remember, this is astrophotography, an activity where trial and error is a fact of life). For starters, I'd suggest exposures of 1, 2, 4 and 8 minutes. If those work well, you can work up to longer exposures (to perhaps as much as 30 minutes).

Processing of film for piggyback shots is the same as described above. Assuming that nothing went terribly wrong, your first piggyback shots should show significantly more stars than your fixed tripod shots. Did you take shots that had scenery in them as well (trees, houses, etc)? If so, you'll notice that the objects on the ground are blurred as a result of the telescope tracking. This brings up one of the advantages of fixed tripod shots (the ability to have both ground and sky objects not blurred).


More to come...

I will at some point extend this article to cover more types of beginning astrophotography. Topics to be included: Advanced "Piggyback" astrophotography, "Afocal" astrophotography, Lunar "though a telescope" astrophotography, and "Deep Sky" photography. Articles will appear as soon as I have time to write them! In the meantime, feel free to submit questions. If I am qualified to answer, I will!


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