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 Can I use my NexStar GT - GTL telescope for photography?
Answer Yes. Your telescope can be used in several ways to take photographs of celestial and even terrestrial objects. 

The most basic way is to use the telescope as a piggyback mount, so-called because the camera will ride piggyback on the telescope. In this type of photography, the camera lens takes the picture, not the telescope lens or mirror. The telescope acts as a platform and can be used to provide tracking if the scope has been polar aligned.  

NexStar GT refractor and reflector models don’t have built-in capability to piggyback. Rings equipped with a 1/4x20 screw and counterweights are available in the aftermarket for piggybacking on these scopes.  Mount the rings around the scope’s tube, place your camera’s tripod socket on the screw and turn it until it is securely onto the thread. Align the camera in the direction of your subject – generally that will be parallel to the telescope tube’s axis. Lock the camera in position on the screw. Add a shutter release and the camera is now ready for piggyback photography. 

Another basic way is prime-focus photography. For this you need a T-adapter to attach to the scope and a T-ring to attach your SLR camera. A T-adapter with a 1-1/4” eyepiece barrel is very versatile and will slip into the eyepiece drawtube of most telescopes. (The 4, 102 and 130 GTs come with a T-adapter as a part of the 1-1/4" eyepiece holder.) Other types of T-adapters with threads are specific to certain types of scopes. The threads on the T-adapter will fit into all T-rings. Since each brand of camera has its own specific thread size or bayonet type, you need to get the proper T-ring. Thus Canon has its T-rings (two of them); Nikon has its own T-rings; Minolta has their own specific rings, and so on. Any camera store will have T-rings for most popular makes. Attach the T-ring to your camera, then the T-ring to the T-adapter and slide the 1-1/4” barrel into your eyepiece holder. Add a shutter release and the camera is now ready for prime-focus photography.

Again, the telescope acts as a platform and can be used to provide tracking if the scope has been polar aligned. Tracking may not be needed for very short exposures of the sun, moon and planets.
 

IMPORTANT NOTE: For the Newtonian models 114 GT and 130 GT, the focal plane of the telescope may not be far enough from the tube to allow you to focus with the T-adapter/camera setup you are using.  Try using a T-adapter with a built-in Barlow lens (with the lens at the forward end), such as Celestron’s #93640 to extend the focal plane to reach your camera’s imaging plane. Another way that will achieve infinity focus with almost any Newtonian or other telescope is eyepiece projection directly into your camera with Celestron’s #93230 8-24mm zoom eyepiece. Since the eyepiece has T-threads under the eyecup, simply thread it into your T-ring and then attach to your camera and put the assembly into your scope’s eyepiece drawtube.



A third way is to use a point-and-shoot digital camera with the universal digital camera adapter. Here the camera is held by the adapter behind the telescope’s eyepiece. Attach the adapter’s clamp to the eyepiece drawtube, then the camera to the platform on the adapter. You will have to make adjustments to the universal camera adapter to properly position the camera lens in the emerging light beam from the eyepiece and focus it. This is easy to see with the camera’s preview screen. Try different eyepieces in the telescope and zoom settings of the camera to get the view you want.

You can also use an electronic eyepiece or webcam type camera like NexImage. These cameras often have nosepieces that fit directly into the 1-1/4” eyepiece drawtube with no adapter needed. The electronic eyepieces output directly to a TV monitor, while the NexImage webcam-type requires a computer to see and capture images.



Article Details
Article ID: 1716
Created On: Feb 21 2005 07:32 AM

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