Two Methods of Telescope PhotographyAfocal - The most inexpensive method of taking photographs through a telescope is called afocal. This means that you focus the telescope on the object you want to photograph and then point your camera into the eyepiece to take the photo. This method works well for point and shoot cameras and cell phones. It is highly dependent on the size of the eyepiece for your telescope. The larger the eyepiece, the easier it will be to aim the camera and avoid vignetting. The trickiest part about the afocal method is keeping everything steady. For light cameras you can tape the camera to the telescope (carefully please). For larger cameras you may need to use a tripod.
Prime Focus - A slightly more expensive method is prime focus. For this type of photography you'll need a couple of added pieces of equipment. You'll need a TRing and a TAdapter designed for your camera and your telescope. These should cost around $25 each. These pieces of equipment will allow you to attach your camera directly to the telescope without the lens or eyepiece. This method allows for sharper focus and less time spent lining up the camera with the telescope for each shot.
Additional Telescope Photography TipsMinimal Focusing Distance - Remember that your camera lenses have minimal focusing distances. A small focal length lens usually has a smaller minimum focusing distance and will be easier to use in conjunction with the telescope because you can put the lens closer to the eyepiece. If your lens has a macro setting, this will help reduce the minimum focusing distance.
Manual Focus - If your camera has manual focus this will help you get a sharper image through the telescope. Smaller lens cameras such as cell phones generally handle the autofocus fine but larger lens cameras like DSLRs see a good bit of the area around the eyepiece and will have trouble using autofocus.
Shutter Shake - If your telescope is not a large heavy one, the shutter motion on your camera might cause shake with using the prime focus method. You can minimize this with good support for the camera. You can also lower your film speed and up the time the shutter is open so there is more stable recording time to overpower the time it shakes.
The Moving Moon - The higher the magnification, the more apparent the movement of the moon will be in your photography. If you have a 1000mm telescope and a doubler on your camera the moon motion could be apparent in just a few seconds. Experiment with exposure times to see what works best for your particular set up.
Exposure - As we discussed in our basic moon photography lesson, it is ok to underexpose the moon a bit. Even with the light lost through the telescope, the moon is so bright compared to the sky around it that the camera may overexpose the moon in trying to brighten the sky.