Astrophotography for Beginners Part 2

Posted by Kieron McGrath - 16:01 on 29 July 2011

The second method of taking photographs with a telescope is known as Prime Focus. Using this technique the telescope replaces the camera's lens. So if you
have an 80mm f/4 refractor for example, your camera will now be attached to a 320mm lens. This will give you a magnified image and a narrower field of view.

The camera is connected to the telescope via a T-adapter and T-ring. The T-thread is 42mm and has long been a standard in the astronomical field. T-rings are
camera specific so you will require a T-Canon EOS, T-Nikon or T-Minolta ring, depending on your make of camera. Many telescopes now come with a T-thread on
the focuser so you won't need a T-adapter.

The final way of using your camera with the telescope is known as Eyepiece Projection. This uses the manifying power of the telescope plus an eyepiece. The
camera is mounted over the eyepiece and photographs the image that your eye will see.

For fixed lens camera's a mechanical device such as the Orion SteadyPix Camera Mount is used. With DSLR's you can use an Orion Variable Tele-Extender (see below) and a
T-ring. The tele-extender fits into the telescope focuser and the eyepiece slides into the extender. You can vary the size of the magnified image by moving
the extender up or down. Eyepiece projection is the best way to image small objects such as the planets,

Call or email me if you have any questions about astrophotography.

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