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PAUL ZENOFSKI ASTRO COMMENTS
Questions and answers
Your editor has asked me to deal with some of the more common
astronomy questions as he has been getting emails from readers who are
basically beginners and would like some simple explanations. So here
John Freedman from Doncaster asks: “How do I use my camera with a
Paul: “This is probably one of the most common questions I am asked by
beginners in astro observing and there are several answers. So where do I
“Well, firstly, I am assuming that you intend using a single lens reflex
camera, and here you might think that just pointing your camera up into
the sky would be sufficient in some cases. Well, ‘yes’ and ‘no’ is the
answer here. In its simplest form you can attach any SLR (or DSLR) camera
to your telescope, a sort of ‘piggy-back’ arrangement, simply pointing and
shooting along the top or side of the ‘scope. This works well for general
overall views of the sky, but is not totally specific and most modern
mountings on telescopes usually have a provision for this 'complete sky'
OR USE THE TELESCOPE AS YOUR LENS
“You can remove the camera lens and then attach the camera body in place
of the eyepiece of the telescope, using the latter’s focusing mechanism to
make the viewed object sharp: this method is termed the prime focus
system. In other words the telescope itself acts as a camera lens”.
(Photo: camera with its own lens removed and replaced by the telescope.
Mounting rings are readily available for this method)
“Or, slightly more complex, you can use what they call ‘eyepiece
projection’ where a standard telescope viewing eyepiece is retained and
the camera body is introduced behind this in order to obtain a more highly
“Now it will be obvious from the above that the first system is the
easiest to use but this will, of course, limit your results to what can be
seen through the cameras own lens. The second method increases the
versatility of the set up. And the third takes it a stage further. If you
are a beginner I would, initially, recommend Method One until you become
accustomed to setting exposure times etc”.
“Next time I will deal with getting the right exposure. But remember that
astro exposures can take up to 2 hours or more and this, in turn,
introduces other problems”.