First light

This photograph is labelled "First light" because it's the first time we've used the Canon 10D with our telescope, a Meade ETX125EC. Attaching the camera needs a T-ring adapter, which took some time to get hold of.

The camera was at the telescope's prime focus, attached to the rear port, so the scope is just acting as a rather large telephoto lens, in this case with a focal length of 1.9 metres. There's no eyepiece involved. To reduce vibration, we used the self-timer and the mirror lock-up feature on the camera. The shots were taken from indoors, on a window shelf ... not usually recommended! The focusing wasn't perfect (that's one of the hardest parts of astrophotography), and the moon was low.

The exposure here is 1/125sec at ISO 400, short enough that guiding isn't necessary. It's very easy to overexpose the moon -- always remember that it's a sunlit surface (albeit a rather dark one), and exposures of around 1/30 to 1/125 sec will usually be OK. This explains why you don't see photographs of the moon in a starfield, other than during a lunar eclipse -- the exposure's just too short to capture stars.

If you're not sure, underexpose. This can be corrected in post-processing, but there's nothing you can do with an overexposed image.

This is a 1/3-scale montage of two shots; the moon won't quite fit in one frame when it's nearly full. Montage was done in Composition with some post-processing in Photodesk: colour balance, some sharpening (a bit too much, in fact) and a small gamma adjustment to brighten it up.

ROCchart has a very useful 'field of view' (FOV) indicator, which will show you what you can actually see through any particular optical insrument. The picture below is a screen grab of the program, showing how the FOV dialogue is set up for the combination of Canon 10D and the ETX125 telescope.

The lilac rectangle is ROCchart's FOV indicator. The Type is Box aperture -- for binoculars you might choose Circular field. The scope's focal length is 1900mm, and the chip in this particular camera is 22.7x15.1mm; for a 35mm camera you'd enter 35x24mm. The inset picture is an actual (uncropped but scaled) photo, so you can see how accurate it is. The terminator is in the right place, too. The small amount of rotation is caused by the camera not being quite level.