I hooked the Canon A70 to the laptop while it was mounted on the telescope in order to get an idea of the best ways to use it for astronomy photos. The lens is a 40mm and the telescope is focused on a branch about thirty feet high and a hundred feet or so away.

This photos series shows six zoom steps of the camera lens, starting with no zoom to maximum zoom. The only other change I made was to try and obtain a good focus for each zoom. In photoshop I shrunk the photos down and put them together, but otherwise no color balancing or sharpening.

As I've mentioned before, Canon includes remote control software for the camera. The software allows complete control over the camera settings (including zoom) and a little "live" preview window. Well, it's not totally live or totally accurate. In order to send the image over slow USB 1.0 (why don't cameras use firewire??!!) they compress the heck out of it and only allow for a small thumbprint preview window. I'm not sure which is harder to focus with, the on-camera screen or the remote window.

Taking photos this way is kind of slow. Instead of storing them on the camera the Canon software takes the snapshot and then downloads it over USB. It's kind of funny to see the estimate of free space as room enough for 6,000 hi-rez pictures. Still, it's workable and a fair sight better than the alternative (no control, no view). I wonder if an iSight could be repurposed as a telescope camera? (of course...)

The first thing I noticed was that without zoom there's this dark elliptical area on the right side of the image. Gently twisting the camera/lens/telescope assembly will make it worse or almost get rid of it entirely so I bet it's an alignment issue with the dozen or so lenses that the light is winding it's way through. I haven't found an adjustment combination that clears it up without assistance.

Once you start zooming in the darkening fades a bit and moves more to the right.

Zooming in on the images in photoshop I can see that it's not quite focused or something else is slightly off. Maybe it's Chromatic Aberration? (redder colors bend less than blue colors so you see rainbow of colors around the image) Or maybe I just didn't get the telescope focused. Hard to say. I probably ought to re-check the telescope's collimation. Collimation is the alignment of the front lens assembly in order to maintain a straight light path through the telescope and into the eye piece.

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