[LeoTaylor]

I wonder how a distorted image would be recognized. It doesn't show in the Fourrier space. As for the wear, I wouldn't mind at all.
The wear on 100 shutter activations for a K20D is about exactly as expensive as ordering a 5x7 print. The time and wear on the harddrive needed to stack'em all would be a larger concern

Hello FalconEye,

I don't know how the software works internally but I have heard of using transforms to determine detail as you suggest. I also have heard of using the algorithm from creating a compressed JPEG. It seems the better detailed an image, the larger the compressed image. I suspect deviation of the selected match points from the reference image is included, which would catch some distortions. K3CCDSoft displays a list of frames sorted by "quality", and the distorted ones are near the bottom.

You have an unusual method of putting a value on wear and tear. Here is how I measure it:

I consider the percentage of total life time taken up by the astrophotography shutter clicks. As mentioned, when photographing Solar objects with a web cam I take a LOT of frames. In one session I'll take 5-10 videos of 600-1200 frames (60-120 seconds at 10 fps each). It takes me that many to get one good video and average out atmospheric distortions. I live in Connecticut, a still night sky is non-existent. That comes to an average of 6000 images per session. I do several Moon, Saturn, and Jupiter sessions per year and Mars every other year. No one is sure how Pentax rates the K110D but 150,000 shutter clicks seems to be a typical value. Thus one session of imaging takes up 4% of the camera's lifetime. If I used the Pentax for Solar System imaging it would have been dead over a year ago. I can't put a dollar value on my camera, it is modified, and now that I'm retired I can't afford to buy a replacement for something I use for a hobby.

I use my K110D for Deep Space objects where 15-50 images per night are typical. PhotoMe says it has 7800 shutter clicks, it should give me many more years of reliable service!

[falconeye]

You have an unusual method of putting a value on wear and tear. [...] That comes to an average of 6000 images per session.

I think we don't differ here. I talked about 100 activations, you talked about 6000 activations (0r 1/17 of a lifetime).

And stacking 6000 10 MP images would mean some wear on the hard disk as well ...

So, doing this stuff with a web cam is a good idea. Or, one of those new DSLR video modes could come quite handy (when you would ever decide to replace your K110D ).