PIPP - stabilise an AOI on 320x240 AVI?

[furrysocks2]

I have a dob that doesn't track so the moon drifts across the field of view.

By carefully selecting an AOI in 640x480 videos, I can crop the video to an area that is present throughout. But 320x240 doesn't seem to work - the output is cropped to the correct size, but the image drifts.

The only reason I want to try this is because the camera I use gives me 125 fps, and can be made to do 187 fps.

Has anyone else come across a limitation such as this?