Sorry for bumping this thread, but it's just was I looking for. Paul's tips are very useful, I agree. However, I'm trying to setup this kind of cycling shooting but I want to dither in every loop (this kind of imaging, by the way, can avoid wasting too much time for dithering). Is this possible? How can I dither between loops? If this is not possible natively, can I run a particular script in every loop? The idea is to run a python script to perform send a manual dither to phd2. I've been tinkering for a while but cannot find the way.