|
sure is a problem Stuart - a real pain. In the region of f4, there is next to no tolerance. CF helps, but as you point out, the Al stuff does it's own thing anyway and you still need to refocus at the slightest temp change.
FWIW, I need to refocus at about every 0.2 degrees with my current steel tube f4 - I have just bought a CF scope, but back of the envelope calcs show that I will still need to refocus about every 0.5 degrees.
Do ASA provide any temp sensing for their focuser? - would have thought that it should be relatively straightforward to get a high end focuser like that to track with changing temps, which is what you will need if the focus is drifting within subs. If they don't, there are a few stepper focuser drive systems out there that incorporate temp sensors - doubt there is anything magic about ASA stepper motors, so it should be fairly straightforward to use an alternative interface box and get one that can operate with your chosen software.
The other thing that is useful is a low read noise camera, which allows short subs - only a consideration if you are in the market for a camera though.
Could an aircon in the obs be an approach to get your system ready for imaging before midnight?
Last edited by Shiraz; 21-01-2014 at 03:30 PM.
|