Quote:
Originally Posted by AlexN
Greg, Yeah I mentioned fast refractors earlier in the thread.. My TMB 80mm F/6 seems stable at prime, however insert the reducer and run it at F/4.8 and all of a sudden I get shift... I run a JMI motorfocus through a FCUSB controller for auto focus, and while its not temp compensating, I can script in focus confirmation through CCDAP.. There is no way I'd sit there watching a thermometer all night refocusing manually every hour or two...
The reason the faster scopes are more sensitive to thermal expansion is that the faster the optics, the slimmer the Critical Focus Zone.. at F/6 mine is 79 microns where as at F/4.8 its 50.6 microns... I'd hate to be trying to manually focus an F/2 camera lens with a CFZ of just 8 microns...
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Interesting. So that's why.
CCDAP which program is that? I have to get my temp compensating robofocus callibrated. You have a routine to go through to set it up.
Greg.