Recently i gather frames for M42 and during evening temperature was pretty high (as for winter) and drops to freezing during few hours. I set focus on stars near M42 and then star a session.
As temperature drops my rig demant an autofocus, so SGP starts (after 2*C drop)… but as you know M42 is very bright in trapezium area and SGP’s autofocus routine was confuse and finally focus point was very wrong. Focuser was set to previous position (which was also wrong one) and i lost most frames of session because they were out of focus.
I don’t trust temperature compensation
Is there a way to “set” focus point (mount will go there, SGP will run autofocus and then come back to object, center and restart session)? I know, that there is something like “focus marker” but it doesn’t work in automatic session.
I dont think there is any such feature, but it could be useful. I have also hit issues when trying to focus with a saturated star in the fov. Being able to point to and focus on a non saturated star field would be nice - or being able to set an upper limit on the star size to use when focusing (i.e. to filter out over saturated stars…)
Steve, you are right - setting the maximum brightness or size of a star to autofocus will help a lot.
This issue occur also on galaxy fields or bright one such as M31 (core as a star).
