Quote Originally Posted by TRAPPIST View Post
- I had not switched off the TCFS focuser since weeks and I dont remember from where is coming the focus position in FocusMAx after a restart of the focuser. Sorry I dont remember. The value in memory of the TCFS ? I cannot find an "absolute" reference position defined in FocusMax (or maybe I did it during the first startup procedure ?)
The value is stored in the .ini file you're using that is in the FocusMax/Data Files folder (Windows XP) or User/My Documents/FocusMax folder (Windows 7) - the value is called "PreviousFocus"

- We operate with the focuser always on (no daily restart). At the end of the night the CCD is disconnected. The Focuser stays on focus postion of last filter used. When CCD is powered up, the wheels rotate and go to one given filter (always the same). But the focuser is still in FocusMax on the focus position of previous filter. Next focus offset will then be wrong ?
Yes, it will be wrong. This still happens to me, too. I thought Bob had fixed this in one of the version 5 hotfixes, but it doesn't work right for me now in version 6 either. I typically take a "default filter" exposure at the end of the night so that the focuser is repositioned to the default focus position and the filter itself is moved to the default filter position. It could be, I think, scripted as part of the Terminate() process when ACP shuts down.

The FilterInfo.txt has been done since a long time and out system is working but I have to check FocusMax is starting with the right focus value.
Maybe I need to reinitialise the TCFS focuser ? (the change the offset values in the filteroffset file). THey were close to 0 for one set of filters.
The offsets should still be okay. But the zero point might migrate depending on the ambient temperature and its effect on the expansion or contraction of the OTA. Even if the focus is wrong at the beginning of the night, the first autofocus should find the correct focus right away.

- last : I noticed acquire star is looking for star sometimes very far (2 deg), then finds a lot of candidate for focus (mag 11-12) about 1000 stars and then it looks to me this is slowing down FocusMax. Is there a way to say to FocusMax to only look to a smaller field ?
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You can adjust this value by changing some program constants in AcquireSupport, if you are NOT using FocusMax's AcquireStar. In AcquireSupport.wsc, search for the statement that says:

"The PinPoint "image" is 30 by 30 pix"

The next little bit of code establishes the FOV window for selecting a focus star. It's set for 5x5 degrees by having PL.ArcsecPerPixelHoriz = 600 and PL.ArcsecPerPixelVert = 600. If you change 600 in both places to 120, you'd search a 1x1 degree field. If you change 600 to 60 it would search a half-by-half degree field. Set your own threshold.