I also use an add on focuser.
1) I center the add on focuser (I use a PDF focuser) in the center of its range.
2) I focus pretty well with the native SCT focuser knob. In doing this I make the final move of the mirror "up" (i.e. I turn the knob so the last motion I make is lifting the focuser). That is because if you make the last move "down" the mirror may settle a little more a bit later.
3) I then do final fine focusing using the add on motorized focuser.
I use FocusMax (a free program) to control the focuser. It is well supported and superb. For planetary imaging I tell FocusMax to make small moves (a few ticks" in then out until I am satisfied. For Deep Sky imaging let FocusMax do the focusing automatically. On a star it is better than you can be at determining the best focus point.
Drew S.
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--- In C14_EdgeHD@..., lmichel@... wrote:
--- In C14@y..., wonglijie@y... wrote:
dean c14 guys ..
when you all focus, do you all realise that the image will move
sometimes?
how do you all correct it?
thanks
This is caused by the mirror actually shifting while it moves on the
focus rack. It's corrected by any of the several after market
focusers available. See jimsmobile.com for a start....
