Autofocus & integration focus differ


I am using a My Focuser Pro 2 focuser, the problem I am experiencing is the focus routine works just fine, it will find the lowest hfr and continue to chart a good “V” then return to the position for the lowest hfr, take an image which is generally around 1.6 - 1.7 and shut down.
Once sgp integrates the first image after autofocus, if I select “Image Statistics” icon the hfr is always higher, in the order of 2.5 - 3.00.
The focuser position is in the same step position as when autofocusing, but with a higher hfr.

Any help or suggestions would be appreciated.


Lots of factors can contribute to this. You should really only be comparing HFRs for “like” frames. So similar binnning, exposure time, filter and gain.

Longer exposures will cause bigger stars, increasing HFR. Binning will change the sensitivity creating larger stars for the same exposure time (same with gain) and filters will block more light causing lower HFRs for more restrictive filters when all other things remain the same.



Thanks for the heads up Jared .