Since moving to a 10" RC scope I have noticed that there are far fewer stars for the autofocus routine to measure than I was used to with refractors. Often there is only 1-2 stars when the focuser is at the outer point of the V curve, and only 15 or so when in focus. This is confusing because there are many, many more stars in the FOV but they aren’t picked up by SGP.
The minimum star size has always confused me and I don’t get it. Right now I have it set to 12. But I’ve tried changing that to 2 and 20 but there is no change in how many stars SGP picks up for autofocus.
How can I tell SGP to choose more stars for autofocus calculation?
Something definitely out of whack with your autofocus. I run the autofocus routine for 2 years with my 12" RC and usually had hundreds of stars chosen by the routine.
Joel. I’m using a 10" RCT - I increase the exposure a little and do not go too far out, or as you say, the stars become too diffuse to be identified. I’ll dig out my AF settings.
Just thought I would weigh in since I have nearly the same exact setup.
I have witnessed the same behavior, not very many stars used for weighing Hfr. I see a few stars that look like they ‘should’ be used but aren’t. I also see nebula or small galaxys measured and added into the calculations.
I reduced minimum star size down to 4 and that helped some, however I do not see as many stars used as I did with the APO or Newt.
Why this is I do not have a clue. Maybe something to do with the as/pix ratio which is down in the .56 range. However it does find enough stars to get a reasonable curve. But there is room for improvement… as always
Thanks for the replies. It appears as though it makes some difference
where the scope is pointed and how many stars are in the field (and I also
suspect seeing conditions affect it too). Last night I was imaging in the
north east and I was seeing 15-20 stars for HFR calculation even at the
outer most focus point. Previously I was in the southeast and there were
fewer stars overall in the FOV, and I was only seeing 1-5 stars in the
outermost focus point. But what doesn’t make sense to me is that there are
many, many more stars in the FOV that could be used for the HFR and they
aren’t picked up. As stated in my first post, changing the min star size
didn’t seem to have any effect.
I’ll be collecting autofocus packs over the next few weeks (terrible
weather here).
