I find it difficult to perform my initial focus in SGP using a DSLR with a Bahtinov mask. I find myself launching BYEOS for an initial slew to a bright star, grab focus and then open SGP.
Any tricks I’m missing here using SGP frame and focus?
Thanks guys. I am trying the same procedure I use in BYE, using live view but the image isn’t sharp enough to resolve the focus spikes, that’s where I’m thinking I’m missing something. Not sure what the process would be to use image history…just take images while adjusting focus and watch the FWHM?
We have considered integrating Bahtinov Grabber into SGPro in the past. Of course the original author (the late Niels Noordhoek) created and distributed this software for free. If we ever integrate in this way, it will be part of SGLite so we can continue to propagate the software according to the author’s original intent.
I’m also looking forward to this feature.
Not all of us uses auto focusing and this makes me much easier to focus than using SGP and he grabber separately.
One thing I’ve seen with all these focusing methods is the need to get fairly close to focus before they work. This applies with or without a Bahtinov mask.
What I see in the image when I’m a long way away from focus is a collection of circles or doughnuts. I make a focus change and see what happens. If the circles get bigger I’ve gone the wrong way. If they get smaller I’m going the right way. I continue making focus adjustments until I’m close enough for auto focus to work.
I wonder if this could be automated:
Collect an image
Detect circles (the Circular Hough Transform maybe)
Get the average circle radius.
Move the focuser.
Collect an image
Detect circles and determine their radius
Use the change in circle radius and focuser movement to find an
approximate best focus.
Move there.
Do fine focus.
I’m not sure how practical this would be and there’s a lot of development and testing needed but it could be very useful, especially if it could be used to avoid the problem of spurious low HFR values with obstructed scopes.
Another vote here for an integrated Bahtinov Grabber (or similar, of course)
I’ve got two scopes, but not enough money for two autofocus…
Regards from Spain.