I've just uploaded a new update for SharpCap 4.2 beta, which along with the usual array of bug fixes and tweaks has a new feature that should help set up autofocus settings for those using electronic focusers.
The guiding principles around autofocus in SharpCap have been to try to make it something that you can understand and observe its success or failure - this was something that I decided long ago (long before SharpCap had any autofocus) when using a brand new autofocus feature in another piece of astronomy software (I won't say which...).
In that software there was a brand new autofocus button, so I set up my ASCOM focuser and pressed the autofocus button. The software moved the focuser around a bit. It took some images. It moved the focuser more and took more images. It announced that it had found best focus. No, not even close... The problem was not that it failed - the problem was that I had no information on what it had been doing or why. No information on why it might have failed, so no guidance on what changes I might need to make to make it work.
That experience made me ensure that SharpCap shows graphs of focus measurements as focus scans are proceeding and makes the user work through a manual scanning process successfully at least once before the refocus option becomes available and so on. However, this approach isn't always appropriate, particularly for more experienced users who already know how autofocus should work in astronomy.
To try to give another approach to autofocus, I have now added a new 'Autofocus Settings' window to allow all the settings to be edited in one place. To make this adjustment easier, there is a 'Test' button which will attempt to perform an autofocus using the specified settings, allowing settings to be adjusted and refined easily.
The new tool is currently launched from the control area of the focus graph as shown
- Screenshot 2026-09-28 152146.png (14.81 KiB) Viewed 68 times
Pressing the button loads all the current focus settings for the focus tool you are using (for instance 'Multi Star FWHM'). What you will see is something like this...
- Screenshot 2026-09-28 152823.png (96.54 KiB) Viewed 68 times
The lower area contains three separate tabs which contain the various autofocus settings for the focus tool you are using (I tried putting these three blocks vertically with them all in view together, but it made the window too tall and also it felt over-busy).
The three sections are:
* Focus Scan Movement - this lets you control how many measurement points there will be during the focus scan and how far apart these will be (the number of focuser steps between measurements). Note that you now have free control over the distance between measurement points, rather than having to choose from a list of set values like 10,20,50,100, etc.
* At each Measurement point - in this section you control things like how many focus samples to take at each measurement point and (most relevant for solar system focusing) what constitutes a sample - is it 1 frame or 20?
* Focus Measurement - this section has all the adjustments for *how* the focus value is measured - star detection settings for star based tools or noise reduction/binning settings for solar system tools.
None of the changes you make here take immediate effect - the 'Close' button (which becomes 'Discard Changes' if you have changed something) will exit this window and throw away any changes that you have made.
If you use the 'Test' button then the changes you have made will temporarily be applied and a test autofocus run will be executed. This might succeed - hurrah! - or fail. In the event of a test failure, SharpCap now tries to give some information about why the autofocus attempt fails and what might be good things to try to correct the problem - like this...
- Screenshot 2026-09-28 154831.png (23.1 KiB) Viewed 68 times
If you have made changes that you are happy with (and test out OK) then pressing the 'Save Changes' will take all the changes that you have made in the Autofocus Settings Windows and apply them so that they will in future be used by the selected focus tool.
Obviously this is brand new, so I may need to tweak/adjust/improve things based on end-user feedback, so do let me know what you think!
cheers,
Robin