Focus Assistant Extraneous Symbols

[larryh]

Hi,
I am using an ASI294MC pro with motorized Moonlite focuser and the focus assistant to find my optimal focus. I just started using Sharpcap 4.0 (Windows 10 64-bit), and am on version 8047.0. I find that each time I change focus position, I get an extraneous symbol (green or red triangle) in between the previous focus position and the new focus position. This did not occur in 3.2. The following document shows three consecutive focus positions.

focus bug1.docx

(500.28 KiB) Downloaded 45 times

Here is the log, multi-star FWHM focusing around 21:53.

Log_2021-08-05T20_41_40-6260.log

(194.57 KiB) Downloaded 36 times

Thanks!
-Larry

[admin]

Hi Larry,

thanks for the report - I think that this is related to changes I made to support still camera mode.

In 3.2, the new point does not appear on the graph until the second frame arrives with the focuser on the same position - this basically filters out any measurements that come in from frames taken while the focuser is moving. On the other hand, when you are using a camera in still camera mode and only taking frames after the movement is complete, it's not acceptable to have the first frame you take not produce a data point on the graph.

If focusing is still working in spite of the extra points then please ignore them. If they are causing problems with your focus procedure then let me know and I will try to prioritise a fix.

cheers,

Robin

[larryh]

Hey Robin,
I see what you're saying about the still frame issue. So the extra symbols are actually measurements from a frame that comes in while the focuser is moving. The extra symbols don't prevent me from focusing, but they do make it more difficult because the graph becomes filled with symbols as I search for my focus point and it can be hard to see which ones were from a settled focus position. Since the extra ones are based on a single frame while the focuser is moving, they are probably not a good representative FWHM measurement.
I can't say that you should prioritize a fix because I'm sure you've got bigger fish to fry. Maybe something simple like a user selectable checkbox for "old way" (wait until second frame at same position) vs. "new way" would be easy to implement. In the meantime, I guess if I were to use somewhat longer exposures, I could at least reduce the probability of getting an extra symbol. I will experiment with that.
Anyway, I very much appreciate your feedback. Also, thanks for making Sharpcap such great software!
-Larry

[admin]

Hi Larry,

it's actually not quite what I thought - I went looking for the code that dealt with the extra items in 3.2 and it is still there in 4.0 if the camera is in live mode - something else going on. Will add it to the list of things to investigate.

cheers,

Robin