Could this be a viable option to the auto focus routine

Hi SGPro Team,

I notice when I have my Esprit connected the auto focusing works flawlessly

When I am using my RC8 then the issue starts.
The auto focus although does a pretty good job is sometimes touch and go, an when evaluating the image, I find the smaller stars are out of focus, so I need to stop the sequence and do a visual focus by taking an image and making some small focus adjustments until I am happy with the results. Then continue the sequence run.

So I did some test and found the following.
If I slew to star-field that had very small stars the auto focus seemed worked basically flawlessly.

However, when I slewed not far from that field, that had Larger and medium stars as well as smaller ones. I would end up with the same problem slightly out of focus on the small stars.

Now, I know we have the option of changing the ‘Min star Size’ to get around some of these issues.

So would the following be a viable addition (option) and improvement to auto focusing.
Been able to nominate what size of stars that would be used for auto focusing.
For instance I would select min size 3 pixels to 7 pixels, this would ignore all other stars above and below the set values.

Of course I realize this would limit the amount of stars in the field for focusing but may improve the overall performance for the RC8 and other similar type telescopes.

I have wondered about the same thing.

I observe from the logs that the maximum star size is always 20x the settable minimum star size. What I noticed was that a group of tight stars would be recognized as a single star with a artificially large HFR. If there are only a few of these when at the same time a large number of stars are recognized then the impact my be negligible. I suspect it would be worse if say only 24 or so stars were selected. I don’t know if this would be a problem for the RC - presumably the smaller field would yield fewer stars to work with.

I am not sure if this relates to RobinBrown’s observation and request or if it is a separate case for setability for both maximum and minimum star size. I get that too many parameter choices that need to be set can make an application more challenging to configure and use. But that’s what default settings are good for.

Jim Thommes

We’re working on some auto focus changes. We’ll take this into consideration.

Thank you,

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