Warning about autofocus


#1

i know this has been queried before, but just for clarification…im using the latest beta and i guess i expected it to be resolved, i know this doesn’t happen in the earlier 2.5.0.23 ver, auto focus runs very well.

but im getting the focus warning again…when i know that the focuser is returning a good result, based upon absolute position…
anyone got any ideas why this is so…im ignoring it at the moment but it is a mild frustration.

Ray


#2

I get it too. I don’t know why… it is annoying, but it doesn’t stop anything from functioning.


#3

I’m not sure what this means. Resolved by you or by SGPro?

If you get this warning… and it is just a warning… it means your trip back to the calculated focus position yielded an HFR that was not within 10% of the expected HFR. If you are OK with this, then I would suggest ignoring it. It is meant to signify that your rig may have backlash for which you are not compensating or that you could have some other sort of issue like mechanical binding or slippage when the focuser is in certain positions (with respect to gravity).


#4

I don’t have any binding and I get this message. I’ve never had issues with SGP focusing; other than this prompt. Why was it added?


#5

For the reasons indicated above. If too many people receive this erroneously, we can bump the tolerance, but I think it’s a useful measure (keep in mind it’s been around for well over a year now… this is not something new to AF).


#6

I was just noticing with build 2.5.2.4 that the warning I got does not seem to take that 10% into account. I got the warning and it said my HFR was 1.31 and the expected HFR was also 1.31.

Chris


#7

I would be very interested to see logs showing this behavior. The example from the OP achieved an HFR of 2.02 when 1.85 or lower was expected. I also have tests we run prior to release of any version of SGPro and in these tests, no warning is issued so I’d be curious what circumstances lead to it.


#8

Hi Ken, thanks for the reply, i assumed that it had been a bug at sometime, thats what i meant by resolved!
for me the point was that it never happened in the previous version noted above…i have not changed anything in my mechanical set up since loading the latest beta today, hence my query…

i do know that my focus is good despite the warning and im happy to ignore it but it is clearly worth the discussion, i have just completed a run of 7 hours, on the rarest of clear nights, i cannot complain can i?
this software is without doubt superb :slight_smile:
after chatting to my friend, he suggested that it may be related to the seeing conditions, i dont fully accept that but it is a fact that my seeing earlier was terrible, i wish i had tried or been here when it had improved but bed called whilst it ran…

just seen your request for the focus packs…uploading now.it will take a while so ill comlete it later.
regards Ray


#9

Here’s the log.That particular focus run ended at 8:32:56. It says the validation frame HFR was 1.31 and the expected was 1.31.

sg_logfile_20161010200919.txt (415.9 KB)


#10

dropbox link to focus packs Re: warning about autofocus.

Ray


#11

I think this is worth keeping even though with my system it rarely has any significance and is more likely caused by seeing fluctuations than anything. It seldom shows up. It might be nice to have it a bit more customizable such as turn it on or off and/or adjust the percentage that triggers it. It can be useful to know if something is badly wrong with the focus.


#12

I think it is a very useful feature although I have seen the same thing cmassa has seen. It is easy to ignore or dismiss, but when it does pop up, I’ll take a closer look at the graph to make sure it looks good. Even with a perfect graph and perfect focus, the message is still likely to pop up occasionally if seeing is marginal, causing the validation frame to have a slightly higher HFR than expected. As long as it only happens occasionally, it’s not a problem. If it happens every focus run, it is an indication to me that backlash or some other issue is preventing good focus.

Tim


#13

@libraryman2

We will go ahead bump the warning to 15% above the low HFR encountered.

Also, as a side note, you would probably be better off running AF with a binning of 2x2. You will still have adequate resolution for the AF routines, you can make your AF exposures shorter and you get half the download time.


#14

This happens when your low HFR, in this case is ~1.179. The maximum acceptable calculated final HFR for the validation frame is then 1.31. The dialog, in this case, is confusing because of rounding issues. The validation frame HFR probably had an HFR = 1.3156 and the max tolerance is 1.31. This will cause the warning dialog to appear.

To prevent this, I have rounded the HFR metrics prior to the comparison.


#15

Hi Ken thank you for the reply, can I just ask you to check if when you looked at the af logs, that you read the logs that I actually sent…
The logs pertaining to the hfr 131 issue.

sg_logfile_20161010200919.txt (415.9 KB) were not sent by me but by another responder.
Ray


#16

just ignore this last message, I may have misinterpreted the email from you.

Ray


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