Autofocus trigger based on HFR % change

This would allow refocusing when it’s really needed rather than guessing how much temperature change or elapsed time will cause the need for a refocus. It would seem fairly easy to implement since SGP already calculates HFR.

-Dan

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I requested this a couple years back and it was turned down. Good luck.

I read the previous thread on this topic. @Jarod, your point is that HFR cannot be relied upon in all situuations. While true, that is also true of using a temperature trigger or time trigger. Depending on where you’re getting your temperature reading, the air temperature can change quickly while the equipment temperature can lag far behind. A time trigger is only a guess, and can have you focusing when it’s not needed. Any trigger method is not foolproof.

It would seem like the best approach is to give users the option to use the trigger that works best for their situation and their gear. Adding HFR as a trigger would be fairly simple to implement and would allow users another good option for triggering focus.

It would, of course, be good to offer a little more customization to make this measurement more robust and less subject to random variations in HFR. For example, you could allow the use to set a % change, and a number of images/measurements for that change to have occured before triggering an AF. This is similar to your dither settling where the user can say they want the guiding to settle to less than 1 pixel for 5 seconds, for example. In this case I might say I want to AF if the HFR increases by >10% for 3 exposures.

-Dan

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