Question About Temperature Compensation (for autofocus)


#1

Hi, during several nights while testing SGP, I have written down the temperatura and focus position (after an autofocus run), but I’m not getting a linear curve (more of a zig-zag). I have an FSQ with Robofocus. Can you please suggest what’s happening? Maybe because this has to be done on the same night? Thanks for your help!

(Note: I haven’t had time to use the Temperature Compensation trainer because I need to run it for 5-7 hours to get 5ºC drop right now).

Miguel


#2

Yes, it absolutely has to be over the same night. Differences in seeing, transparency and humidity will all affect the HFR (and thus the focus position). In addition to this, if you have backlash in your motor, you will see some difference night to night. Because of this, most folks don’t try to mail down exact positions that achieve focus at any temperature. They just understand that “around this position is focus”, then let AF take care of the rest. After this, the only import aspect of recording ficus positions is understanding the differences between filters that achieve focus.


#3

I have an FSQ and it is linear. For me, I start the night around 2300 and end it around 2200. Rinse and repeat :).


#4

Thank you Ken for your reply. I imagined it probably had to be done in the same night. The next night I can spend 4-6 hours I will run the Temperature Compensation Trainer to find the steps/degree.

Thanks again.
Miguel


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