Temperature triggered autofocus routine

[darknrg]

I've been trying to find this feature within the program and also in the forum, but I only found a post where it was mentioned that it was not available yet.
Alas, my DSO imaging scope (takahashi fsq106) is extremely sensitive to temperature changes and it is critical for me to be able to launch autofocus even if the temperature changes by 1 degree. The alternative to make sure to have perfect focus during the whole session would be to autofocus every few frames. But that would be such a waste of time and, furthermore, would not ensure the same result.

So, have I missed it somehow and it's already somewhere within the program, or isn't it and then would love to know if it is in the to-do list for the hopefully near future.

Thanks
Luca

[Jean-Francois]

Hello Luca,

Which focuser do you have ?

Some focuser allows to set a focus position depending on the temperature.
The difficulty is to have a refocus only between two images.

SharpCap does not have this capability directly ... but you can write a script that perform a check of the temperature and then change the focuser position (only a few steps) depending on the delta temperature.


Regards,
Jean-Francois

[darknrg]

Thank you very much Jean-F.

For now, I don't have a focuser on my Takahashi, since I've been using very little. But now I decided I need one because Takahashi's focus is very sensitive to temperature changes. For the time, I'm leaning towards a PLL Sesto Senso focuser (I'm Italian so I'll give the guys at Prima Luce a hand ), but I don't know if it has the feature you are talking about. I'll investigate

Thanks for the suggestion, but that will need some testing. I was wondering if, instead of just instructing the focuser to move a few steps in or out (that's why I mentioned testing: I still don't know how the temperature affects the focus, whether it's in or out and also how much), I could write the instruction to simply redo an autofocus run if the temperature changes of x degrees plus or minus (although it's usually minus).

I would hate to have to re-start the learning curve to use NINA!

[admin]

Hi,

as Jean-Francois says, some ASCOM focuser drivers have a temperature compensation function - this would need to be configured in the ASCOM driver itself (after some sort of measurement process to work out how far to move per C change), then can be enabled from SharpCap. I've never used this personally, but seen the feature on some drivers.

The other approach you could take is to use the SharpCap advanced sequence editor - there is a step that sets up a task to be run when the focuser temperature changes - typically you would configure this to run a refocus, and the way the sequence works will ensure that is it run between still frame captures rather than during a frame. Look at the 'Run a periodic task named <XXX> when focuser temperature changes by <YYY>' block.

cheers,

Robin

[darknrg]

Hi,

as Jean-Francois says, some ASCOM focuser drivers have a temperature compensation function - this would need to be configured in the ASCOM driver itself (after some sort of measurement process to work out how far to move per C change), then can be enabled from SharpCap. I've never used this personally, but seen the feature on some drivers.

The other approach you could take is to use the SharpCap advanced sequence editor - there is a step that sets up a task to be run when the focuser temperature changes - typically you would configure this to run a refocus, and the way the sequence works will ensure that is it run between still frame captures rather than during a frame. Look at the 'Run a periodic task named <XXX> when focuser temperature changes by <YYY>' block.

cheers,

Robin

Thank you very much for the tip Robin. I will try it and report back. I hope I'll be able to set it up with your clear instructions.

Cheers
Luca