Focusing during an Image Session

[Peter_Myers]

Greetings to the BYEOS forum....

 

I have a simple question to ask the collective group...

During an imaging session I understand that we can pause the image capture at the end of the current image download.

My question...is that suppose I want to capture 25 images for a single night @ 5 minute exposures.  During the image capture session the temperature drops a couple to several degrees...is it possible to refocus the scope during the exposure plan to compensate for the temperature drop.

 

Looking forward to responses...

[admin]

Sure, but it does involve a few manual steps.

1. stop the session
2. goto Frame&Focus
3. If you have a bright star in your current field of view use it to focus.
4. If you do not have a bright star in your field of view slew to a star near by
5. Focus as you normally would, as you did before the imaging session
6. Slew back to your target (if you had to slew to a star in step #4)
7. Continue your session.

Regards,

[admin]

Also, if your focuser is motorized is if it has temperature compensation I would suggest you learn how it works with your focuser and let it do all the heavy lifting as the temperature drops overnight.

[astroman133]

I agree that temperature comp in the focuser can help to mitigate the issue of focus shift due to nighttime temperature changes.

If slewing away from your target to a bright star for focus adjustment is a problem, then you might try using short snap images for focus adjustment. It is a bit slower than using LiveView but you should be able to make the adjustments without moving the scope or even pausing autoguiding. This saves the need for slewing precisely back to your imaging target.

[Peter_Myers]

Guylain,   Astroman

 

Much appreciate your response to my question.

 

Peter