How to use focus assist with a focuser that has a motorized focuser with a handwheel only?

[pastorgalactico]

Hello;

Won't that be too many stars?
I'm using the Uranus C with an effective focal length of 1292mm, and often that many stars won't be visible.
On the left side, what settings should I use for the configuration, considering I'm using a 16" f/3.19 lens with the Uranus C and a 2000ms exposure?
Regards.

[admin]

Hi,

ah, OK, with the small field of view it will be hard to get that many stars. You can try increasing gain and/or exposure to bring more stars up to a brightness that can be measured, but added gain can increase noise (and therefore variability in the measurements) while extra exposure slows things down - longer to take each measurement.

I think the settings I would recommend for deep sky focus with Multi Star FWHM are something like :

Averaging:

Average over 1 frame
Show average score

Star Detection:

Suppress hot pixels on
Use display stretch off (in up to date versions of SharpCap it is not needed for 12/14/16 bit images)
Max brightness 90-90%
Noise reduction 0.5 to 1
Sensitivity 75+

To try to get more stars, turn up sensitivity and/or turn down noise reduction, but check that the boxes are drawn around real stars, not just noisy bright bits of the image, particularly if you push sensitivity very high or noise reduction very low.

If you still can't reliably get enough stars due to the small FOV, try the single star FWHM measurement on a single bright star, or you could consider a bahtinov mask.

cheers,

Robin