ZWO ASI120MM exposure and gain control

[Jay L]

I keep having issues with star SNR and the subject guide camera. Often times I have a non-zero gain and the star SNR is around 6 to 8 with frequent "Saturated" showing up next to it. If I drop the gain to 0, the SNR jumps up to between 20 to 30 and is not saturated. There are other times when I can't make a perfectly good guide star fall in the acceptable range. What's going on here? Am I not using the auto-exposure parameters properly? Seems like this camera worked better in earlier versions of PHD2. Are there plans to give the user direct control over the exposure and gain?

Thanks for your help

Jay

[bw_msgboard]

Some suggestions:
1. Don't use "auto-exposure" - choose an exposure time of 1-2 seconds, not
something in the sub-second range.
2. Make sure the camera is well-focused
3. Use a dark library or a bad-pixel map
4. Let PHD2 choose the star via auto-select (alt-s while looping)
5. If you think PHD2 is choosing a star that's too faint, adjust the gamma
slider on the main display so you can really see what's in the fov
6. Use the star-profile view to look at the properties of the selected star

If the above doesn't work, save a FITS image of the guide cam image - NOT a
screen shot - and post it on the forum here.

I recently connected my ZWO as a guide cam with PHD2 just as a test - no
problems at all, lots of good stars, and no need to mess with the gain
setting.

Good luck,
Bruce

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[bw_msgboard]

Don’t know why the formatting got hosed in my original response – here’s another try

 

1. Don't use "auto-exposure" - choose an exposure time of 1-2 seconds, not something in the sub-second range.

2. Make sure the camera is well-focused

3. Use a dark library or a bad-pixel map

4. Let PHD2 choose the star via auto-select (alt-s while looping)

5. If you think PHD2 is choosing a star that's too faint, adjust the gamma slider on the main display so you can really see what's in the fov

6. Use the star-profile view to look at the properties of the selected star.