Bias offset setting location in Sharp Cap Pro

[RichNH]

Hi, I'm pretty new at all this AP stuff and I'm really confused right now as to how I can set the bias offset value in Sharp Cap Pro. I'm talking about adding a standard value to each pixel's ADU value so that there aren't any negative values being cut off and marked as zero when the ADU value is reported. I've looked through all the settings that Sharp Cap Pro shows me when connected to my ASI533MC camera. I would have thought that the value would be in either the Camera Controls frame or the Preprocessing frame but I'm just not seeing it. I tried playing with the Camera Controls > Exposure/Gain Shift but using that modifies both the exposure and the gain settings, which I don't want to do.

Am I looking in the wrong place?

Clear skies!

[admin]

Hi,

for historical reasons, that control is called 'Brightness' on ZWO cameras, and is located in the 'Image Controls' section on the right, rather than the camera controls section. Unfortunately too many people are now used to the name/placement to make changing it easy, sorry.

cheers,

Robin

[RichNH]

Fine by me where it is. Thanks, now I can play with it a bit. The reason I wanted to know was because of this image of M33 I put together last week. There were a number of speculations on Cloudy Nights that my coloration problems were caused in part because my flat master wasn't generated to populate pixels to the edges (due to the negative ADU measurements being cut off) Again, that was speculation about would could have been part of the problem.

Edit: However I now see when I checked that control, it was set at 55. So I guess it wasn't 0 as originally thought. Perhaps a higher value is called for with my camera.

[admin]

Hi,

I would suggest taking a look at the master flat file itself - see how much darker it is in the corners than the center and also what settings for the brightness and white balance controls were used to create it (if saved by SharpCap there will be a CaptureSettings.txt file next to the actual image file). Similarly for the master dark (in terms of controls). Mismatches between the light and dark frame settings, or between the flat and dark flat (or bias) can cause this sort of issue with over/under correction in the areas with the strongest correction. There is a bit in the documentation about getting good flat frame correction : https://docs.sharpcap.co.uk/4.1/#Gettin ... Correction

Hope this helps,

Robin