Auto gain/exposure failing in Flats capture

[FEObs]

Sorry to post this question here, but dambed if I can find the "new post" button.

So here it is.

In SharpCap, I am using Phd2 for guiding. There appears to be no screen controls (other than a very mild gamma corrector) for the looping images.

I am using a QHY500ii200m camera on 130mm guidescope. Everything shows up fine but any exposure more than 1 second blows out the image as in overexposed. This affects ability to see onscreen the stars, selected guide star etc.

Does anyone know if there is any histogram setting or adjustments?

Thanks

[turfpit]

FEObs

dambed if I can find the "new post" button

Select a forum, for example Gallery, then click New Topic:

new-post.JPG (40.98 KiB) Viewed 4294 times

exposure more than 1 second blows out the image as in overexposed

Gain (and/or offset) too high perhaps?


Dave

[FEObs]

Thanks Dave
It makes sense so I will try gain/offset first night it stops raining!!!

Also, thanks for guidance on forums/new topic.
Much appreciated.

Jimmy

[FEObs]

Hi Robin
Did you ever get a chance to determine a solution to this issue?
Thanks

[Gfischer]

I use phd as well. There is a gain setting in phd2 for
My camera asi120mc

[FEObs]

Hi Robin
I spoke too soon in last post.
I went back into SharpCap and the auto exposure now works for my QHY camera.

Not certain if you fixed, a recent update fixed it or, because I dumped the QHY native driver in favour of the ASCOM driver.

FYI...fort future reference if there are similar issues reported, my QHY247C has been calibrated in RAW16 and RAW 8 sensor analysis. Using the native QHY driver, it would not allow SharpCap Capture/Flats/auto exposure. However recently I noticed the 247 was imaging full chip including overscan area which makes flats useless.
(overscan in software was turned off). QHY says it should not be in images but...it sure shows up on flats.

But, I found first that at 2x2 Bin, overscan did not appear. Then found switching to ascom camera driver (with or without bininng) produced proper 6024 x 4024 images and flats.

Thanks
Jimmy

[admin]

Hi,

the autoexposure needs an understanding of how gain affects image brightness to work. For most brands of camera that's easy - ZWO, Player One, SVBony and others use a gain value that is related to brightness via a decibel scale. Altair, ToupTek, Mallincam and others have a simple 'percentage of minimum gain' value, so minimum is 100, 200 is twice as bright and so on. QHY sadly just have numbers for gain with no meaning beyond the fact that higher numbers make the image brighter. So, to get the auto exposure with a QHY camera, you will need the sensor analysis data. If you do the analysis with the native driver then the native driver should enable auto exposure, if you do the analysis with the ASCOM driver then the ASCOM driver should enable the auto exposure.

The overscan area is another can of worms entirely - I don't have a QHY camera that has the overscan ability, so I cannot test this directly, but there is code already in SharpCap that asks the camera to disable the overscan when opening the camera (and has had that code since at least 2021). At least I think it's the right code to ask the camera to ignore the overscan area - the documentation is very terse and I cannot test...

Could you open the camera in SharpCap in the native driver (in whatever mode shows the overscan), then close it, then goto Help->Show Log in SharpCap and send me the whole content of the log please? That should record the attempt to turn off the overscan and whether it generated an error or not, as well as some other potentially useful info like the size of the overscan area. Maybe that log info will help me understand if/how I am doing something wrong with the overscan.

cheers,

Robin