RGB balance with QHY715C camera

[Jean-Francois]

Hello,

I received yesterday a new QHY-715C camera.
Something is not working with the RGB balance ... or I did not understand.

It should be possible to change the colour "scaling" for the R, G and B channel independently .. is that correct ?
The R, G and B values can be changed between 8 (not 0) and 255.
I do for the R and G and it happens something. But when I change the B value absolutely nothing happens.
I tested it from 8 to 255 ... nothing changed on the image view.

I tested with the 4.1.11351. I will now test on a different computer with the last version (4.1.11433).

For the scaling ... what is the intermediate value ? ... what do nothing. I would say if the maximum is 255, then 128 could be the middle.
Means if all the RGB values are set to 128, then each pixel is "scaled" by 128/128 = 1 ... so nothing changed.
If the value is smaller than 128, then the pixel value is reduced by the factor value/128.
If the value is larger than 128, then the pixel is increased by the factor value/128.
The first small problem I see is ... it is only possible the increase by a factor of around 2 ... means 255/128.

Or it is completely different ... the G value is the basis and the other give the value.

When I started the camera the first time ... all the values were 64 (not 128) ... so it is less comprehensible.

Regards,
Jean-Francois

[admin]

Hi Jean-Francois,

sadly this sounds like an SDK issue. However, it looks like there is a new version of the SDK available (newer than the version in SharpCap - see https://www.qhyccd.com/html/prepub/log_ ... !log_en.md). It would certainly be worth trying copying the qhyccd.dll from that SDK over the SharpCap one to see if it improves things. I will try to bring the new SDK into SharpCap soon, but will have to do some testing of it first.

In theory, all three colour sliders should work - SharpCap treats them all in the same way. The minimum and maximum values come from the SDK, but there is no way to ask for the 'default' value, so I have no idea what the neutral values would be for a particular camera (I know that the ranges available and the neutral values vary from model to model).

cheers,

Robin

[admin]

Hi Jean-Francois,

I haven't actually had a 715 camera here yet to test, so can't comment from experience. It is a smaller pixel (1.44 vs 2.4 micron), so that would account for nearly a factor of 3 reduction in sensitivity due to the smaller pixel area.

Good to hear that the occultation went to plan - do you have any science or images to share?

cheers,

Robin

[admin]

Discussions of the occultation of Betelgeuse by Leona split off to this topic : viewtopic.php?t=7268

cheers,

Robin

[Jean-Francois]

Hello,

To close the topic ... I received my camera back few days ago.
It was a problem with the camera firmware.

Now I can do the white balance, here an example on the view from my window:

QHY715C_colour_problem_solved.jpg (58.71 KiB) Viewed 8390 times

Upper image is before the white balance, lower image is after changing R and B levels.

Regards,
Jean-Francois