Issue with FLATS generation

[stbkaiser]

Hi Robin
I am using your CAPTURE FLATS tool to create flats for my imaging.
When I try to use the AUTO ADJUST GAIN/EXPOSURE it always comes back with AUTO EXPOSE FAILED
but the histogram status shows OK.
I am using a LED tracing panel with adjustable brightness, RAW 16 color space,
with a ASI2400MC PRO camera on a Astrotech AT92 triplet refractor, with a Optolong L-pro filter.
Does the AUTO sw not like to work with a OSC camera?
Is there a setting I am missing for AUTO to work?
Attached is a screen shot showing the result of trying AUTO mode.
Thanks for help with this.
Steve

[kaymann]

The reason I do not use auto in Flats is it will change the gain to get things right. I have always been told to ensure lights gain and flats gain were the same and I have specific gain requirements in my lights... Something to think about when creating flats. Also the manual method is pretty easy to accomplish in SC. YMMV.

[Gfischer]

I agree with post2 , I keep my gain at 102 which is my hgc switch point. I have read that you should make sure your flats match the lights as far as conversion modes. I still use the sc flat tool just not the auto exposure/gain button. I noticed even with a gain of 0 your histogram is really spread out. I use a led trace panel as well but have several layers of paper over led panel to bring brightness down.

[stbkaiser]

HI
from digging deeper into Robins help -user notes
Capturing and Using Flat Frames
Introduction to Flat Frames

"Setup Camera Settings
Ensure that the camera is set to the correct settings at this stage. If you intend to image at 1600x1200, bin 1, RAW12 then set the camera to those settings before capturing flat frames. There is no need to use the same exposure or gain for flat frames (in fact this would not normally work). Since flat frames should have as little noise as possible, it is usually a good idea to set a low gain value. No need to worry about camera Temperature"

Looking further in his notes, for a Color camera, it seems it is best to tweak the exposure and light panel brightness to get the WHITE channel of the histogram in the 45-60% region.

So for my color camera, I will skip the AUTO mode and do manual adjustments to exposure and light panel brightness with low gain value.
Thanks for responses.\
Take care
Steve

[admin]

Hi folks,

the 'auto' approach tries to keep the histogram above about 85% and below about 20% clear to avoid problems with over/under exposure. My first guess based on the screenshot above is that the red channel being so much lower than the other two is the most likely cause of the problem - tha auto exposure is failing to find an exposure/gain that meets its requirements, and it is set up to be fairly picky (better to fail from time to time in situations that could perhaps succeed than to succeed wrongly when the exposure isn't correct and generate flats that don't work properly).

I guess the colour balance is going to be down to the light source for the flats being a fairly blue-white colour perhaps? It might be worth trying with a more neutral white just as a test to see if that makes it work, or maybe just cheating by increasing the White Balance Red amount (I don't think the flat creation code will try to reset that).

cheers,

Robin

[stbkaiser]

HI Robin
To get technical on this .
From the little document sheet provided with the Light panel , it looks like the Led Color is in the range of 10000-12000K.
The Auto mode is not really a big issue.
Out of curiosity I need to experiment with how the Histogram reacts when I don't use any filter and maybe the L-extreme .
(as noted I had a L-pro filter in the imaging train.)
I would expect a shift in the histogram.
So much fun paying with your software!
Thanks for your great support and continued improvements.
Take care
Steve