How can Ekos be used to determine the ADU value from a preview image?

I am using the ASI1600MM-c for imaging, and following this thread on CN: www.cloudynights.com/topic/559771-asi160...cheat-sheet-no-math/

At unity is says to expose until ADU 850. When the statistics for the Fit are used is it the mean value to use?

Any help is appreciated.

Mean would be representative of ADU but really you should study the full histogram of each capture and filter combination to be sure.

I found that thread helpful as I don't seem to be able to understand the histogram in the kstars fits viewer. Every image starts with it scrunched to the left, and it does not seem to take to adjustments very well for me. Is there a video or tutorial on how to use it? I have used the one in astrotoaster, as an example, and seem to get around that one okay. My images seem to be okay as they stack nicely and give good detail. I think now that I have over-exposed some stuff that I may go back to and play with more.

With the histogram open I manual type in and reduce the Max value number until I see the histogram appear. If the Max is 65k I would type in 15k then 5k and so on until the histogram appears.

The histogram tool reports 16-bit ADU, which is inferred from the max value.

The ASI1600 is a 120bit camera. According to the link at unit gain 139, offset 21, I am to expose until I have 850 ADU.

The fits from last night report a mean of 272.

Being in a LP zone, already shooting at a 120s exposure, I have trouble thinking I should be shooting longer to get to 850 as the mean value.

However, is that what this means, or does this histogram mean value mean something else?

For Flat frames ADU is very important and Ekos has a great feature for automatic ADU analysis.

Light frames is more about SNR. The following is a recent YT video to help visualise SNR.



Aiming for a Mean 850 ADU sounds a little random. Maybe it was specific to a particular object. Best advice I can offer is to visualise the histogram and maximise the SNR.

Im pretty sure that the 12-bit ASI1600 is converted to 16-bit in the fits conversion process.

I'm imaging tonight and tomorrow so will try and add some reference to my comments.