Quote:
Originally Posted by Startrek
Peter,
What flat panel are you using for your Flats ?
Does it have adjustable brightness levels ?
Are you stretching a white T shirt over the end of the OTA wth a rubber band ?
I use a Huion led dimmable light panel and usually set t lowest brightness or just slightly above.
Photo my little 6” newt in Sydney taking Flats with APT
I set my panel brightness to lowest , Open CCD Flats Aid , Open the Histigram set it to Local , set APT Flats Aid to say 21000 target ADU , press Run then watch the Histogram move around until it stops. If it stops say between 8500 and 35000 ADU value where it says “Range” and the first peak ( RGB ) is located off the left hand side just away from blackpoint , 2nd peak in the middle and 3rd peak no further than halfway along the Histogram then I check Flats exposure value. For no filter used Flat are usually 0.2 sec to 0.5 sec , with L Extreme filter they can be 5 sec to 10 sec long
If the Histogram is not in the correct range then I adjust the light panel brightness ever so slightly or drop the ADU target range to 21,000 or even 20,000 sometimes
The Histogram Range is the key
Hope the above helps
Martin
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Sorry to bother you again with yet more questions,
Got everything back up and running again, just got to test it all out when we get clear skies.
I have ben working on the Flats Aid in APT, It appears that adjusting the light level, ( in my case it is a dimmable light box ) it is like a fine tuning of the histogram, while changing the ADU vales is a more course adjustment, at least that is what i am finding.
Si i have sort of ended up with an ADU value of 22000 for the asi2600mc,
This puts the 3rd peak of the histogram about half way along.
I the images below, the first one is with an ADU vale of 22000 and the range comes back at 12338 - 31587, i think this is look ok.
The second image is with an ADU of 30000 and the range is 16494 - 41419 and the 3rd peak is a little over half way along, but i think this is way over exposed.
I use the astronomy.tools to work out the arc seconds per pixel which comes back very simular to what you have said, 0.73 or 0.74 using astronomy.tools site
I do get wildly different histogram results depending on what you select on the histogram, ,like Log, Auto St-L, Auto Str-R, Local ( the range results remain results unaffected of course)
So just interested to know if i am on the right track here, to me it looks good, but still learning about this.
Cheers,
Peter.