How Meticulous Should I be with Flats Histogram?

[fatboy1271]

I finally got an LED Light Panel and it is Awesome!!! It's intended use if for tracing "art:" however, it is fantastic for Flats.

This morning I shot my Flats from last night's session and went through all 100 of them. Then I ended up reshooting about 30 more because the RGB graph moved slightly in the Histogram of BYEOS.

I drew yellow lines to make is easier to see the movement. Garbage in equals garbage out, right? I know PixInsight is incredibly powerful, so my question is do I need to be this meticulous or will PI take care of everything when I create my Master Flat?

Good and Bad Flat Frame.PNG (5.26 KiB) Viewed 1596 times

fat

[UlteriorModem]

Pixinsight will calculate the averages and produce a workable flat. That little bit of movement is certainly not worth obsessing over.

Two things to look out for when using a flat panel. First make sure the exposures are not too short due to too much light out of the panel. Try to get the histogram left of center. You may have to add a t shirt or some white paper to dim it down.

In the end the proof is in the pudding. Look at your master flat and see if it reflects the defects in your setup. A good way to do this is to open one of your image files, then open the master flat and drag it over the image file and see if the defects 'line up'. You may have to stretch them some to see it clearly.

[Stuart]

I wouldn't use a histogram at all. Use the average ADU. For a 16 bit scale shoot for an ADU between 25,000 and 35,000

[fatboy1271]

I wouldn't use a histogram at all. Use the average ADU. For a 16 bit scale shoot for an ADU between 25,000 and 35,000

Thanks Stuart... How do I find the ADU?

[Stuart]

Sorry I was offline for awhile. Measure your average ADU of your flat with software. Some sequencing programs such as SGP will automatically do your flats for a particular ADU. The Backyard EOS line does not, as far as I know.
Usually, though, I measure it with the Statistics process in PIxinsight.

[fatboy1271]

Thanks Stuart! I figured PI could do it; I just didn't know what Process.