DSLR Flats with a Huion Light Panel

[bendiddley]

I want to start taking flats and have purchased a huion light panel but getting quite confused. So far I have only tried this indoors (in the dark obviously), with the camera on a tripod pointing at the light panel with the light panel on its lowest setting. I have experimented taking frames on AV mode which is what people say, but when I check the histogram it is always in the middle and I hear people saying it should be between 1/3-1/2 of the way over (also is that from the left or the right?). The only way to achieve this is to use shutter priority mode and adjust the shutterspeed but no one has mentioned doing it this way so am wondering if I am missing something here. I have tried using multiple layers of paper on it  as well to see if that helps but on AV mode the histogram is always in the middle. Also I hear people talking about ADU levels and setting this to somewhere between 20,000 - 30,000 but how do I do that?? Getting very confused. Just want some simple instructions so I know how to do this. Hope someone can help.

[Demonperformer]

My simple answer would be: if the histogram is in the middle, don't worry about it too much.

Yes, the prevailing wisdom seems to be 1/3 to 1/2 (from the left) and 20k-30k ADU. But I have also seen posts that suggest that the histogram should be as far to the right as possible, WITHOUT clipping the data (reaching the far right hand end), as this increases the dynamic range. Truth is, I don't have a good enough grasp on the theoretical to say if this is right or not.

At the end of the day, the only way you can tell if they are working or not is to apply a real set of flats to a real set of lights. But it sounds as if you should not be too far out.

[bendiddley]

Thanks. I think there was also something about shutterspeed too. If its too slow or too fast you'll see some kind of flicker of the screen or something from the refresh rate of the screen in the images. Do you or anyone else know anything about that?