[GRM (Graham)]

Hello,

I have created Flat files for the first time and need some advice. How do I know they have been created correctly?
I have a Sony A7 connected to a Skywatcher ED100. I have placed a white table cloth over the end of the ED100 and placed a laptop with a white screen in front of it. I have taken 30 photos each at different exposures between 0.5secs and 2.5secs at ISO1000.

Using Nebulosity to measure the results.
0.5 Sec Exposure. Mean: 6245, Min: 2488, Max: 9652
1.0 Sec Exposure. Mean: 11933, Min: 4696, Max: 16372
1.6 Sec Exposure. Mean: 14678, Min: 7276, Max: 16372
2.0 Sec Exposure. Mean: 15368, Min: 9076, Max: 16372
2.5 Sec Exposure. Mean: 16114, Min: 11572, Max: 16372
I also did one with a LED torch in front, its results are
2.0 Sec Exposure. Mean: 16364, Min: 15860, Max: 16372

Can someone advise me on the results I should be aiming for. The LED torch images look saturated while the pictures taken with a laptop white screen gives me a variance of greys.
Kind Regards
Graham Galea.