I'm hoping I can get some better insight into how my camera works and how I can apply it in the future.
I have a custom built camera with a Canon EF 200 lens mounted to it. The camera allows me to hook a frame grabber to it and read out raw data into a file that can then be opened by excel. I need to correct the vignetting, so I took dark data (with the lens cap on) and light data (by pointing the camera into an integrating sphere). I then used that data to calculate the flat field gain table and applied it to one of the integrating sphere images. It worked as I expected and the imagery looks perfect - completely white, no rings or drop off at the corners. The entire time I was doing this, the aperture was set to f2.8 (fully open).
Now, when I went to apply my flat field gain table to the actual imagery I wanted to correct, I noticed that the images had been taken with different aperture settings of either 5.6, 8.0 or 11.3.
My question is, does this completely invalidate the flat field gain table I already calculated? Or is the change so minor it wouldn't be noticeable? Ideally I would just take another round of integrating sphere images, but I don't have access to that equipment anymore so I'm kind of stuck.