I'm interested in being a AAVSO contributor. I'm attempting to take the first step and test the linearity of my Nikon d7500 camera. Following the DSLR manual I have a uniformly lit light source (an LED tracing panel that has been used successfully to take flats). I have been taking exposures at iso 100 and f32 at 2 min intervals. I used my imaging software siril to convert the RAW (nef) files to FITS and measure the mean ADU values of a 200 x 200 pixel area in the center of the flat. Siril doesn't allow measurements of the RGB image only the separate red, blue, green channels. I have plotted the data points and and am not getting a linear graph. when I add a tread line to confirms directly with a moving average tread line. for some reason the "add a new file" is greyed out for me, otherwise I have an excel file I can show. Can anyone tell me what I'm doing wrong? I am a MAC user with both apple silicon and intel computers.
Thank you so much,
Hello! Perhaps this post can be moved to the photometry forum where more folks with DSLR experience might see it and give guidance? Best regards. Mike
Yes, thank you for pointing me in the right direction