I should clarify that imaging is at the resolution limit of visible light. I have based my calculations on the following link.
https://www.ibiology.org/talks/resolution-of-a-microscope/#:~:text=00%3A16%3A14.08%20will%20be%20in%20your%20microscope.&text=00%3A16%3A17.16%20a%201.4,16%3A23.27%20is%200.22%20microns.
I used 400 nm for the wavelength because some light will obviously be at this wavelength. The problem is that I am concerned that using 400 nm wavelength is overkill because phase contrast light microscopes highlight fine details that are likely to be pertinent to visible light above 400 nm, but I am not so sure about this. There is a big drop in megapixels needed if I go up to 500nm. Is there a correct or standard way to do this so that I don't risk losing information but I don't end up using up tons of additional megapixels that barely make a difference. Over 1000 specimens will be imaged, so it makes sense to get this right before we start the imaging.