Suppose I have a camera of sensor size 8mmx8mm, optical class (2/3)" with a compatible lens of also (2/3)". The focal length of my lens is fixed (say 8mm), and the distance to my target object is also fixed. My goal is to increase the resolution of my target object (I want my object to be represented by more pixels).
My questions are:
If I increase my focal length, am I also increasing the number of pixels on my object? or is the object just getting magnified? My guess is just magnifying.
If I increase my sensor size to 16mm, I think that means I'm increasing the number of pixels(resolution of the camera). So if 8mm means 2000 pixels for the width on my image, then 16mm means around 4000 pixels for the width of my image. In that case did I increase the number of pixels in my object? My guess is yes.
I was using this calculator on this webpage: https://www.scantips.com/lights/subjectdistance.html and when I put in the numbers, I realized both my guesses are wrong. It seems like because sensor size and pixel width of image are proportional to each other, increasing both doesn't actually increase the number of pixels represented on my object, but when I increase just the focal length and keep everything else constant then the number of pixels represented by my object also increases. I don't understand why though.