I know that when you are focusing closer than infinity say with a 150mm lens you need to think about the possibility of increasing your exposure due to the bell ows extension causing some light falloff. I also realize this depends on how clo se you are focusing , how much the bellows is extended and that will determine the exposure adjustment to be made. What I am curious about is when you have a 2 10mmm on your camera and focused at infinity your bellows would be extended to 2 10mm between the lens and the focal point on the film plane. With this lens focu sed at infinity you would not need to make adjustments for exposure but would ex pect the exposure to be correct based upon the f-stop and shutter speed for expo sure as indicated by a light meter reading.
Now say you put a 450mm lens on and the bellows needs to expand to 450mm between the lens and the focal point on the film plane. Do you need to make exposure ad justments due to the long extension of the bellows or I am just overly concerned by the visual impact of the bellows being expanded so much due to the 450mm len s?