OK this might be a stupid question (most probably is) but I thought I should confirm it just the same. Lets say that on my quest to learn how to correctly expose slide film I want to try the average rule. Using the camera spot meter I get a reading for highlights/midtones/shadows and I want to use the average. So, I get 1/500 for highlights, 1/125 for midtones and 1/8 for the shadows (figures theoretical) what would be the average speed to use, 1/211 (meaning the actual closest possible) correct? Same if I want the same for only highlights and shadows, 1/254 right? Thanks In advance.