Im confused lol, so the blades dont change the opening during macro focusing?? what about during normal behavior, my lense is still F3 for almost everything except 10 feet and infinity..Josh, no. The Nikkor Micro lenses are designed to accurately communicate the value of the actual f-number to the camera as they focus closer. Other close-focusing Nikkors (such as the 35mm f/2) do not. But when the 60mm says f/3, 4 or 5, it actually is getting less light onto the sensor, and thus needs to use the higher f-number to calculate the correct exposure. With non-micro lenses, the difference between the stated f-number and the effective f-number is not great enough to effect the exposure. It can change up to a third of a stop with out a noticeable difference.
What doesn't change is the actual diameter of the lens opening.