A novice here, asking what the ED means on the lens. Looking at a 70-300 f/4.5-5.6G ED-IF VR. I know what the numbers mean, and the VR, but the ED-IF is puzzling. I am trying to get this for my granddaughter who is a photo enthusiast!
ED is "Extra low dispersion" glass, formulated and coated to minimize chromatic abberation (a phenomenon that will degrade your photo's sharpness). IF is "Internal Focusing." This means that the length of the lens does not change when focusing. Generally this means that the front element of the lens will not rotate or move toward or away from the camera body while focusing. This can be particularly important when using accessory filters (for example, graduated neutral density filters) or while doing macro work.