Focal length is an indication a lens’s magnification or angle of view and it’s quoted in millimetres. Sometimes the makers quote actual millimetres and sometimes they quote the ‘effective’ focal length, which is what the lens would be equivalent to if it was a 35mm camera. This is necessary because cameras come with different sensor sizes, so the angle of view of a lens changes according to the camera’s sensor. Today, photographers still talk about focal length in 35mm camera terms, using the focal length to characterise lens types – so a focal length of 28mm or shorter is a wideangle lens, a 35mm is a ‘moderate wideangle’, a 40-60mm lens is a ‘standard’ lens, and a lens of 70mm or longer is a telephoto (you get ‘short’ telephotos, medium telephotos, long telephotos).
You are here: / / Focal length