With 35 mm film cameras, the 35 mm refers to the film size, notto be confused with the lens size. A 50 mm lens is usuallyconsidered the normal or neutral size, with a magnific…ation factorof one. A 50 mm lens has no magnification. So, as the size(millimeters) of the lens become larger, the magnification of theimage becomes greater. A 100 mm lens gives 2 times magnification,and makes the subject appear 2 times closer and gives less viewingarea; a 200 mm lens gives 4 times magnification, and so on. .
A 25 mm lens would make the subject look farther away by afactor of 2 and give a wider viewing area. Fisheye lenses, usuallyabout 8 to 15 mm, give a very wide view and negative magnification.The increased area appears as a distorted "fisheye" view. .
Digital cameras have electronic image sensors which are usuallysmaller than the area of film exposed in a 35 mm camera, and lenseswill have a different magnifing effect. It is not a problem,though, as the manufacturer almost always gives a calculation ofthe equivalence of the lens with the digital camera compared to a35 mm film camera, and calculates the magnification of the lens ofthe digital camera. ( Full Answer )