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Message: <blockquote data-quote="oncebittern" data-source="post: 1431725" data-attributes="member: 68477">These figures refer to the focal length of the lens. In the good old days of film cameras, the 50mm lens that usually came as standard, was regarded as the norm. Longer lenses gave magnifications directly related to their focal length, so a 150mm would equate with 3x magnification, a 400mm with 8x magnification etc.So a 100-300mm zoom would give magnification between 2x and 6x, whereas a 75-300mm would give magnification between 1.5x and 6x.However, digital SLRs bring a further complication, in that many have a sensor that is physically smaller than the old 35mm film was, so using a lens designed for film, on a digital camera, increase the magnification further still. eg, in the case of my Nikon D80, I have a 1.5 magnification factor, so although I may be using a 500mm lens, which would give 10x magnification on a film camera, it actually produces 15x on my Nikon, of the equivalent of a 750mm lens.I do hope this hasn't confused you even more <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink    ;)" loading="lazy" data-shortname=";)" /></blockquote>