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Anonymous
>>177139 You are. For 135 film (normal 35mm, etc.), the "perfect normal" that gives the same look as the human eye is 43mm. Early on, we're talking the very first 135 film cameras, it much easier to make a good lens a little longer, so they settled on a clean 50mm as the approximate target- lenses are almost never exactly their lengths; most "50mms" are really like 51.something.
Normal lenses, as a class, span from 40mm-60mm. Outside of this range, you have wide angles that expand space and telephotos that contract it. Wide-angles go up to <40mm, and there's a subcategory of "superwides" that are all lenses <28mm.
Telephotos- properly called "long focus" lenses, telephoto is a specific sort of optical design used in almost all long focus lenses- are anything 60mm<. There's two subsets here: medium telephotos, between 60mm and 135mm, and supertelephotos, from 200mm (though some say a little longer) up.
Divide or multiply these by the difference in size between 135mm film and the format in question to get the right focal lengths. For example, a 28mm lens on a DX sensor is the same as 42mm on 135 film- almost exactly the perfect 43mm, and since most 28mm lenses are .something longer, awfully close. A 50mm on any of the digital sensors he has is a medium telephoto. On medium format film, it's a wide angle.
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