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What does "true focal length" of a lens refer to?
I know about the crop factor and comparisons to 35mm camera equivalents, but recently I was wondering, when people talk about true focal length, does that refer to the number written on the lens, the 35mm equivalent, or the focal length with the crop factor applied?
So differing answers here...anyone care to elaborate? Is the number written on the lens also the 35mm equivalent?
Is "true" focal length even a standardized term that means the same thing for everyone?
3 Answers
- sant kabirLv 71 decade agoFavorite Answer
The focal length of the lens does not change by putting it on different sensor-sized camera bodies. as far as optics is concerned. ''Only the field of view changes''. So, comparisons, equivalents and factors become a relative term. The true focal length or focal length is one and the same and yes, it is written on the lens.(nothing to do with 35mm equivalent!)
- Anonymous1 decade ago
It's whatever is on the lens. A 50mm is a 50mm is a 50mm. Never changes.
