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Old Feb 9, 2008, 1:09 PM   #1
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I have a set of nikon 4T and 5T and have used them fairly well over the last year. Unfortunately I have no idea of their Diopter or focal length. A search on the web shows varying answers to this question. can anyone give me a difinitive answer to this question?

Note, the focal length is not written on the lens's.
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Old Feb 9, 2008, 6:34 PM   #2
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Nikon do not even print any hint on their close-up lenses. For example, the better Nikon close-up lenses are #3T, #4T, #5T and #6T, where #3T and #5T have diopter +1.5 and #4T and #6T have diopter +2.9.


A dioptre, or diopter, is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (that is, 1/metres). For example, a 3 dioptre lens brings parallel rays of light to focus at 1/3 metre.
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