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can diopters far and close focus charts be generalized for the same focal lenght but different sets of lenses?

diopters charts

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#1 davide sorasio

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Posted 18 July 2017 - 03:40 PM

Hello everyone, maybe this is a silly question but it has been in my head for a while.

Once I have a close and far focus chart for a certain focal lenght, could it be used for the same focal lenght of another set of lenses that have the same T-stop when wide open? For example, shooting at the same settings on the same camera with a 75mm Master prime using a diopter +1 would give me the same far and close focus if switching to another lens with the same wide open T stop?

and if not, which are the factors that influence close and far focus on diopters except from the diopter's gradation?

Thanks in advance


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#2 Kar Wai Ng

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Posted 19 July 2017 - 02:06 AM

If the other lens is a 75mm Master Prime, then you would have the same near and far focus point; with another make of lens like a Cooke 75mm, however, you would have slightly different results because the entrance pupil is different. I don't think it would be dramatically different. A +1 diopter would still put your infinity at 1 meter in front of the diopter, theoretically.


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