Thread: F1.2 pro glass
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Old 17th March 2019
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Re: F1.2 pro glass

Quote:
Originally Posted by MikeOxon View Post
I was surprised to read of such a large difference, so I checked with the Cambridge in Colour DoF calculator. Of course, DoF is not a 'hard and fast' calculation and depends a lot on how you define 'sharpness' but, using their rather strict criteria of viewing a 20" print from 25 cm (less than a foot away), the results I got were:


17mm at f/1.2, subject at 12': DoF= 2.95'

17mm at f/1.8, subject at 12': DoF= 4.5'



Significant, yes, but not as 'major' as you suggested. Also, if you were photographing a 'group' of people, might not the greater depth of field be considered more useful?
I was using the Depth of Field Calc iOS app, and settings for 15 - yes, as you say, this will depend a lot on how you define dof (which isnt a set quantity visually anyway, gradually fading away and also depending on a lot of light and subject variables).

Yes, I thought Id covered the two sorts of image I mainly take - one picking out a single person (for which f1.2 is ideal) and the other covering a group (all of which one wants in acceptable focus).

In the past I have fiddled about in PP trying to get a believable enhanced fall-off of focus with distance, but I gave up trying quite quickly. Maybe others have better PP skills than I, but after getting the 17 f1.2 I was able to stop worrying about it.
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