Thread: F1.2 pro glass
View Single Post
Old 17th March 2019
drmarkf's Avatar
drmarkf drmarkf is offline
Full member
Join Date: Aug 2008
Location: Cambridge, UK
Posts: 5,647
Thanks: 360
Thanked 508 Times in 422 Posts
Likes: 2,219
Liked 1,281 Times in 728 Posts
Re: F1.2 pro glass

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.

Too much Oly gear.
Panasonic GM5, 12-32, 12-35, 15. Laowa 7.5.
Assorted legacy lenses, plus a Fuji X70 & a Sony A7S.
Reply With Quote