11-01-2010, 10:12 PM
[quote name='Brightcolours' timestamp='1288614014' post='3864']
Not true. Same aperture, same field of view, SAME DOF.
Aperture is measured in mm's. f-values are focal length divided by aperture.
[/quote]
Ah, yeah, now we're splitting hairs, are we? I meant to say f-stop. DoF depends on reproduction ratio and f-stop. APS-C has a smaller sensor, ergo smaller reproduction ratio for the same composition, ergo more DoF.
Well, the problem is that if you want shallow DoF, at some point you're wide open, and as far as I can tell, nobody has made a 35/1.0 APS-C lens at a reasonable price to match the shallow DoF capabilities of a 50/1.4 FF, or a 60/1.0 APS-C to match a 85/1.4 FF. Now what's strange about that?
Not true. Same aperture, same field of view, SAME DOF.
Aperture is measured in mm's. f-values are focal length divided by aperture.
[/quote]
Ah, yeah, now we're splitting hairs, are we? I meant to say f-stop. DoF depends on reproduction ratio and f-stop. APS-C has a smaller sensor, ergo smaller reproduction ratio for the same composition, ergo more DoF.
Quote:Your proposition is a bit strange: One chooses an aperture to get the desired DOF. One does not choose an f-value just to take it as "standard across sensor sizes".
Well, the problem is that if you want shallow DoF, at some point you're wide open, and as far as I can tell, nobody has made a 35/1.0 APS-C lens at a reasonable price to match the shallow DoF capabilities of a 50/1.4 FF, or a 60/1.0 APS-C to match a 85/1.4 FF. Now what's strange about that?