08-08-2011, 12:33 PM
[quote name='karlmera' timestamp='1312804546' post='10498']
But is that logical?
[/quote]
Yes, that is the nature of MTF tests. The test target must have a certain specific size on the image frame for the measurements to make any sense. Everyone does it that way, just the nature of the measurement beast. And macro lenses of course are not only used for macro photos.
It is not as if macro lenses get to be less sharp all of a sudden when you focus closer...
There are a few exceptions, which are not that consistent. Like my Nikkor 55mm f3.5 micro 1:2 macro (1st generation). It is said to be one of the, if not the, sharpest Nikon SLR lens, but only at macro distances. Its performance breaks down when used as non macro lens. More modern macro lenses have a design which prevents that.
But is that logical?
[/quote]
Yes, that is the nature of MTF tests. The test target must have a certain specific size on the image frame for the measurements to make any sense. Everyone does it that way, just the nature of the measurement beast. And macro lenses of course are not only used for macro photos.
It is not as if macro lenses get to be less sharp all of a sudden when you focus closer...
There are a few exceptions, which are not that consistent. Like my Nikkor 55mm f3.5 micro 1:2 macro (1st generation). It is said to be one of the, if not the, sharpest Nikon SLR lens, but only at macro distances. Its performance breaks down when used as non macro lens. More modern macro lenses have a design which prevents that.