Gerard Maas wrote:
> Thomas wrote:
>
> > Just for clarification: At what magnification did they test? I guess macro
> > range ?!
> >
>
> They didn't say. Does that matter for a MTF test? I seem to remember that those
> test are performed with the lens set at infinite. (but my memory is not to be
> trusted anyway!! :-)
Yes, it matters. Especially in this case. Just like non macro lenses
aren't optimized for high magnifications, macro lenses aren't optimized
for infinity focus. Now, with modern internal focusing/floating elements
lenses, the difference isn't as big anymore as it once was with lenses
focusing by extension. Still, there is a measurable difference in MTF
values at different focusing distances. Making the best compromise is
what lens design is all about.
Typically, a test for macro lenses would be done at 1:2 or even 1:1
magnification, while for other lenses focusing distances of 100 or 200
times focal length is most common AFAIK. Some, like photodo, use
infinity setting. I have even seen some tests where both, close up
and "normal" range were tested for macro lenses. And the curves were
quite different.
Thomas Bantel
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