I also agree MTF is a very useful tools and the charts are much more
useful then the overall rating. bUT I have one question, does any one
know how Photodo check the MTF of center and edge? what important is
will they refocus on the edge before they take the reading? If a lens
has high field curvature then the edge MTF will be very poor (because
you focus only at the center) but the real picture on the field may
not be that bad.
The Leica M 50/1.4, 35/1.4 and 75/1.4 were tested to be having very
high field curvature by Popular photography, the SQF were very low at
F1.4 and F2.
C.H.Ling
Mark Hammons wrote:
>
<snip>
>
> MTF testing, while not an end all, is still an extremely useful parameter for
> lens quality.
> I work at Raytheon on FLIR (Thermal imaging) systems and believe you me, MTF
> is
> a key parameter that is looked at in an optics design and in guaging image
> performance.
>
> I think what might be a little strange is the way Photodo.com comes up with
> their "overall" number.
> For any members that haven't done so, read the comments at the photodo.com
> site that explains MTF
> and in particular how they come up with the values they do. I usually
> ignore the "overall" number and look at the 2 or more charts -- that tells
> much more of
> the story.
>
> Mark
>
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