On Mon, Jul 22, 2002 at 04:19:13PM -0700, Winsor Crosby wrote:
>
> I found a key in one of the Color Foto pages that answered by
> question. Dotted lines are tangential and solid are sagittal.
Yes, mostly only in the two latest tests, they changed their diagrams
again, and averaged tangential and sagittal to one line, but printed
the values of two appertures in one diagram. -> see remark(4)
>
> Interesting that the 200/5 comes off better than the 200/4 in this
> kind of test when it is usually used because of its light weight and
> small size in spite of not being considered quite as good as the
> 200/4.
Another hint for the interpretation I forgot last evening:
at 5 + 10 lp/mm differences of 5% are visible in the results.
When the lines differ less than that, the difference in image
quality is mostly not visible.
At 20 lp/mm a difference of 10%, and at 40 lp/mm differences
of 25% are necessary to make a difference.
This are rough reference values published with the tests.
When I take this into accout, the practical differences between
the 200mm lenses dissapper. What my experience with this two lenses
is. But I´m not surprised that the F5 lens comes out better though
its optical construction uses more elemtents for less speed.
>The choice of wide open and 2 stops in seems to penalize fast
> lenses. The 21/2 which most tests and experience indicates is
> superior to the 21/3.5 comes off worse. And then it is compared to a
> slow Leica and a slow Zeiss superwide and also does not do that well.
Yes, all lens testing sucks in one or another way. I`ve kept this tests
since some years. And really appreciated, when I found Gary´s OM
lens testing in the net, because his tests include all F-stops, giving me
a hint how to use a lens, what the MTF-tests don`t although they
notify very subtile differences.
Yes, penalization of faster lenses is obvious in some tests. compare MTF
of 2/21 @ F4 and the 3.5/21 @ F3.5, and they are about equal in summary
although very different in charateristic. This is a good result for the
remarably
F2 lens, but is it fair to the F3.5 ?
I think the Zuiko 1.4/50 is hitted hardest by the two stops dom rule, compared
to the 1.8-Zuiko which was tested at F4, almost the peak of the lens, and
the F1.2/55mm lens, which seems very well optimized for wide apperture use.
> One would guess that the 21/3.5 would come out about the same as the
> Leica and Zeiss.
Which Zeiss? I have no tests of a 21mm Zeiss, but well the Leica
Superangulon is really exeptional especially cause its wide open
performance is similar to stopped down. The Zuiko 3.5/21 has compairabel
performance stoped down, not wide open. But overall this lenses are clearly
top of 20/21mm lenses.
Just a bit what I think about the tests.
Frieder Faig
> --
> Winsor Crosby
> Long Beach, California
>
> ?
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