On Tue, Oct 31, 2000 at 12:36:41PM +0000, Giles wrote:
> frieder.faig@xxxxxxxxxxxx-stu wrote:
>
> > Well, coner quality isn`t a real issue to justice this type of lens! They
> > are designed to shoot 3D scenes and not to reproduce flat objects ( =
> > test board). The lens designer often resign to correct the focus area
> > exact even, to get better over all results. When you want exact even
> > field (=sharp corners) use a Macro lens.
>
> I do not think you are entirely correct. The 50/1.2 would appear to have
> very good performance from centre to edge, going by tests done by
> Photography magazine and Modern Photography. In particular, it would
> appear to have very much better performance at the edge than the 55/1.2.
Well, Maybe I was troubled to express myself correct in foreign language.
I should a have a special photographers dictionary. But the tope event helped
me.( Special thanks to Marco)
I didn`t wanna say anything about performance of any lens at all. I just wanted
to point at the problem called 'the eveness of the field of focus'.
It matters this type of lenses most because the shallow d.o.f. wide open.
When stopped down it`s not so critical.
When the field of focus is curved it decreases edge performance
when you`re doing test shots. But it is not that importend when you`re doing
real-life photography. This is why a lens designer don`t pay too much attention
to this, because he know`s it is not so imprtand for typical use of a fast lens
(Macro lenses are a total different matter)
So I think when you`re only locking at edge performance when searching a
fast lens
you might fool yourself because a very good real-live performer is looking bad
in the corner.
Now some words to the F/1.2 Zuikos: (I never used any of them)
A european photo-magazin MTF-meassured most SLR-lenses from 1980 ~ 1983.
The most of the Zuiko´s are among the upper group, but not on the top.
Two exceptions:
1.) 55mm/F1.2 by far best MTF-values of F/1.2-group.
2.) 50mm/F 1.4 (SC!) It is in the lower end. Don`t get me wrong: The MTF-curves
are not as good as some competitors, but the 50mm/F1.4-group is close together.
And I think stopping down only to F/2.8 only wasn`t an advantage for this
Zuiko.
The 50mm/F1.8 (MC-Variant) was unlucky, it competed well, reached the top
group,
beated the Zeiss, almost reached the Leitz R-Summicron, but then all SLR-lenses
were outstipped by the Leitz M-Summicron 2.0/50....
Another aspect: IMHO Olympus continously improved their lens design without
making
lot of noise about. (When I was new in the OM-area, I once asked a salesman of
a photoshop
- specailists for used gear- About different versions of the 1.4-Zuik:
He sad: No versions, Olympus always built the same 50mm/F1.4! - Ooohhh.......)
But when The 55 mm/F1.2 -lens was replaced by his 50mm sucessor, Olympus said
that
this was done, because the new version is better. - Any Questions?
Frieder Faig
>
> The 50/1.4 MC would appear to be a close match for the 50/1.2 but the
> latter would appear to have more even performance from centre to edge and
> to have better contrast performance on the whole, based on the the first
> set of test data below, courtesy of Shawn Weber.
>
> This also is borne out by the Modern Photography tests of the 50/1.2 - the
> second set of test data reproduced below. At F8 the contrast numbers are
> 78 in the centre and 74 at the edge. Looking at their tests of other
> Zuikos these contrast numbers would appear to be the highest of just about
> any Zuiko they tested!
>
> Of course one shouldn't depend too much on test data, but bar being able
> to borrow lenses and try them out ourselves, we haven't much else to go
> on, except perhaps George Andersons anecdote about having a photograph
> taken with a 50/1.2 published in a National Geographic calendar and the
> editor phoning him to ask him what lens he had used ;-)
>
> The test data below does not appear to concur with Gary Reeses tests of
> multiple samples of the 50/1.2, where I believe he found a >1,100,000 SN
> MC 50/1.4 to have superior resolution, however, I thing the strong suit of
> the 50/1.2 is its contrast performance, not outright resolution.
>
> I think Doris could even find a use for a 50/1.2 - wide open ;-)
>
> Giles
>
>
> -----------Courtesy Shawn Weber---------------------------------------
> As a result of some of the questions regarding the performance of the
> various Zuiko standards, multi-coated(MC) and single coated(SC), I dug
> around in my magazine collection and came up with an issue of
> Photography(March 1983) that tested out all six Zuiko 50s. I shall
> summarise the results below :
>
> Key : C=Centre, E=Edge, Hi=High contrast target, Lo=Low contrast target
> Results are cycles per mm
>
> 55/1.2(SC) C/Hi C/Lo E/Hi E/Lo (7 elements/6 Groups)
>
> 1.2 36 21 24 18
> 2 54 33 27 27
> 2.8 60 42 30 30
> 4 66 42 36 36
> 8 66 48 36 33
> Tester's comment: Distortion low, flare not as good as 50/1.2
>
> 50/1.2(MC) C/Hi C/Lo E/Hi E/Lo (7/6)
>
> 1.2 42 36 42 30
> 2 60 42 48 36
> 2.8 66 54 54 48
> 4 72 60 66 54
> 8 66 60 72 60
> Tester's comment: great performance regardless of speed, distortion,
> flare low
>
> 50/1.4(MC) C/Hi C/Lo E/Hi E/Lo (7/6)
>
> 1.4 54 42 48 33
> 2 60 48 48 33
> 2.8 72 60 60 48
> 4 72 54 54 54
> 8 72 66 54 54
> Tester's comment: Very good overall performance, good flare resistance,
> mild barrel distortion.
> ---------------------------------------------------------
>
> Modern Photography
>
> 50/1.2 MC (11/83 p. 131): Resolution (lines/mm) at 1:50x
> 1.2 2 2.8 4 5.6 8 11
> 16
> Center: VG 45 Gd 50 Gd 56 VG 63 VG 63 VG 63 VG 56 VG 56
> Corner: Ex 35 Ex 40 Ex 45 Ex 50 Ex 56 Ex 56 Ex 50 VG 45
>
> Contrast (%) at 30 lines/mm
> Center: Hi 58 Hi 60 Hi 64 Hi 68 Hi 76 Hi 78 Hi 75 Hi 67
> Corner: Med 26 Med 30 Hi 44 Hi 60 Hi 73 Hi 74 Hi 66 Hi 81
>
> --------------------------------------------------------
>
>
>
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