people
my 50mm 1,8has a very high s\n:5,xxx,xxx;when was it manifactured?
thankss,Nicola
----- Original Message -----
From: John A. Lind <jlind@xxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, January 08, 2001 1:42 AM
Subject: Re: [OM] 50mm Lens Versions
> At 03:23 1/8/01, C.H. Ling wrote:
>
> >The SC 5xx I have is an exceptional one, which is the best 50/1.4 (in
> >resolution) I have ever seen.
> >
> >One point I'm not quite sure, seems that starting from 5xx,xxx the
> >construction of 50/1.4 was not changed (except coating), the different
> >in performance might be came from the manufacturing, as the production
> >quantity of 50/1.4 was very high, tooling or fixture might wear and
> >changed a few times during the whole manufacturing history.
> >
> >C.H.Ling
>
> I will second C.H. Ling's observation about manufacturing variation and
> tooling wear. I know it all too well with what I do professionally in
> electronics manufacturing.
>
> I will add that performance variation can also occur in used lenses with
> their varying condition and generally unknown provenance. A lens may have
> been damaged and repaired to excellent cosmetics but not to original
> optical specifications. It is a risk the buyer of any used lens takes,
> unless the complete provenance of the lens is known, which is quite
> rare. Additional variation among a range of user observations about
> performance can also be caused by the fact they are used on different
> camera bodies. There _will_ be some variation in focusing accuracy
(flange
> to film plane distance versus flange to mirror to focus screen distance)
> which _will_ confound lens performance. What makes Gary Reese's data
> valuable is generally consistent use of the same set of camera bodies in
> his testing . . . which is why I'm glad he has posted which body was used
> for each test.
>
> While my 50/1.4 MC with 789,### S/N is second to my 50/1.2, it is a very
> close second, and both are much better than the old 50/1.8 F.Zuiko I
bought
> in 1980. I'm not that surprised that C.H. Ling has a 500,### S/N that
> performs better than all the other 50/1.4's he has. All the other sources
> for possible variation in performance can dominate theoretical differences
> inherent in the designs when you compare specific lenses.
>
> The evidence shows some measurable probability if a specific 50/1.4
"Zuiko"
> has a S/N >1,100,###, it will be a better lens than a specific "MC" with a
> S/N <1,000,###, or a specific "G.Zuiko" but it is definitely _not_ a 100%
> guarantee that it will be. I believe this is all one can legitimately
> conclude from Gary Reese's testing: statistical significance between the
> mean performance of entire populations of different versions of the 50/1.4
> Zuiko.
>
> -- John
>
>
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