Hi all,
From: "CyberSimian" <OlySimian@xxxxxxxxxxxxxx>
>
> I purchased my first two Olympus OM lenses from R.G.Lewis in the 1970s. At
> that time, R.G.Lewis had a TRULY unique USP(!) -- they tested all of the
> SLR
> lenses that they sold new.
Very interesting!
> >From my files, here are some test results for actual lenses, garnered from
> looking in their shop window every few weeks; figures are "effective" lines
> per mm at centre/edge, for apertures: max aperture, f4, f8:
> <snip>
> For comparison, here are the figures for the two lenses that I purchased
> (figures for zoom are f4 and f8; figures for 28mm are f3.5, f5.6, f8):
>
> Olympus 75-150mm f4 @75mm: na, 96/62, 96/84
> Olympus 75-150mm f4 @150mm: na, 96/62, 96/88
> Olympus 28mm f3.5: 104/74, 112/92, 120/96
>
> I still have the zoom, but sadly not the 28mm which got damaged (it was
> clearly a cut above the performance of other 28mm lenses that I saw in
> R.G.Lewis shop window).
>
The 28/3.5 is indeed a very fine lens. Although the later (and surprisingly
simpler optically!) 28/2.8 is quite sharp and contrasty, both units I had of
the f/3.5 were just better.
> But with a soft
> lens, it can happen that even fairly coarse lines are not really sharp, but
> nevertheless quite fine lines can be seen, perfectly detectably, through a
> kind of haze of background fuzz.
That's right, the resolution figures alone only tell half the history!
That's what MTF curves are for... and still don't tell the whole thing.
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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