Erwin Puts on the 50/2.8 Elmars (source:
https://web.archive.org/web/20130310125550/https://furnfeather.net/books/pdf/llcforweb.pdf):
6.3.3 2.8/50,Elmar,1957
This lens was redesigned with the new Lanthanum glasses, used also in the
Summicron version and the LaK9 glass can be found in the first and last element.
Analysis by modern computer based design programs of the original Elmar
configuration show that the basic design is difficult to improve upon. A tribute to the
old masters no doubt.! If advances are to be made, the only route is the glass
selection. Inevitably, older glass types were removed from the catalogues and so the
designers were forced to adapt to these circumstances. But modern optimization
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analysis also shows that the gains are relatively modest and so it may be no surprise
that the image quality of this lens is quite stable over the years. Of course newer
glasses and specifically the coating of surfaces give a modest gain under adverse
conditions. In many situations, the use of new glass types will not improve the basic
performance of a lens, as the designer will adapt the lens specifications to the
characteristics of the new glass in order to preserve the original image quality. The
classical four-element/three group design of the Elmar can just cope with the most
important aberrations. And we know that doubling the aperture will increase the
effect of aberrations by at least 6 to 8 times. The designer has however limited
optical means to correct this higher level of optical errors. The Leitz designers used
the new glass to improve the lens, but the progress is modest. The moving tube for
the collapsible mount made the lens mount a bit unstable and Leitz indeed designed
a newer rigid version with much better image quality. This elusive Elmarit
1:2.8/50mm never went beyond prototype status, but should have been an excellent
design.
Figure 88: diagram 47
At full aperture the lens has a low overall contrast, lower than that of the Summicron
and the Elmar 3.5 version. Coarse detail is reproduced with soft edges and finer
detail is blurred in the outer zones (beyond image height of 8mm). The aperture of
1:2.8 does overstretch the design and spherical aberration and flare (due to coma) do
lower the contrast. It delivers however an even performance over most of image
field, which improved rapidly when stopping down. At 1:4 the performance is very
good and better than that of the original Elmar 1:3.5/50mm at 1:4. Overall contrast
becomes medium and now we have a very good centre quality, with he outer zones
still trailing behind. Compared to the Summicron (I), there is an interesting
difference in fingerprint. The Elmar has the edge in the centre of the picture and the
Summicron is better in the field. At 1:8 we find very fine imagery (as good as that of
the Summicron (II) from 1957). The performance characteristics show the limit of a
four-element design with the glass types then available. Vignetting and close-up
performance.
6.3.4 2.8/50,Elmar-M, 1994,
Introduced in 1994 as a special lens, only to be sold in combination with the M6J
body, it has evolved into a normal , but underrated, catalogue item since 1996.
Production however was continued during 1995. The image quality of this
completely redesigned lens is amazingly good and now the position of the stop is
between the second and third element. One might assume that the 4 element design
has been fully explored and in a sense that is the case. Still the Leica designers could
extract more performance out of the design, showing that improvements are always
possible, . The ergonomics of the Elmar-M do limit its use. The external design very
closely resembles the previous version, and inherits its small aperture ring and
distance ring, presumably necessary for the compact size when collapsed. The lens
mount is non-rotating.
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Figure 89: diagram 48
At full aperture the Elmar-M adds medium to high overall contrast to the image.
Fine detail is rendered crisply over most of the film area and fine detail is recorded
with great clarity and sharp edges. This behaviour is interesting when compared to
the Summicron (III) from 1969, at aperture 2.8. The overall performance is
comparable, with the Summicron having an advantage in contrast. But in the field
(zonal areas from image height 9mm) the Elmar has clearly the edge. The
Summicron has better imagery in the centre (contrast and rendition of fine detail),
but the Elmar records fine textures with greater clarity in the field. Stopped down to
5.6 or 8.0, the Elmar improves visibly with a higher contrast and consequently better
rendition of (now) very fine detail. The fingerprint difference with the Summicron
holds at these apertures too. Only in the extreme corners the Summicron has an
advantage. Compared to the older Elmar, we see the progress when we look at the
capabilities of recording fine detail, which is excellent with the new version and
moderate with the previous version. Vignetting is more visible with the Elmar-M
than with the previous version and identical to the current Summicron (IV), stopped
down to 1:2.8. Close-up performance, even at full aperture is excellent with the
Elmar-M, but less so with the previous Elmar-version.