[Leica] lens reports 3,5/21 Ricoh, 4/25 Skopar, 2,4/50 Hexanon

[Erwin Puts <imxputs@knoware.nl>]

Ricoh GR 3,5/21 mm
Closely modelled on the historical Super-Angulons, this lens at full (3,5)
aperture gives a low to medium contrast image with a quite strong light
falloff, starting  half way the middle of the diamater. There is a slight
distortion in the corners.
This lens exhibits a  discernable bit of decentring and at this aperture
also is flare prone. Especially at the edges of strong pointlight sources
you can see halo-like degradation. On axis very fine detail is clearly
recorded, with  extremely fine detail detectable. In the field the image
details become progressively less sharply delineated when going to the
edges where fine detail is very softly rendered , but still visible.
Over the whole inage area very fine detail is rendered with  good
visibility. Stooping down a fraction to f/4 crispens the outlines a bit and
at f/5,6 we have excellent imagery over the whole image field with very
fine detail crisply rendered and a modicum of exceedingly fine detail
becoming detectable.
At f/11 we note a visible reduction in contrast. The very good performance
holds till 1 meter.
This lens must be rated above the (older) Super-Angulons and in itself is
an excellent lens.
In comparison the Elmarit-M 2.8/21 ASPH at full aperture presents a high
contrast image  with less light falloff, but a fraction more distortion. No
decentring and a much lower overall aberration content. On axis we see
exceedingly fine detail, that naturally  is less well recorded in the field
(zonal) part of the lens area. Still very fine detail is very crisply
recorded and extremely fine detail clearly detaectable.
At f/3.5 the image crispens noticeably and now exceedingly fine detail is
very well resolved over an image area with a diameter of 9mm.At f/4 this
performance extends over the whole field, but the corners are still soft.
Skopar 4/25.
This lens does not couple to the rangefinder and has a few fixed distance
tabs in the distance scale.
It shows decentring and the same type of flare as noticed with the GR 21.
Distortion is very low, but light fall off is visible, but not disturbingly
so. At full aperture the overall contrast is high and very fine detail is
crisply rendered over an image area with a diameter of about 6mm. Still
very fine detail stays visible over most fof the image area and becomes
barely detectable in te corners. Fine detail over the whole image area is
crisply rendered.  This excellent performance holds till f/8, and stopping
down further reduces contrast. Close-up performance is as good as the
infinity setting
In comparison the Elmarit 2,8/24 shows a high contrast image with
exceedingly fine detail rendered very crisply over an image area with a
diameter of 12 mm. Corners are soft with a slight flare prone
characteristic. After f/4 no improvements.
Hexanon 2,4/50.
This collapsible lens couples with the M rangefinder. Collimator checks
show an excellently accurate coupling. This lens has abit loose tube, which
flaws its performance. My comments are based on the correct positioning of
the tube. At 2,4 a high contrast overall image combines with a crisp
rendition of quite fine detail over most of the image area. At f/2,8 the
image improves very much an now exceedingly fine detail is rendered clearly
on axis and in the field. Corners stay weak as is natural. Stopping down
improves a bit, but the excellent performance holds till about f/8.
In comparison the Elmar-M 2.8/50 at full aperture is a shade softer and
extremely fine detail is clearly rendered.The outer zones however are
visibly softer. Stopping down the Elmar becomes the equal of the Hexanon,
but at 2.8 the Hexanon is indisputably the winner. IF its mechanical parts
were improved. Here we have a lens that challenges the classical and
redesigned Tessartype design.
The 1,2/60 deserves its own assessment and that is a bit long. So next time.

Erwin