jankap Offline Upload & Sell: Off
|
p.1 #4 · p.1 #4 · Opinions wanted on the Leica 180/2.8 Elmarit-R | |
You mean this one?
Jan
2.8/180, Elmarit-R,1980
The earlier version of this lens was a heavy-weight with 1300 grams. This redesign is
reduced in weight through the use of newer glass of anomalous dispersion and other
measures for weight reduction. At full aperture the lens delivers medium contrast
and coarse detail is rendered with clean edges over the whole image area, with the
corners being even better than the centre. Overall the performance is equal to that of
the replacement lens. Vignetting is slightly higher at 1 stop. Stopping down to 1:4
improves the contrast, but brings only marginal better definition of fine detail. From
1:4, image quality does improve very slowly, with an improved definition of very fine
detail on axis and a reduction of contrast in the field. Here one sees the effect of the
residual chromatic aberrations. Distortion is visible in the outer zones. This lens has
also improved performance at closer distances. The improvement in image quality
has been made possible by a reduction of lateral chromatic errors and the chromatic
version of astigmatism, which points already in the direction of the apochromat. Not
well-known is the thermic problem. Bigger glass elements, which are cemented or
tightly contained in a mount, will expand substantially when heated. The earlier
prototypes had some trouble here, as the glass has a tendency to crack due to
different thermal expansion coefficients. A careful selection of glass types is needed
to tackle this problem, which has relevance for all large lenses, which are cemented.
|