Re: [Leica]summitar performance at f2

["A.H.SCHMIDT" <horsts@primus.com.au>]

Jan C. Schuller wrote:
Hello everybody,
I recently I started to use a Summitar 50/2 with a iiic. While producing
a series of shots at different f-stops, I noticed that at f2 - f5.6 the
sharpness in the edges of the image is rather poor. However, it increases
with increasing f value and is ok from f5.6 to f8 onwards. I know that
the
performance of those lenses is not comparable to contemporary ones.
However I'd like to know to what extent the low edge performance is 'normal'
for the summitar. (I also own a 90/4 Elmar where the edges are ok regardless
at any given f-stop).
I'm thankful for hints of all kinds.
Yours Jan


Jan,
Leitz released the Summar and later the Summitar not to be used wide
open, just because it had (for its time a relatively large f-stop), but
to use it only, when the light situation demanded it. Leitz in their early
literature states this. They also warned, that these lenses, when used
fully open, should definitely be used with the correct lens hood.
Often, you can read on the LUG complaints about the flare problems with
this lenses. This however is minimized when the orrect hood is
used. By correct, I mean, the one specified by Leitz.

I do own all the above lenses. An uncoated and a coated Summar, and
the Summitar.
I really did not have any problems with flare, unless the sun shone
right in to it. Most other lenses have problems under this circumstances.
I believe, that later lenses scatter a lot less light inside the barrel.
This probably helps to increase the contrast, but it does not make the
earlier lenses unusable. Both the Summar and the Summitar especially
perform very well at about f 4 and smaller. I am even not so sure, if
the edge sharpness is always so extremely important or in some cases so
desirable. The most important part of your composition is normally in the
centre of the picture.  If you glance at a large print, it actually
takes some effort to look to the edges of the print. I can see the need
for this extreme sharpness over the whole of the print for example in industrial
use or some advertising. However I don't think the Leica is the camera
for this type of photography anyway.

Regards, Horst Schmidt