[Leica] DR contrast

[photo.forrest at earthlink.net (Phil)]

I love my DR and my Rigid Chrome Summicrons. The DR is the lens I will
own if all the others were to have to go away.

I think much of the "softness" lore these days may have to do with the
state of the particular sample of lens itself. Many have some very
significant coating marks and fogging is not uncommon either.

I agree though, that the lenses perform fantastically. On the M8 they
are incredible.

Phil Forrest


On Thu, 23 Sep 2010 15:36:05 -0400
"Seth Rosner" <sethrosner at nycap.rr.com> wrote:

> Scanning the batched conversations I came across this one that caught
> my eye and about which I have some significant knowledge. Some on the
> list may recall my writings in LHSA's Viewfinder magazine several
> years ago contradicting Erwin Puts' statements about the series of
> 50/2 Summicrons. One of them even resulted in marc small accusing me
> of libel and predicting that Erwin would sue me. Poor lawyering on
> marc's part as truth is an absolute defense to a defamation
> action.  ;-)
> 
>  
> 
> My purpose here is to dispel a very widely held opinion that the 1956
> DR/Rigid 50 Summicron is a low-contrast lens. It is not, except when
> compared to the latest Leica and other lenses at wider apertures. Ten
> years ago I had correspondence with Lothar Koelsch, then head of lens
> design at Leica, about this very issue and received from him
> print-outs that I have in my hands as I write, of the MTF curves
> calculated by Leitz/Leica Camera, for the 50/2 lenses from the
> Summitar through the DR/Rigid, 11817 (1969) and the 1979 version that
> I believe is still current. 
> 
>  
> 
> Bear in mind that every lens is a compromise, that there is no such
> thing as a perfect lens. If there were, such a lens would perform
> flawlessly at full aperture and as a photographer stopped down, the
> image would degrade progressively because of diffraction! So the
> designer has to decide in which direction he/she wishes to correct
> for most, since one cannot correct all aberrations simultaneously.
> The DR/Rigid concedes some softening contrast at f/2 and 2,8 in order
> to correct more highly for spherical and chromatic aberrations and
> thus achieve significantly higher resolution. Geoffrey Crawley, then
> Editor-in-chief of the British Journal of Photography, confirmed to
> me in our correspondence in the late 1960's, that due in some
> significant part to the emphasis put upon contrast by the great
> Japanese manufacturers, principally Nikon and Canon, that seemed to
> have persuaded a large number of photojournalists to favor highest
> possible contrast (keep in mind that most of these folks did then and
> still do tend to shoot wide open most often, eh Tina & Ted?), Leitz
> designed the 1969 50 Summicron #11817, for max performance at f/2.
> And wide open, looking at the MTF charts, no question the contrast of
> 11817, especially at the lower spatial frequencies
> - 5, 10 & 20 line pairs/mm is significantly better than the DR. At
> f/2,8 it is better than the DR but only on axis; at the near and far
> edges the DR's contrast is superior and at f/4 and 5,6 it is markedly
> superior, again except directly on axis. As to the current 50
> Summicron, contrast is somewhat superior at the first three stops
> whilst the resolution of the DR at medium apertures is better than
> both later Summicrons. 
> 
>  
> 
> >From Leica's own  MTF charts it is clear that the myth of the
> >DR/Rigid lens
> being soft and low-contrast is just that - a myth. Use that lens at
> f/5,6 & f/8 and even at f/4, and you have an extraordinary
> image-maker. And using a rigid 50 on an M8 as I do is even better,
> since it eliminates the outside quarter of the image circle wherein
> lies the vast majority of the design's "softness".
> 
>  
> 
> Just my 2c.
> 
>  
> 
> Seth 
> 
> 
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