Archived posting to the Leica Users Group, 2008/08/30

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Subject: [Leica] question to Steve Barbour concerning dual range summicron
From: len-1 at comcast.net (Leonard Taupier)
Date: Sat Aug 30 06:57:27 2008
References: <5.1.0.14.2.20080829224920.00c54e10@mail.threshinc.com>

Peter is absolutely correct in his assessment of the two lenses.

Resolution tests are normally made at the lens infinity setting using  
sophisticated optical measuring equipment. I have tested both of  
these lenses using test charts at the required distance of 8' 3" from  
lens to chart for a 50mm lens. I find that when using an M8 for the  
test that the resolution is limited by the M8 resolution and not the  
lens. At the 8' 3" distance I find the resolution of the two lenses  
from f5.6 to f11 to be the same. The Summilux at f1.4 is very fine  
but from f2 to f4 the DR lens gives me higher resolution. This is  
caused by a focus shift and back focus at those openings, very  
similar to the shift of the Noctilux, but to a lesser extent.  This  
is probably not a problem at longer distances and especially at  
infinity. I also measure higher resolution when testing with low  
grain, high sharpness film and developers using an M7 or MP body. I  
can never measure resolution above 88 lpmm with the M8 but measure  
100 lpmm with film with the same lens at the same openings. The focus  
shift is also not so obvious. But even though the resolution of the  
DR and Summilux are the same, the Summilux has higher contrast and  
photos taken with it appear sharper.

As a side note, the Noctilux is just as sharp as the Summilux in the  
f5.6 to f11 openings. Some of the Luggers know this and take  
advantage of it and treat the Noctilux as a normal lens.

Note: This is what a retired engineer enjoys doing on rainy days when  
he's not out taking pictures of birds, flowers or landscapes.

Len


On Aug 30, 2008, at 1:58 AM, Peter Klein wrote:

> Lee:  The DR has very high resolution, and also moderate contrast.   
> The latter might be a good thing for digital. Really bright  
> highlights tend to bleed slightly into their darker surroundings,  
> which sounds like a defect but actually looks very nice in practice.
>
> This is different from the Summilux ASPH, which is a modern lens  
> with biting sharpness--high contrast as well as resolution.   
> Completely different personality.  My guess is that you might  
> prefer it over the DR for aerial photography.
>
> My take is that one doesn't use a DR for its resolution so much as  
> one uses it for its look.
>
> The DR was my favorite outdoor lens with film, and I intend to use  
> mine on my M8 when it comes back from its "operation" at DAG.
>
> Hope this is useful.
>
> --Peter
>
>
> _______________________________________________
> Leica Users Group.
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Replies: Reply from kididdoc at cox.net (Steve Barbour) ([Leica] question to Steve Barbour concerning dual range summicron)
In reply to: Message from pklein at threshinc.com (Peter Klein) ([Leica] question to Steve Barbour concerning dual range summicron)