I’m a 50mm guy. The two in this article, the 3rd gen Summicron-M, and a Summilux-M ASPH, are favourites of mine for for vastly different reasons:
1- The Summicron is tiny, sharp, has a long focus throw, and soft-highlighted out of focus rendition with a bit of swirl.
2- The Summilux sports the most iconic modern typography, and despite being cylindrical, is drop-dead sexy.
The Summilux is, by all objective measures of sharpness, corner shading, colour contrast, etc., the better lens. Still, I decided to stage a sharpness play between it and the V3 Summicron. And, in casting, and performing this shindig, I realised that I am not qualified to make sharpness comparisons. Firstly, the images in this article were shot at 1 metre (measured), a distancing approximating the close focus for a majority of 50mm Leica rangefinder lenses, and subject to the slightest misalignment of subject and media planes. Being a macro photographer with the side hobby of shooting architecture, I knew this. I knew that I would fail to conduct an objective comparison. But
Nevertheless, I thought I would pit my favourite, the Summicron, with a lens whose dead sexiness keeps me from parting with it. And, I thought I’d show my support for the great table top game, Carcassonne, in the process. The full image is below:
Note: the following images were taken on an M240, and thrice focus-checked via the add-on EVF. I used a cable release. The camera was mounted to an Arca Swiss Cube and that to a 3-series carbon-fibre Gitzo tripod. Summicron images appear on the left, Summilux images on the right.
As far as I see it, there are only two conclusions you can draw from the above maladroit comparo: 1. that the focal plane and subjects most likely were misaligned; 2. that one or the other lens’s planar sharpness is limited by field curvature. Or, both and perhaps something I didn’t see. Despite the rigorous attendance to measurements and alignment my day job requires, the equipment I have and what patience I possess are not up to the task of comparing sharpness at close focus distances between two fast lenses.
Subjectively, and with attention paid to the centre of the image, I can say that despite my tests, the Summilux shows superior sharpness. It is also obvious that in large part, that advantage evaporates by F4.
I have another question: do either absolute or planar sharpness even matter? When focusing a lens either manually or automatically, you are working against acceptable levels of focus aberration, calculation errors, and user error, not to mention the point at which not sharp becomes good enough. As to the importance of left-to-right planar sharpness, it is my firm conviction that it is field irrelevant. That is, unless you do reproduction work. But if that is your job, you are likely using enlarging or reproduction lenses on reproduction cameras. Certainly you are not reading sites like this one.
ohm image: Nagano, Japan: through the Summicron 50