I won’t go into detail about just how the MS Optical Sonnetar 50mm f/1.1 in Leica M mount came into my use; suffice to say it involved a hat, some rare film and Bellamy over at Japan Camera Hunter. You can see and read about this unique lens over at Bellamy’s excellent site
What this post will do is show just what I think that rear coma adjustment is doing.
The MS Optical Sonnetar 50mm f/1.1 at f/1.4, setting at Red Dot.
This is a full frame scan from a tripod mounted Leica M4, cable release, shot on Kodak Tmax 100 processed in DK:50 1:1 (if you want to argue about the resolution of TMX in DK-50 vs XTOL or Rodinal let me hear it and that might be another blog post, if you don’t then just accept that DK-50 1:1 is sharp enough for this intended purpose).
Focus was on the left of center flower, at 1.2 meter setting on the lens. Each frame after coma adjustment was re-focused on the same left of center flower.
Now look at a set of cropped scans of the above, with frames following with the coma setting at full front and full back settings.
Red Dot setting.
Coma Setting at Full Front
Coma setting at Full Back
As can be expected, the creator and optical genius Mr. Miyazaki is correct in his “suggestion” that the Red Dot setting is the best for all around use; the flower that I focussed on is sharp and the bokeh of the background is smooth and cohesively interesting.
Moving the coma setting to full front caused the flower to move slightly out of focus towards the rear, but also cleaned up the bokeh of the keyboard and chair back.
Moving the coma setting to full back caused the flower to move slightly out of focus towards the front, but also creamed out the bokeh of the keyboard and chair back.
When I did my standard lens test from 15 feet/ 5 meters away, tripod cable release all apertures etc, I found that at and near wide open it wasn’t that great of a 50mm lens. It was pretty sharp in the middle but it needed to get to at least f/ 4 to start to clean up the areas near the edges, and the lens looked decent at about f/8-11. This was done at the Red Dot setting, and I suspect that if I adjusted the coma setting to the front, at landscape and ‘environmental’ focussing distances the lens would be very sharp at wider f-stops. (I will have to test this!) As it stands, moving the coma adjustment settings to the rear seems to correct nicely for the focus shift inherent in the Sonnar optical design, while adding even more character to the bokeh.
These findings are consistent with the known focus shift challenges of the Sonnar design, and to me represent a creative and adjustable solution. I would strongly suggest examining and comparing this lens to the Carl Zeiss C Sonnar 50mm f/1.5, which is one my favorite 50mm lenses.
A few side notes about this interesting lens. The f-stop adjustment is way way too easy to shift. A firm click stop is my suggestion. The focussing peg is ok if you can remember to use it instead of moving the f-stop ring. I think either a actual focussing ring or a Leica-like tab would be more useful to me personally. The hood is too small, but the filter thread is 52mm which makes using neutral density filters much easier for me and I just end up using a Nikon 52mm hood for 50mm lens. The excellent multi-coating looks fantastic and is very durable and easy to clean. It reminds me of Nikon’s SIC in the late 1970’s-1980’s.
Special Thanks to Cory Lum and of course, Bellamy of Japan Camera Hunters.
The MS Optical Sonnetar 50mm f/1.1 at f/1.4, setting at Red Dot.
Crystal on one of my last rolls of Fuji Neopan 1600; processed in replenished Xtol.
