Front Focus & Two 35mm Summicrons
A little more about the front focus problem that some R-D1 users have been experiencing with some lenses.
The rangefinder on my R-D1 is perfectly aligned and I have tested the focusing accuracy with the following rangefinder coupled lenses: My 35mm f/2 Summicron, 50mm f/2 Summicron, 90 f/2.8 Tele-Elmarit. Plus a friends VC 28mm f/3.5, 40mm f/1.4 and 75mm f/2.5. The only lens that does not achieve accurate focus is my 35mm f/2 Summicron, Leitz Canada about 1975 vintage and owned from new. This at distance of about 5 feet and at full aperture shows a front focus of about 3 inches.
On Thurday I was with another friend who also has a 35mm Summicron f/2, again Leitz Canada but of a later vintage than mine, he thinks about 1985. I took the oportunity to try his lens on my R-D1 to see how the focusing compared.
Attached are 100% crops from both lenses shot at full aperture - f/2.0. Number 1 mine, Number 2 his. The point focused on (at a distance of about 5 feet) is marked FP. The point where I see best focus in these photos is marked SP (sharp point) and is very slightly different for both lenses. You will first notice that his lens seems quite a bit sharper and a little more contrasty, but BOTH seem to front focus by about the same amount, just over 3 inches.
This you will note was not a totally controlled test as both were not Raw but H jpegs straight from the camera. There was no further adjustments, iso was set at 400 and the camera was handheld - shutter speed was about 1/112 in both cases. I would think that it does at least represent some 'real world' conditions of use.
As the lenses achieve accurate focus both on my M4 and his M6, I can only assume that the issue comes down to incompatibility with the cams and the R-D1's focus wheel with certain vintages\factories. It would be interesting to know if other R-D1 owners who also have a 35mm f/2 Summicron have a problem with this lens.
Last edited by Jim Watts : 02-19-2005 at 07:43.