I am looking to buy the C-Sonnar soon (once a store actually has one in stock or one becomes available on this forum) but I have one (probably so obvious bordering on stupid) question regarding optimisation for this lens.
Can I assume that if it is optimised for f1.5 that it is optimised for the film cameras like the Ikon or M2/3/4/6/7/P and not for digital rangefinders like the RD1 and M8/9?
Thanks
I have the old Sonnar (Opton) as well as the new C-Sonnar too (both in black and chrome).
All 50mm Sonnar designs, new or old, exhibit focus shift due to residual spherical aberrations; so does the Summilux 50 pre, Summilux 35 pre, Summilux 35 Asph. v.1, even the latest formula Summicron 50 (just a little bit; see my post related to Focus-Shift.)
The C-Sonnars used to come out of the factory optimized for f2.8, the later production was for f1.5. Assuming you would buy the later production, you would notice the focus shift at
close distances moving to backward of the plane you focused @f1.5 as you stop down to say f4.. How much? Just about two inches. How to take care of it: If you shoot f1.5- f2 then don't mind.. if you shoot f2.8 or f4 then try to focus just couple of centimeters behind the point of your actual focus. Example: Shooting at f1.5 or f2; distance about 1m, focus on the eyes you will get the eyes sharp. Shooting at f2.8 or f4; distance again about 1m, focus on the ears you will get the eyes sharp. (Or focus on the eyes first and then move your head two inches backward before pressing the shutter.)
Anything beyond 2m of focus, do not mind, it will be within the DOF. Anything to be shot f5.6 or smaller at any distance then do not mind again.
These are for ANY M-mount, be it for film or digital. On the Liveview bodies like NEX, m43, etc., you see where you focus so it is no issue at all.
I have various 50mm Leica lenses and the C-Sonnar too. Sonnar is my favorite 50; using it on the M-bodies as well as on the Nex. It has a different signature than all other 50mm lenses I use.