RustyBug wrote:
bjhurley wrote
RustyBug wrote
How's the focus shift? How do you contend with it ... or, do you mostly shoot wide open with it? Is there a point at which the DOF (stopping down) offsets the focus shift? I've started using this lens on film, and while the focus shift is certainly an issue to contend with it's not a dealbreaker (for me, anyway).
My understanding is that the recent versions of this lens are calibrated by Cosina at f2, not wide open, so I mainly use the lens at f2 if I want shallow depth of field; I've found I can use f5.6 and above safely as the greater depth of field compensates for the focus shift. It's really just at 1.5 and between f2.8 and f4 that you can run into trouble; on film this is less of an issue since 35mm film is pretty low-resolution to begin with and slight misfocus is less obvious than it would be with digital.
If you don't want to recalibrate the lens to 1.5 but want to be able to shoot 1.5 occasionally, you could figure out through trial and error how much you need to compensate for what the rangefinder is suggesting is in focus but it'll always be imprecise unless you're using a digital rangefinder with liveview. In my case, on film I just don't use it wide open; I'm quite happy with it at f2 anyway. My Leica film camera came with a dual-range Summicron, also an f2 lens, but it's considerably heavier and larger than the C-Sonnar. Gotcha.
I guess I could mount the Visoflex or use LCD LiveView ... either for shooting, or for "mental calibration" of where to land the RF patch.
Just as an "odd question" ... could (not saying would) the lens be re-calibrated to f/2.8 or f/4, or even f/5.6 if someone wanted to do such an "odd" thing?
I had my ZM Sonnar 50/1.5 recalibrated by DAG years ago. At the time, he gave me the choice of recalibrating it at either f/1.5 or at f/2.8. I was told that the lens was cerebrated at f/2.8 out of factory when purchased new. So I believe it can be done at f/2.8. At f/4, the focus shit may not have that big of an effect.