Back focus or rangefinder alignment?

[jmarcus]

Is back focus exclusive to lens adjustment?

I focused on the guy on the left, his eyeball. As you can see the guy on the right is in focus.

thanks,
James

[jmarcus]

Shot with a Voigtlander 50mm f/1.5 at 1.5

[Catto]

Funny, I've been asking myself the same question about my 50mm f/1.5 on an R-D1s - new (to me) camera, brand new lens, very hard to be sure.

But, I'm reserving judgement on mine, and on this particular image, because I can't be totally sure that I or my subjects (or you & yours, not having been there) didn't move ever so slightly and miss the focus that way. 1.5 is pretty slim DOF, of course - esp. to get two people together sharp on the same plane, I see it all the time with my Canon gear & the 85 1.2. If either you or they shifted a little, even just rebalancing your weight on your feet, that could be enough for what you're seeing in that image.

I think the only way to eliminate the rangefinder alignment question is to check other lenses on your body, and / or that lens on another body, and see if your RF is consistently out with all of them; or if that lens is consistently out with many cameras. Which can be tricky, if there aren't other R-D1s around...

Try shooting some non-moving subjects with the camera on a tripod, and see if you can pin down the problem that way; at least that will tell you if the lens / body combo is wrong, or if it was actually some movement on the night in that particular case.

Hope that helps?
R

[jmarcus]

I have three other pictures with the same focus, so I don't think its movement. The problem with different lenses is that I don't have another 1.5, just a 2.0 and a 2.8

James

[Catto]

Had another thought this morning, but can't remember where I was reading it - there was a theory being put forward that the direction of rotation you use to achieve focus may, due to play / slop in the focus mechanism of any manual focus lens, mean there was a certain amount of inaccuracy or loss of sharpness.

They were suggesting that you test your lenses by coming towards the point of sharp focus from infinity, and from min. focus distance, to determine which direction gave more accurate results for your particular combination of lens / rangefinder alignment, and this was probably recommended for all your lenses individually.

Personally...it's all a bit hard. Unless I find a huge problem, I can't be arsed doing all that! Up to you whether it's worth testing in this particular case.
R