Rangefinder Patches Off a Bit

[Clickie McPete]

I've been collecting rangefinder cameras for the past year and in that time have amassed quite a few. Some of these cameras are very finely made such as the Bessa R3A, Bessa 667 Hasselblad X Pan, Olympus RD, Konica C35 FD, Konica S3 Auto and many others. It's been a blast finding these things and in some cases getting them restored.

What I'm wondering is this: How come the rangefinders become out of alignment?

Now, I have had some adjusted and they are close to perfect now but invariably I find when I set them to infinite, they are usually slightly better aligned if you back off a tiny tiny amount from all the way over. Even a brand new R3A from Stephan Gandy was like this as was my Leica M8. Does this make sense? What is the acceptable amount of rangefinder patch misalignment for these cameras to be considered in alignment? The older 1970's cameras will often be off vertically if not horizontally as well.

My feeling is that these are really meant to be a more accurate version of the older zone focus. In other words, if you are close to alignment then depth of field, especially when the subject is at a distance, will take care of it and everything will be in focus just fine. So the theory is that this type of focus system gets you close enough and not to worry about perfect alignment of every image unless you're doing portraits.

 

[katgut@earthlink.net]

If you've ever seen a schematic of a rangefinder system, you've seen how hideously complex they are. Given the precision needed with different lenses (if an interchangeable system), and the focusing quirks of each of those lenses, they do pretty well. It depends on what level of accuracy you expect.

My Mamiya 6 is extremely accurate, and I routinely shoot my 150 wide-open. I wouldn't be surprised if temperature variations can cause misalignment. My M4-p focuses accurately with a 90 f2 wide-open as well.
Even SLRs can suffer from problems, and every link in the focus chain can cause problems. As an average, more of my rangefinder images are better focused than those from my Canon F-1.

I was told by a supposed Leica repairman that older models such as the M4 had hand-matched components in their viewfinder assembly, but later models such as the M6 did not stick to such precision, leading to a higher degree of rangefinder misalignment (and the inability to achieve exact alignment).

 

[Clickie McPete]

Thanks for those insights.