Anybody doing lens conversion (M42 to M mount)?

[darkosaric]

Friend of mine has a dream: Helios 58mm f2 with M mount, with focusing. I know there are adapters, but no focus there. I know one can use M42 camera, but he asked me if this conversion is possible.

So if someone knows where this conversion with focus on Leica can be done - please write.

Thanks!

 

[film_man]

There's a guy who does some special stuff but mainly in medium format, maybe he can help, maybe he knows someone who can help, look up The Bokeh Factory. Not cheap though.

 

[Nitroplait]

Why spend more on the conversion than the cost of a Leica Elmar 50mm, when he can get a beautiful classic Pentax Spotmatic for pennies which will work plug and play?

 

[Oren Grad]

I know there are adapters, but no focus there.

There was a Japanese manufacturer that offered sort-of-coupled M adapters for selected SLR lens mounts. The adapter itself coupled to the RF; you focused the adapter, read the distance off of the adapter's distance scale and transferred the setting to the helical of the SLR lens. However, these were offered only briefly and would likely be difficult to find on the used market.

Stephen Gandy offered these adapters when they were available:

https://web.archive.org/web/20050203215552/http://cameraquest.com/adaptslrRFM.htm

 

[darkosaric]

Those adapters are great solution, but 325$ is a pretty high price. But I guess it is like that when you have very specific wish. The less people wants something - and you want it - you need to pay more.

 

[reddesert]

I think one would need access to the individual lens to make an accurate rangefinder-cam conversion, to cope with variations in lens focal length between individual specimens. If you're trying to focus a f/2 lens wide open and the circle of confusion is 0.03 mm, you need to position the lens forward/back within 0.06mm, ideally better. That is certainly doable with a lens and its native focusing system (SLR or RF), but I expect that the variance in focal length between lenses is bigger than 0.06mm; one reason that RF lenses often have shims or means of adjusting the RF cam.

The RF adapters linked by Oren are cute, but if you look at for example the focus numbers vs the DOF scale of the Olympus 40mm lens they show, it looks like the method of matching the focus scales would be hard to be accurate enough to focus f/2 well. (Plus, I expect the focus scales on most lenses are approximate, not compensated for variations in focal length.)