Hello,
I was wondering how the Jupiter 6 differs from the rangefinder-coupled 180 sonnar?
Specifically, I wondered if the focusing helical was a direct copy in terms of the pitch - or even if any of the non-coupling Sonnars have the same focus helical?
I'm hoping it might be practically possible to remove a Jupiter 6 M39/M42 mount, then graft on a Jupiter 11 mount (with the internal coupling part). If the focusing helical appears to be the same then it should theoretically be much easier.
Jonathan
Hi Jonathan,
As someone who has long desired the mythical and elusive rangefinder coupled 18cm Olympia I find this a fascinating idea indeed. I wish you well.
I think I actually understand what it is you propose to do. No—of course you can't utilise the helicals out of a 135mm lens to make a 180mm lens focus on a Contax—but, I get it. You only want the mount and collar that couples it to the inner bayonet (Ie rangefinder) to graft on.
Perhaps I've missed it (I did re-read the thread a couple of times, nevertheless). What Contax will you use this with if it can work? I suspect you're well aware of this but in the interests of clarity, if only for other readers, I'll be explicit—only a Contax II or III (well, maybe a Kiev, a really good one, that is) will be viable—no other will suffice. Certainly not the Contax IIa or IIIa with their inferior rangefinder installations.
I will offer a few general observations.
What you really need is a bit of hard data about the focus characteristics of the original Sonnars. A good start would be the precise distance each version is focused to with its focus ring rotated 90° and 180° respectively from their infinity stops.
If you use Facebook
this is the group you need to consult. There are one or two members who actually own RF coupled Olympias, for starters. And some who have the Flektoscop versions, too.
I've taken the liberty of asking Ira Cohen if he knows whether or not the focus was altered. Ira owns a coupled Olympia.
My own suspicions are that the helicals weren't altered. Why?
Everybody with an interest in them knows the coupled Olympia is rare. Vanishingly rare. That's no news. Yes, part of the reason is few were made (150-odd?).
But what makes them even rarer is that according to sources I've read many of those coupled lenses were subsequently converted to reflex mount—making original specification, un-modified, coupled specimens, real unicorns.
Now: if conversion dictated substituting not only the rear mounting but the inner and outer helicals and the focus ring that drives them (because if the helicals were different, and, hence, the rate of focus per degree of ring rotation was not the same, the original ring scale is toast, right?), then—all you're really left to re-purpose is the glass itself, their mounts, and maybe the front bezel and a few other minor bits. Ain't going to happen, I reckon. Hence, I suspect the converted reflex versions must have kept the same helicals and ring, surely? (If not—there would have to be early and later versions, with different focus throws).
Ignoring that for the moment—if you can get data on degrees of focus ring rotation to scale distance shown for the coupled version, at least—all you'll need to do is compare these to the same info for the Jupiter. If they match—you could be good.
I wouldn't be as pessimistic about the possibility of focusing the 18cm by rangefinder. Sure—it will be testing to nail focus wide open at the middle distance. But who among us has seen images made with such a combination at different distances, and apertures, tripod mounted, and painstakingly focused, to really know for sure? I certainly haven't (although I'd love to do some!).
Also, few people—even rangefinder camera geeks—truly understand just how phenomenally precise the II/III rangefinders are. (And no, I'm
not just talking about effective bloody base length, either, it's a source of no little frustration to me that even here, at Rangefinder Forum, there's a perennial lack of interest in delving any deeper into the specifics of RF accuracy than good old "EBL". There's a great deal more to it, than just that, two different rangefinders with identical EBLs can have quite differing levels of precision).
You may need to mark, strip, lubricate and re-assemble your rangefinder system. No doubt it's still factory perfect in its calibration but it will still have to be moving freely and in as-new condition, for it to handle the Olympia—but I reckon it can do it. Goes without saying the body helical will also want to be clean, lubricated, and absolutely tip top, as well as the lens register (body back focus and parallelism).
Of course, you do realise that—should you pull this off—you're in danger of being asked to do a second such conversion, for me?
😉
Please, keep me in the loop.
Cheers
Brett
