jgrainger
Established
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
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
Cascadilla
Well-known
I'd be very surprised if a mount for a 135 lens would bring a 180 lens into focus properly. Zeiss gave up fairly quickly on the 180 f/2.8 Sonnar focusing accurately on the Contax II/III bodies and went with a reflex housing since the Contax rangefinder, good as it is, wasn't up to the task of focusing a 180 f/2.8 lens wide open. In any use, the 180 f/2.8 is a lot bigger than the fairly slim 135 f/4 lens so adapting it would seem to be difficult at best. I've had good results from a 180 f/6.3 Tele Tessar K with a Contax III, but I haven't used it at full aperture.
View Range
Well-known
For a given focal length, all lenses of that focal length must move the same amount to achieve focus at a particular distance. The movement amount is different for each focal length; the shorter the focal length, the smaller the movement. (This is not true for lenses with internal focus which does not apply to Contax.)
jgrainger
Established
My original post is asking about the focusing helical in the original Contax 180 Sonnar vs the Jupiter 6 which is apparently more or less a copy. I wouldn't try to use that part from a Jupiter 11.. re-reading, it isn't all very clear.
To be fair, there's also some assumption on my part, that the rangefinder coupled 180 Sonnar would have the same helical as the non-coupled variant which was probably copied.
If the Jupiter 6 has a copied helical from the Sonnar then I'd hope it may be possible to use that helical, lens elements, housing, and diaphragm.. combined with basically only the outer bayonet mount, and part of the inner coupling device from the Jupiter 11 - grafting them together. This would seem a possible way to do such a conversion while not having to produce a custom focusing helical.
I've also looked at the theoretical DOF and focusing accuracy of the camera's rangefinder, it looks to be possible to focus at 2.8 depending on whether the object in view has something suitable to focus on - I'd not really be looking to go beyond f4 or 5.6 though.
The 180 Tessar is a nice option but they're not cheap/ unlikely to be coated/ not a lot of sample images/ why not just go for it and try to adapt a Jupiter 6
- I'm a part-time machinist and my hobbies include watch repair, so making parts isn't really a deal breaker.. except for the helical which wouldn't really be practical to produce on my own or even work's machines (time/unusual TPI).
To be fair, there's also some assumption on my part, that the rangefinder coupled 180 Sonnar would have the same helical as the non-coupled variant which was probably copied.
If the Jupiter 6 has a copied helical from the Sonnar then I'd hope it may be possible to use that helical, lens elements, housing, and diaphragm.. combined with basically only the outer bayonet mount, and part of the inner coupling device from the Jupiter 11 - grafting them together. This would seem a possible way to do such a conversion while not having to produce a custom focusing helical.
I've also looked at the theoretical DOF and focusing accuracy of the camera's rangefinder, it looks to be possible to focus at 2.8 depending on whether the object in view has something suitable to focus on - I'd not really be looking to go beyond f4 or 5.6 though.
The 180 Tessar is a nice option but they're not cheap/ unlikely to be coated/ not a lot of sample images/ why not just go for it and try to adapt a Jupiter 6
- I'm a part-time machinist and my hobbies include watch repair, so making parts isn't really a deal breaker.. except for the helical which wouldn't really be practical to produce on my own or even work's machines (time/unusual TPI).
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Phil_F_NM
Camera hacker
About a decade ago, I had a Komura 200mm f/4.5 which was a rangefinder coupled L39 lens. I don't think I ever tried to use it on my M4 because it was extremely difficult to focus accurately. I had an M8 or M9 at the time and found the depth of field was too narrow, the helical thread lash became apparent, and the mechanical linkage between camera and lens not precise enough. It can't be made precise enough either.
I think this project is an admirable challenge just to do it, but without a camera with live view, like a newer Leica digital, will make shooting with this lens all but impossible.
Phil Forrest
I think this project is an admirable challenge just to do it, but without a camera with live view, like a newer Leica digital, will make shooting with this lens all but impossible.
Phil Forrest
Scrambler
Well-known
This sounds like a never-before-asked question.
I think your best estimation will be the distance marks on the barrel, comparing the lenses. What distance for a 90 degree turn? If not the same, pitch is different.
The Soviet engineers seem to have had the approach of "ain't broke, don't fix" so there's a good chance.
But the only true test will be the mount you propose.
Good luck!
I think your best estimation will be the distance marks on the barrel, comparing the lenses. What distance for a 90 degree turn? If not the same, pitch is different.
The Soviet engineers seem to have had the approach of "ain't broke, don't fix" so there's a good chance.
But the only true test will be the mount you propose.
Good luck!
jgrainger
Established
Phil,
I'd forgotten about the Komura lens.. the accuracy of the Contax should be just sufficient but challenging at the wider apertures. Realistically there are adaptors for the contax mount, so it could still be possible to use the said lens on something else using live view.
Scrambler,
Thats exactly what I was thinking for checking the helicals, but I don't have either lens to compare (hoping someone here might).. I've looked at pictures online but it's not an ideal situation - though likely the lens was just literally copied or continued like the rest of the Contax stuff vs the Soviets not using the leica standard.
There's actually a rough Hassy Zeiss 180 for a low price but that would be less likely to be still in pre-war spec..
Will keep looking at pictures and make a decision this next week
I'd forgotten about the Komura lens.. the accuracy of the Contax should be just sufficient but challenging at the wider apertures. Realistically there are adaptors for the contax mount, so it could still be possible to use the said lens on something else using live view.
Scrambler,
Thats exactly what I was thinking for checking the helicals, but I don't have either lens to compare (hoping someone here might).. I've looked at pictures online but it's not an ideal situation - though likely the lens was just literally copied or continued like the rest of the Contax stuff vs the Soviets not using the leica standard.
There's actually a rough Hassy Zeiss 180 for a low price but that would be less likely to be still in pre-war spec..
Will keep looking at pictures and make a decision this next week
Elmar Lang
Well-known
Does a Jupiter-6 180/2,8 exist with Contax/Kiev Bayonet?... Mine's with 42x1 screw.
Malcolm M
Well-known
I assume that the lens you are proposing to use was intended for SLR use. To get it to work on a Contax rangefinder, you would need a short extension tube to match the flange-film distance on the camera to that which the lens was designed for, and then provide a focussing cam so that the movement at the rear of the lens matched that of the (5cm) lens for which the rangefinder is calibrated. Give up NOW!
Huh?
Where is this rear focusing cam? I can't find it in my Contaxes (or their lenses).
RF coupling accuracy (for any of the lenses with their own helicals) hinges on the degree of parity between those helicals and the body helical that actually drives the rangefinder—by gear—not by cam.
jgrainger
Established
Elmar, I don't think a Contax / Kiev coupled Jupiter 6 exists..
Do you know how many degrees of focus rotation your example has (from minimum marked distance to infinity), and the minimum marked distance that rotation goes from?
- this is key to figuring out whether the Jupiter 6 helical would match a Contax in terms of tracking distance at the same rate as the rangefinder mount rotates over it's distance.
Malcolm, it would be a SLR lens.. machining and adapting the mounting parts wouldn't be too bad - but only if the helical matches a RF coupled Sonnar..
As Sarcophilus says, there's no focusing cam on Contax lenses - it's the main reason that the Jupiter 6 helical is so important for this potential conversion, rather than spending some time being able to make and adjust a cam ring for an LTM lens conversion.
Do you know how many degrees of focus rotation your example has (from minimum marked distance to infinity), and the minimum marked distance that rotation goes from?
- this is key to figuring out whether the Jupiter 6 helical would match a Contax in terms of tracking distance at the same rate as the rangefinder mount rotates over it's distance.
Malcolm, it would be a SLR lens.. machining and adapting the mounting parts wouldn't be too bad - but only if the helical matches a RF coupled Sonnar..
As Sarcophilus says, there's no focusing cam on Contax lenses - it's the main reason that the Jupiter 6 helical is so important for this potential conversion, rather than spending some time being able to make and adjust a cam ring for an LTM lens conversion.
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
jgrainger
Established
Brett,
That's basically my thoughts on this..
The pre-war Contax and Kievs look to have the same CTC distance between the rangefinder and viewfinder as a Koni Omega (which can mount a slower 180mm), though the magnification and size of viewfinder is different.. as you say, EBL (or even the physical size) isn't the whole picture.
I looked up the DOF for a 180mm Sonnar at 2m then looked through the rangefinder of a III at the same distance on some items with 5-15mm difference in distance to see whether it looked to be good enough to fall within the central half of the theoretical DOF.. My conclusion was that it would be easy to mess up through a poorly matched lens to body or if rushing, etc, but doable with some care..
I'm mostly concerned about any backlash in the gears of the system, of which there is a slight amount at the camera helical.. your comments about servicing the focusing parts of the camera seems especially valid (I've cleaned the helical, viewfinder, prism, but not actually tried disassembling the parts which the pivoted lens is attached to - for fear of being the first person to mess up an otherwise reliable system).
I've received a 1960 Jupiter 11 and comparing it to a late CZ 135 Sonnar the parts are of a looser fit.. but could probably be tightened up a bit.
In terms of the liklihood that the helical was changed..
It doesn't seem beneficial to change it for an early SLR which doesn't care about the rate of throw (back before it became a thing). As the tooling, examples to copy, and design philosophy would have been somewhat carried over (as evident in other Jupiter Contax-based lenses / relocation of technicians etc after the war), I think it's pretty likely that the Jupiter Helical is the same pitch as the coupled Sonnar, and that the coupled and non-coupled Sonnar are the same..
Your suggestion of the 90 and 180 degree test is probably much easier than my proposed measurement of the total rotation to mimimum marked distance method.
Thank you for asking Ira Cohen, I'll check the facebook group when next on - trying to have some time off it at present.
If I do go ahead with this and pull it off, chances are that it'll be a labour of love to actually complete, but shall see how it looks and go from there.. must admit I was more hoping to try to eventually make a name for myself through watchmaking or by learning to service the Contaflex and Contax better than most.. but would consider trying to make a couple of these.
That's basically my thoughts on this..
The pre-war Contax and Kievs look to have the same CTC distance between the rangefinder and viewfinder as a Koni Omega (which can mount a slower 180mm), though the magnification and size of viewfinder is different.. as you say, EBL (or even the physical size) isn't the whole picture.
I looked up the DOF for a 180mm Sonnar at 2m then looked through the rangefinder of a III at the same distance on some items with 5-15mm difference in distance to see whether it looked to be good enough to fall within the central half of the theoretical DOF.. My conclusion was that it would be easy to mess up through a poorly matched lens to body or if rushing, etc, but doable with some care..
I'm mostly concerned about any backlash in the gears of the system, of which there is a slight amount at the camera helical.. your comments about servicing the focusing parts of the camera seems especially valid (I've cleaned the helical, viewfinder, prism, but not actually tried disassembling the parts which the pivoted lens is attached to - for fear of being the first person to mess up an otherwise reliable system).
I've received a 1960 Jupiter 11 and comparing it to a late CZ 135 Sonnar the parts are of a looser fit.. but could probably be tightened up a bit.
In terms of the liklihood that the helical was changed..
It doesn't seem beneficial to change it for an early SLR which doesn't care about the rate of throw (back before it became a thing). As the tooling, examples to copy, and design philosophy would have been somewhat carried over (as evident in other Jupiter Contax-based lenses / relocation of technicians etc after the war), I think it's pretty likely that the Jupiter Helical is the same pitch as the coupled Sonnar, and that the coupled and non-coupled Sonnar are the same..
Your suggestion of the 90 and 180 degree test is probably much easier than my proposed measurement of the total rotation to mimimum marked distance method.
Thank you for asking Ira Cohen, I'll check the facebook group when next on - trying to have some time off it at present.
If I do go ahead with this and pull it off, chances are that it'll be a labour of love to actually complete, but shall see how it looks and go from there.. must admit I was more hoping to try to eventually make a name for myself through watchmaking or by learning to service the Contaflex and Contax better than most.. but would consider trying to make a couple of these.
jgrainger
Established
I recently realised that the 85mm and 135mm lenses (and all other Contax rangefinder lenses could be compared to the Jupiter 6 lenses, and the older 180mm Sonnar lenses.
I've concluded that the silver Jupiter 6 lenses I've seen do not appear to have a suitable helical, nor do some seemingly older black J6 lenses (though a specific variant of J6 do appear to be rather close to one of the Jena 180mm Sonnar variants).
One of the early Jena variants looked appealing but will also not work.
There are two problems, the helical needs to focus to the same distance as the shorter lenses, when turned 90 degrees, and it must also rotate in the correct direction.
I'll keep looking at different variants and see if there's another work-around.
I've concluded that the silver Jupiter 6 lenses I've seen do not appear to have a suitable helical, nor do some seemingly older black J6 lenses (though a specific variant of J6 do appear to be rather close to one of the Jena 180mm Sonnar variants).
One of the early Jena variants looked appealing but will also not work.
There are two problems, the helical needs to focus to the same distance as the shorter lenses, when turned 90 degrees, and it must also rotate in the correct direction.
I'll keep looking at different variants and see if there's another work-around.
Malcolm M
Well-known
Jonathan- if you're looking for a 180mm rangefinder coupled lens for Contax, rather than the Olympic Sonnar specifically, MW Classic have an f6.3 version.
https://www.mwclassic.com/product/c...rnal-mount-usually-found-with-external-mount/
https://www.mwclassic.com/product/c...rnal-mount-usually-found-with-external-mount/
Cascadilla
Well-known
I can't imagine that an internal mount for this lens would be a good idea--my external mount version is fairly heavy, and front heavy at that.
jgrainger
Established
Malcolm,
The 180mm tessar is a good practical suggestion.. I don't really need a 180mm lens, but would like an olympia sonnar or copy - perhaos more GAS than practical necessity.
Cascadilla,
The 180mm lenses for the Contax (though the Sonnar in particular) all look like things the camera is fitted to, rather than the lens being the fitted part.
The 180mm tessar is a good practical suggestion.. I don't really need a 180mm lens, but would like an olympia sonnar or copy - perhaos more GAS than practical necessity.
Cascadilla,
The 180mm lenses for the Contax (though the Sonnar in particular) all look like things the camera is fitted to, rather than the lens being the fitted part.
Cascadilla
Well-known
I've actually had pretty good results from my 180 Tessar hand held at 1/250 or 1/500. I'm holding the camera body as well as the lens for this and the camera body feels fine--better than I would have expected. If I am going to haul a tripod around I would use a bigger camera than a Contax. I've never had the opportunity to see a 180 f/2.8 Sonnar in the flesh, but I suspect it would be a lot like my heavy 80-200 f/2.8 zoom on my DSLR. I can hand hold that lens, but not for long.