kiev internal focusing system

[timmyd18]

Hello! After all the recent Kiev hubub, I decided I needed to get one. So i found a very cheap 4AM with a Helios 103 and I also got a 1958 Jupiter 12. I'd get a nicer Kiev but I can't really afford one.

I'm very happy with the camera and both lenses. I think i like the ergonomics and being able to one-hand it. I hope to be using it very often in the future.

I just have one question- this internal focusing mechanism for 50mm lenses really puzzles me. Can anyone tell me what the advantage was for building this into the camera instead of the lens? It seems like it makes the camera more complicated to me, but I'm sure there's a good reason for it

thanks

tim

 

[Ed S.]

My Guess

My Guess

Go to the Kiev Survival site (Lenses) and look at the J-9, J-11 and J-12 disassembly photos. These lenses are similar to SLR lenses; they have a focusing ring and the lens base mounts on to the camera body mount, but only rotates, it does not move in or out.

Note that the helical threads or slots in the lens assemblies have different pitches. This provides the translation mechanism between the rangefinder and any of the different focal length lenses.

The 50mm lenses fit into the lens mount on the camera, which has its own helical.

The coupling mechanism to the rangefinder (see this Kiev Survival Site page) then can be essentially some gears and a follower arm that adjusts the rangefinder based on the lens position. When the rangefinder indicates focus on an object, the lens is focused on that object.

This looks to me like the Contax engineers created a design that’s reasonably economical to build: 1) a generic rangefinder design, 2) a generic coupling mechanism, and 3) standard lenses with a common mount design, but custom helicals. Actually, it looks like only the 50mm design was originally intended; the rest might have been an afterthought, when someone realized that there really was a market for additional, interchangeable lenses.

 

[Sonnar Brian]

The interchangeable lenses were planned from the beginning- the external bayonet mount shows that. The Contax design reduces errors that can occur with each lens coupling properly with the RF follower of the body. I've had to put a few layers of copper tape on various Leica style lenses to correct errors on the RF cam.

 

[timmyd18]

thank you both! i think Brian might be on to something- one can see how this would be a reliable way to couple the rangefinder to many different lenses. anyway, there's something satisfying with how it all snaps together.

tim

 

[ruben]

Hi tim,

I think you are asking a very important question to which the only answer you got from Brian doesn't reflect but the fact that most of us, me including, don't know the answer.

Since the prewar Contax design has been the mother of many cameras still in use, and since this design is quite peculiar and sometimes ackward to manipulate, it is of great importance for all to know why things were done such way and not another.

From this knowledge, that I repeat I wish I would know a bit, we can better decide if we want to become dexterous in the original intention of the designers, or want to make shortcuts of our own. See a recent discussion thread about the infinity lock. In these area of how to manipulate the Contax design, I declare myself a pragmatist. But I would like to be an enlightened pragmatist, not an ignorant one.

Now what I can positively throw into discussion here ? Let's notice that by giving the standard lens the privilege of helical mount only, two related things happen. One is that it is the smoothest to rotate. The second is that it is so smooth that we may term it as the "properly" one for the use of the small focusing wheel. Although we all know the 35mm lens can be mooved too.

Now I have to directly ask Brian, or anyone else with the necessary knowledge:
- Why the 35mm for example was not designed for engaging through the helical only, like the standard lens ?

I suspect that this is somehow related to the lens optics and the film plane, but this is just a wild speculation. I really don't know.

Upon the response we may better understand why only the standard got the privilege, and why therefore two ways of lens mounting had to be designed for a single body.

Cheers,
Ruben

 

[Highway 61]

Tim, Ruben,

Start from the basic optics rules and just consider that each focal length has its own focusing helical pitch progression to get the aimed target properly focused at the image point (optics focus).

http://en.wikipedia.org/wiki/Focus_(optics)

Then the geometric differences brought in by the focal length variations get obvious when you look at how any photo lens focusing ring moves. Just play with your various lenses, from wides to telephotos, and you will quickly get it.

Take a 50mm lens off a Leica-type rangefinder camera and look at its rear rangefinder following cam when you rotate the lens focusing ring.

Then do the same but that time with either a 28mm or a 90mm lens.

See the difference in how those lenses rangefinder following cams move ?

Now think of the Leica-type camera built-in rangefinder pinch roller arm. It has to be built in a very particular way, to behave as an "amplifier", to be able to follow either a lens rangefinder coupling cam making its curse from close-focus to infinity with a short pitch progression (wides) or a very long one (telephoto lenses). Plus, this rangefinder coupling arm has a secondary eccentric adjustment so that the repairmen can adjust the rangefinder for accurate infinity and close-focus distances, which makes it an extreme precision mechanism which will not tolerate the least error.

On the Contax/Kiev/Nikon mount, there is no such adjustment because the interaction between the camera internal focusing helical and the lens itself focusing helical (for any lens other than the 50mm one) makes it for a proper rangefinder alignment from infinity to close-focus and viceversa.

To say it with fewer words : in the Contax/Kiev/Nikon rangefinders, any other lens than the 50mm will have its own focusing helical "driven" by the camera body internal focusing helical so that, once seen from "the rangefinder gears point of view" (sorry for that anthropomorphism) any lens mounted on the camera "is" a 50mm one.

The Nikon-S mount borrows the Leica pinch roller arm (located behind the camera body built-in helical) but this one is then a passive slave of the camera built-in helical, and doesn't come in contact with the lens.

Doing this, Nikon made it for a rangefinder getting easy to adjust either vertically or horizontally from the exterior of the camera chassis by eccentric screws, as if it was a Leica-like camera.

The Contax/Kiev rangefinder assembly is, by construction, practically immune from getting out of alignment, but this can happen nonetheless. In this case, a total dissassembly of the camera is mandatory.

Apples vs oranges... 🙂

 

[Spyderman]

IMO the reason for building something like this in the first place was the patents of Leica.

In the end they not only succeeded in bypassing the Leica patents, but also in making the rangefinder more precise, because the focussed distance is transferred as angle of rotation (Contax, Nikon), instead of extension of the cam (LTM, M lenses). Also the lenses are far simpler to manufacture. Just imagine (or find the repair manual for) Kiev-mount and LTM Jupiter-9 (85/2).

 

[ruben]

Many thanks Highway61

Now I am at work, but if I find some time I would like to ask for some clarifications and conlusions that may follow.

Cheers,
Ruben

 

[Highway 61]

In the end they not only succeeded in bypassing the Leica patents, but also in making the rangefinder more precise, because the focussed distance is transferred as angle of rotation (Contax, Nikon), instead of extension of the cam (LTM, M lenses).

The focusing distance is indeed "transferred as a (gears) rotation angle" on the Contax and their "Kiev" Ukrainian copies, but not on the Nikon rangefinders, which have a Leica-like rangefinder pinch roller mounted on an arm that will extense, but within a linear and always identical way whichever the lens focal length is, because what comes in contact with that pinch roller on the Nikon rangefinders is the rear end of the internal built-in helical.

That helical is a clone of the Contax one but with a slightly different optics registration for "50mm" lenses and thus, a different helix threads pitch.

 

[Spyderman]

The focusing distance is indeed "transferred as a (gears) rotation angle" on the Contax and their "Kiev" Ukrainian copies, but not on the Nikon rangefinders, which have a Leica-like rangefinder pinch roller mounted on an arm that will extense, but within a linear and always identical way whichever the lens focal length is, because what comes in contact with that pinch roller on the Nikon rangefinders is the rear end of the internal built-in helical.

You're right, but the basic principle is the same - focussed distance is transferred by angle of rotation.

The mechanism inside is not that important, because even though it's a roller, the roller rides only on the built in helical and the movement of the arm with roller is always proportional to the angle of rotation of the built in helical... so it's as if you had a Leica optimized for one lens, and you never changed that lens.

PS: Now that I've read your post 2 more times I think we're trying to say the same thing 😀

 

[rxmd]

The idea of the system is nice, but the implementation could have been better. The bayonet mount is ridiculously complicated, with its two bayonets and the helical that has to be properly aligned and the external retaining spring. One could imagine a simpler system with a large throat and a "teethed" twist-lock bayonet. Rangefinder transmission could work using a rotating flange on the back of the lens with a pin that snaps into a follower in a rotating ring in the camera. One would mount the lens, turn the focus back and forth once to make sure the follower snaps in, and one would be ready to shoot (like the aperture ring motion for the early Nikon metering prisms).

In addition, the throat is narrow so it's more difficult to build very fast lenses.

Then again it was one of the first bayonet mounts and it competed with a screw mount only, so quick interchangeability might not have been a design goal.

 

[timmyd18]

thank you all very much! i found the discussion about the different ways of solving the same problem very interesting. it seems that Nikon decided to take some of the better features of both the contax and leica designs!

Ondrej I was wondering if the patents had something to do with it. I had read on another thread that Contax was forced to do things differently than Leica. this certainly is different! but if you're going to have the helical on there anyway, i guess it makes sense to let the 50mm lens use it as to make said lens simpler.

I'm new to the Contax/Kiev system so I can't really comment on how its complexity plays out in photographing (although I did find the camera easy to use once I had a manual) but I really think the complexity is part of the charm. I was sure that I was going to break my Jupiter 12 trying to mount it on the darn thing, even banging it a couple of times, but when it finally did click in it sure was satisfying. Sometimes complexity is beautiful.

thank you all for satisfying my curiosity! i can't wait to use the camera more.

 

[Ed S.]

It’s interesting to note that on the Kiev RF, the lens focusing range is dependent on amount of lens rotation. I had never paid much attention to this, until this thread (which caused an attack of Technical Analysis Syndrome).

I looked at my J-8, J-9, J-11 and J-12 lenses for a while to verify this. The amount of "turn" is approximate, but it seems to be consistent for all lenses.
Set lens to Infinity (0), make a quarter-turn, then turn halfway back: 5-meter mark. Turn halfway back towards the quarter-turn mark: 3-meter mark. Reset to 0, make half turn, turn back a little: 1.5-meter mark.

The distance the lens optics move varies considerably. At 1.5meter focus, the J-12 (35mm) has moved out about 1mm; the J-12 (135mm) has moved out 15mm.

I suppose that if this was an SLR scheme, using the 135 to verify focus on an area, then swapping in a wider lens (with the same amount of rotation) might be useful, but since the rangefinder determines focus, this seems to be only an interesting bit of trivia. The result is sort of an "Everyone really does know that, they just might not have realized it" moment.

I suppose that changing the J-3/J-8/Helios-103/Menopta designs to the external mount and deleting the helical from the camera would’ve mostly shifted cost and realized little, if any, savings.


However, this thread might answer a "Lens Adapter" question I asked on a different thread.

An adapter can be built, but since the helical in the camera mount assumes a 50mm lens, SLR lenses (left on infinity) with sufficiently different focal lengths will have problems focusing on the intended subject.

Using an old attachable rangefinder, then focusing the SLR lens using the distance marks, might be worth trying.

 

[rxmd]

I suppose that changing the J-3/J-8/Helios-103/Menopta designs to the external mount and deleting the helical from the camera would’ve mostly shifted cost and realized little, if any, savings.

Well, the Russians did that for the Kiev-5. It only had the outer bayonet, probably to make the whole thing a little less complicated and to allow faster lenses. So there was a variant of the Jupiter-8 (called J-8 NB, with NB standing for наружный байонет, "outer bayonet"), and apparently there also was a similar Helios lens. The experimental Rekord-4 50/f0.9 lens also had outer bayonet only.

An adapter can be built, but since the helical in the camera mount assumes a 50mm lens, SLR lenses (left on infinity) with sufficiently different focal lengths will have problems focusing on the intended subject.
That's an interesting idea, to build a rotating adapter from Contax inner bayonet to various SLR mounts. However I doubt it would work, even for 50mm lenses. One reason is the mechanical strain on the focusing mechanism of the camera if you put something heavy on the internal mount. The other reason is the throat of the bayonet; the film area is larger than the inner bayonet, so if you put an SLR lens 1cm or so in front of the inner bayonet you might already get shading on the left and right edges of the frame.

Philipp

 

[Sonnar Brian]

The Telephoto lenses should be Okay. Both the Contax and Nikon used "Viso-Flex" type lenses. I have a 25cm F4 Nikkor-Q made for Nikon's reflex housing. Nikon and Zeiss made some longer lenses as well, 500mm and longer.

 

[ruben]

It’s interesting to note that on the Kiev RF, the lens focusing range is dependent on amount of lens rotation. I had never paid much attention to this, until this thread (which caused an attack of Technical Analysis Syndrome).

I looked at my J-8, J-9, J-11 and J-12 lenses for a while to verify this. The amount of "turn" is approximate, but it seems to be consistent for all lenses.
Set lens to Infinity (0), make a quarter-turn, then turn halfway back: 5-meter mark. Turn halfway back towards the quarter-turn mark: 3-meter mark. Reset to 0, make half turn, turn back a little: 1.5-meter mark.
.............

Although I have never done such comparizon, I have no reason to doubt it and hence a great practical conclusion in MY presetting of the Kiev focusing.
The idea, if I follow Ed correctly, is that the same presetting of the standard lens is applyiable to the other lenses, thus making their faster use much easier.

Just for clarification, when I talk about presetting the focus I am not talking about DOF or hyperfocal methods, but about finding those points in the distance scale which will give the best possible starting point for yellow patch quick juxtaposition.

I have found that the Contax 270 degrees rotation distance scale has two critical points: If I have my Kiev distance scale set to 3m, I will have a reasonable starting point to quickly find the juxtaposition for objects from infinity to 1,5m. And that by setting the scale to 1,5m I will have a reasonble starting point covering the subjects from 3m to 0,9m.

Now this thread comes and tells me the same goes for all the other lenses, and I find it great news. More than great.

Cheers,
Ruben

 

[Highway 61]

Just for clarification, when I talk about presetting the focus I am not talking about DOF or hyperfocal methods, but about finding those points in the distance scale which will give the best possible starting point for yellow patch quick juxtaposition.

Well, I think you are here basically referring to the famous zone-focus technique, which is a particular hyperfocal sub-technique applied to "candid photography".

And yes it does require what the DOF can bring in (how could the DOF not be counted in ?) as for how it works.

😉

On most of the 24x36 compact rangefinders or guess-focus cameras with a fixed 40mm lens (manufacturers did *not* fit all these cameras with a 40mm lens by chance), the best "starting point" focusing distance, as per how you define it, is usually at 6.0m.

That said, it's pretty logical that you first find your "ideal starting point" to be at 3m with a 50mm lens (or any other lens having the same helical threads pitch because of the particular Contax mount design).

That said just consider the well known "6m zone-focus" trick once and again.

Just have a look at (I don't know if you have a Contax or a similar camera but even if you don't you can get the tip anyway) your Contax DOF scale (engraved around the external bayonet flanges on this very camera, or on each side of the focusing index for any other respectable photo tool).

At f:8 and setting the lens focusing ring at 3m you're in focus from about 5.5m to about 2.3m. Not uninteresting, but could be better... (and pretty useless for "action shooting").

At f:8 and setting the Contax focusing helical at 6.xxm you're in-focus from inf. to 3m. Pretty nicer for quick snapshots, huh ?

Hence the "6m at f:8" very popular zone-focus habit thanks to which you can take nice snapshots even when you don't have time enough to use the rangefinder with a 50mm lens (yeah, works even better with a 40mm lens...).

🙂

 

[ruben]

I am not arguing with the zone focusing method or any other method avoiding critical focus.

I am talking about how to best achieve critical focus in street photography, which to my understanding it means how to achieve critical focus in the fastest way.

Now on behalf of Wlad, a new friend from other thread, let's together tour the Kiev viewfinder, in contrast to other viewfinders and see the pluses and minuses.

The first thing we may notice is the small sex pipe show window to attach our eye to. It seems to me just as a favourable prejudice, that this small eye window was designed this way to "force" our eye to adopt the correct alignment with the internal optical elements. But this is just a prejudice for which I have not the slightest proof.

Once our eye is peering inside we immediately notice the rather dim viewing of the overall picture, a dimness like the style of the Yashica Electros. But in contrast to this dim overall view we notice the highly bright yellow patch. It would be of some interest, some day, to measure this high brightness of the Contax/Kiev yellow patch, because upon my feeling at night photograpy it is relatively close to 1:1. Kindly notice I am expressing a subjective feeling.

Thus, this mixture of overal dim picture and highly bright yellow patch, makes a potentially great dish for fast focusing. But there is a problem in the middle, for us to overcome in an intelligent way.

Both the pre-war Contax and all the Kievs who followed its design, carry the broadest baselenght in distance range finding, (up to day !!!) thus providing us with the most accurate focusing tool ever coupled in any manual camera.

This broad baselength is obviously seen in several features of the camera. One is the broad distance between the two windows. Other is the long travel the lens mount the Contax/Kiev make from minimal focus to infinity focus. And the third and problematic feature is the relatively long travel the yellow patch makes across the viewfinder, following our hand while rotating the lens.

This last feature, for some of us, is a source of confusion and delay when we want to achieve a really fast focusing. It confuses some of us because in a situation in which we must focus quickly and we don't see any double image juxtaposition at the viewfinder - with the added pression of time we go crazy and start to rotate the lens furiously fast, making our situation even worse.

At this point a methodic solution is required to avoid the abovementioned situation, and start focusing, start rotating either the lens, or the small wheel or both altogether, FROM A SITUATION IN WHICH WE DO HAVE SOME KIND OF VISIBLE JUXTAPOSITION, AND RELATIVELY CLOSE ONE IMAGE TO THE OTHER, REQUIRING US ONLY TO REFINE IT A BIT.

It is for this purpose that I forward my two critical points of preset for the Contax/Kiev street photographer in need of fast focusing. 3m and 1,5m

Myself, due to my more usual subjects and my own habits at the street, usualy have my camera setted at the 3m mark and from this starting point I easily fine focus any subject in the range of 1,5m and infinity.

If I am within a bus, for example, and my subjet is sitting at an unknown distance close to me, I preset my camera to 1,5m and I know I will have a nice juxtaposition to start focusing my subject, provided she/he is sitting between 3m and 0,9m. I will raise my camera, fine tune my focusing in a fraction of second, and be able to fire at will.

This is my solution, but by no means the only one. RFF member VinceC, uses a much more refined way. Before raising his camera to his eye, he guesses the distance, set the lens accordingly and then fine focuses the necessary bit.

Cheers,
Ruben

 

[micromontenegro]

I need to ask what a sex pipe show is ;-)

 

[Highway 61]

The first thing we may notice is the small sex pipe show window to attach our eye to.

I have to admit - it's quite an unusual way to describe what a squinty viewfinder is.

Particularly on a photo forum.

Nevertheless, I can't follow all these fresh explanations about the focusing-techniques quite easily. They might be interesting, no doubt, but I just don't get them all.

You know - for me, cameras are tools. I may be too much a pragmatist fellow, and not a poetic-minded guy enough !

🙄