J-12 on Bessa/R-D1 reference

[rxmd]

Hi,

inspired by the recent thread on the Jupiter-12 wideangle on the Epson R-D1, I thought it would be nice to have a list which Jupiter-12's work on the Bessas and the R-D1 and which don't. At present there is a lot of this information in various threads, and it's a pain to look it all up. Maybe when we've got a reference in one place, it will be easier to figure out where a given J-12 is likely to work.

So if you have a J-12 that is known to work (or known not to work) on the Bessas or the R-D1, just add it down below 🙂

Here's mine:

Serial#: 7603823 (first four or five digits should be sufficient)
Manufacturer: LZOS (see AK's logo list)
Coating colour: White
Barrel type: Black
Rear element type: No metal housing, steeply curved
Known to work on: Bessa R (focusing <= 10m, then it hits the curtain)
Known not to work on: -

I've attached a photo for reference, taken with my phone, hence poor quality. It would be nice to have another reference photo for a J-12 with the rear element in a metal housing (possibly for a metal barrel J-12, too).

Philipp

 

[Xmas]

Philipp

Did not want to rain on your parade - but one of the 4x J12 I have in contax mount is really close (<1mm) to one of the Kiev shutter frame surrounds at inifinity (- with a Kiev you have to mount at infinity,) the other J12 and Kievs I have, have more clearance, they all seem to work ok.

So the rear of the lens may not be toleranced tightly, some rear blocks have to be shimmed back for focus or definition. I'd be cautious before mounting any lens on any body...

Noel

 

[ampguy]

black N8402xxx w/ exposed rear element works fine on R-D1, Hexar RF, and M4-P's.

 

[Nickfed]

All J-12s are the same. All Bessas are the same. All J-12s foul in the Bessa.
I believe the problem is the exposure meter sensors, but even if that wasn't there it may foul the shutter.

 

[ZorkiKat]

All J-12s are the same. All Bessas are the same. All J-12s foul in the Bessa.
I believe the problem is the exposure meter sensors, but even if that wasn't there it may foul the shutter.

This was my initial belief too. It is apparent now that there are indeed differences. I've seen a J-12 mount and focus nicely on a Bessa.

Then there's the FED and Kiev versions of the J-12. There are also Bessa with Contax/Nikon mounts.😀

There are also differences among the J-12 which determine whether they'd mount easily or not even on FED or Zorki cameras.

Jay

 

[rxmd]

Hi Nick,

All J-12s are the same. All Bessas are the same. All J-12s foul in the Bessa.
I believe the problem is the exposure meter sensors, but even if that wasn't there it may foul the shutter.

it's not that easy. I wouldn't have started this thread if my Jupiter-12 didn't mount on my Bessa-R. Like Jay, I too initially thought that it was impossible and only tried it after a couple of beers on Roman's veranda, and lo, it worked 🙂

Incidentally, the problem with my Bessa-R and the J-12 is not the light meter but the shutter. Alfred Klomp writes that his J-12 (#7201982, LZOS, black, exposed rear element) jams against the light meter on his Bessa-L, while mine screws in entirely with the shutter on "B". So no, all is not the same.

I have taken pictures with this combination. There is a number of posts scattered across various RFF threads that say something similar. It's an oft-colported factoid that no J-12 will work on any Bessa-derived camera, but it's apparently not that easy.

Philipp

 

[roundg]

Pls note that the meter sensor is in different postion in T, R2 from R and L.

 

[Spyderman]

As far as I know all J-12 are the same.

Some people say their J-12 is compatible, because they can mount it. The key is that you must start to mount it with the lens focussed to the closest distance. But how far can it focus? Some can focus to 10m. My J-12 can focus to only 3m, and some don't make it even to 2m.

IMO there is some variance among the Bessas. The rear element of J-12 is stopped by a baffle around the light meter sensor, so that it won't hit the shutter curtains. And exactly there might be the variance, because this baffle could be positioned just a fraction of mm differently and cause the difference "when" the lens hits it. On a 35mm lens it takes just a little move of the glass to focus from 3m to 10m. And that seems to be the range in whch the lens usually hits the baffle.

I doubt the Soviets ever changed the optical formula for the J-12. Maybe just slight recalculations based on the glass.

 

[rxmd]

Hi Ondrej,

IMO there is some variance among the Bessas.

Could be. On mine the rear element doesn't hit the baffle at all. With the shutter on "B", I can screw it in all the way and set it to infinity. With the shutter closed, I can still screw it in and set it to infinity, in which case the shutter will bulge outwards slightly. No baffle gets in the way. I didn't try releasing the shutter, obviously.

The Bessa and the R-D1 are highly similar cameras (some say more or less the same). I haven't been trying to search the archive for anyone who can focus it to infinity on the Bessa R/R2/..., but there are users who can focus their J-12s to infinity on the R-D1 and take pictures (see thread above). So either the shutter curtains have quite a different shape in the two cameras, or there are J-12s that work. On the other hand, it might well be that the shutter is built differently, because it doesn't have to be as light tight on a digital camera; it would be nice if someone who has both cameras or who is familiar with their construction could verify if the shutter is different.

I doubt the Soviets ever changed the optical formula for the J-12. Maybe just slight recalculations based on the glass.

Well, that's exactly what we're trying to find out here. I don't know what result a slight recalculation might have on a lens like this; after all we're talking about variations on the order of magnitude of a millimeter. It could also have to do with the mechanical construction of the rear element. Or both.

Philipp

 

[Adam-T]

I think the question is "Is it worth the risk" - I love FSU Kit too but the CV Skopar 35mm F2.5 doesn`t cost the earth and is absolutely Tack sharp wide open, very contrasty, doesn`t front focus and handles better (well, the Pancake ones do anyway) - I know that J12s can be picked up for £35 compared to £125 for a mint CV 35 but I`d still pay the extra and leave the J12s for use on the FSU cams just in case....... Just my thoughts of course.

 

[ZorkiKat]

LTM and M mount Bessa

LTM and M mount Bessa

I think the issue about J-12 incompatibility with Bessa started with the attempt to mount these lenses on the screw mount versions of the camera. I believe the first (Cosina) Voigtländer Bessa came out with "L" (LTM 39) mounts. Then came the M-mount version.

Did all the reported troubles involve the screw-mount Bessa bodies? Are there
similar observations with the M-mount versions? The M-mount would require a 1mm adapter and increase the seating distance between lens and camera shutter. However, I don't really know if this is a valid assumption since the increased flange distances between an LTM Bessa and an adapted M Bessa is equal at 28,8mm. Or would the LTM-M mount really seat the J-12 a bit farther so that its rear doesn't mess with the shutter blinds or meter sensor?

Many of those who have been able to use the J-12 on their Bessa or RD-1 claim that the extra 1mm of the flange puts the J-12's rear extension just within the 20,5mm allowance given by Cosina or Epson.


Jay

 

[rxmd]

Hi Jay,

I don't think there's a difference between the R and the R[23][AM]. Lens register is lens register. The M-mount bodies, like Leicas, have the mount recessed by 1 mm, otherwise no screw mount lens would work.

The observed different behaviour of different J-12s on different bodies can really only have one or more of the following reasons:

* lens:
-- constructive differences between lenses, e.g. from different plants or different years (this should be a systematic difference)
-- individual differences between differently shimmed lenses
* body:
-- different shutters (this should be a systematic difference)
-- individual differences between mechanical protrusions in the shutter chamber between individual cameras (sounds improbable to me)

Philipp

 

[Nickfed]

I think the issue about J-12 incompatibility with Bessa started with the attempt to mount these lenses on the screw mount versions of the camera. I believe the first (Cosina) Voigtländer Bessa came out with "L" (LTM 39) mounts. Then came the M-mount version.
Jay

How can this be? No matter what you've got, the distance from the rear glass of the J-12 to the film is the same, and changing the lens mount fixes nothing.
I submit that the only way it's gonna work is by variations within the camera, or the lens is faulty.

Somebody like Gandy should know of variations in Bessas. I'm surprised that they would bother to change anything, as they are made on the cheap.

Further, I understand that the exposure sensor is part of the problem and it's on some sort of swinging arm that gets it out of the way when the shutter fires. Consequently, installing the lens with the shutter open on "B" is a fool's errand that proves nothing.

Again, the Gandy website may have something on this, or Klomp

 

[rxmd]

I understand that the exposure sensor is part of the problem and it's on some sort of swinging arm that gets it out of the way when the shutter fires. Consequently, installing the lens with the shutter open on "B" is a fool's errand that proves nothing.

No Bessa has an exposure sensor on a swinging arm; about the only mainstream cameras to have such a setup were the Leica M5 and CL. Instead, the Bessa reads reflected light of the shutter curtain. This would be difficult with a J-12 (the Hexar RF apparently manages), but it would not prevent the lens to be mounted.

Philipp

 

[ZorkiKat]

Hi Jay,

I don't think there's a difference between the R and the R[23][AM]. Lens register is lens register. The M-mount bodies, like Leicas, have the mount recessed by 1 mm, otherwise no screw mount lens would work.

The observed different behaviour of different J-12s on different bodies can really only have one or more of the following reasons:

* lens:
-- constructive differences between lenses, e.g. from different plants or different years (this should be a systematic difference)
-- individual differences between differently shimmed lenses
* body:
-- different shutters (this should be a systematic difference)
-- individual differences between mechanical protrusions in the shutter chamber between individual cameras (sounds improbable to me)

Philipp

Hi Philipp

Could there be significant changes in the RD-1 then which makes the adaptation of J-12 in this camera possible? Though it is still a Cosina Bessa body, there could well be some modifications which make them different from the film Bessa bodies. In one Japanese site, the writer said that the LTM-M adapter made the difference. This comment is echoed in other sites as well.

BTW, the RD-1s has what looks to be the front shutter which covers the real shutter in film Bessa cameras. The original shutter configuration seems to have been retained in the conversion to digital. Attached is a picture of the shutter (its in my yet to arrive RD-1s! 🙂) as seen from the lens mount. If that is indeed the case, then shutter thickness remains the same. Its light colour would suggest that it's being used by the light meter sensor for measuring exposures, like in the film Bessas.

Jay

 

[ZorkiKat]

Measured the back extension of my LTM J-12

Measured the back extension of my LTM J-12

My J12's (Nr 8300057) back extension with an LTM->M adapter, measured with a caliper, is about 20,2 to 20,4 mm. I couldn't really say for sure since repeated measurements gave slightly different values, but none were over 20,5mm. The lens was measured at its infinity setting. This would put it within the range of lenses with protruding back elements allowed on the R-D1.

Do the Bessa film cameras' instruction manuals carry a similar note regarding the sort of lenses which may be used with it?

Jay