Odd variation in a Jupiter-12

[kb244]

Now I know FSU cameras and lens are among the most varied of devices in their design. I used to have a Canon P and another Jupiter-12, and while it fit one of the most interesting aspects was how close the back element came to the shutter on my P as you can see here.

Its been some time since I sold both the P and the J-12, then I aquired another one, as well as getting another black J-12, since it seems the black ones fit, just like this one does too. But I noticed when putting it into the new one, the rear element seems to be noticiably shorter than my previous version. (I put some film in before I even thought to ask on here).

Maybe I'm just crazy and remembering it wrong, but is it possible for the lens design to be shorter and still yeild the same results, or if it was even common for variations to occur in those lens optical constructions.

 

[kb244]

Or maybe my perspective over time just makes me thing its shorter than the last one...

Oh well was just random curiousity.

 

[Nickfed]

Or maybe my perspective over time.

I suspect that is the case.............

 

[alternatve]

This gives me hope to fit a J-12 on my Bessa R2a. Has anyone tried this combo with good results?

Samuel

 

[kb244]

This gives me hope to fit a J-12 on my Bessa R2a. Has anyone tried this combo with good results?

Samuel

Actually you'll be disappointed , I had a Bessa T which has a very similar shutter setup.

The problem is while the 'box' so to speak is bout the same as the Canon P, the Bessa R2 and T (and the others similar) have a front curtain that is also the reflective surface for the metering. The J-12 goes in too far and collides with the grey shutter curtain. So in a manner of speaking the Bessa's shutter is "thicker" thus closer to the back of the lens, than the Canon P.

Also because of the size of the J-12 circumfrence and how close it is to the back, even if you managed to get it in there without hitting the shutter (ie: you'd have to focus a bit less than infinity so would be restricted on focusing range), you wouldn't be able to meter because the rear element would block the meter's view.

 

[kb244]

Far as other compatibilities I noticed...

A Black J-12 will fit fine on my Fed-2A (Type-2C), but not on the Fed-2C (which I no longer have), because of the cam shape. The tear-drop shape of the 2A vs the more square shape of the 2C. On the 2C you could try to get the J-12 in, but the cam would be scratching/rubbing tightly against the black barrel of the glass itself.

 

[QUAsit]

late black J12 of LZOS production have shorter rear element...

 

[wolves3012]

Far as other compatibilities I noticed...

A Black J-12 will fit fine on my Fed-2A (Type-2C), but not on the Fed-2C (which I no longer have), because of the cam shape. The tear-drop shape of the 2A vs the more square shape of the 2C. On the 2C you could try to get the J-12 in, but the cam would be scratching/rubbing tightly against the black barrel of the glass itself.

The J-12 is a known issue on some FED 2 models. It's in order to bend the sensor arm upwards a fraction, very carefully, to clear the J-12 elements.

 

[mr_phillip]

As QUAsit said, they modified the optical design a little late in the J12s production and some late versions have smaller rear elements. They still won't fit on Bessas though.

 

[kb244]

The J-12 is a known issue on some FED 2 models. It's in order to bend the sensor arm upwards a fraction, very carefully, to clear the J-12 elements.

Which I did on the 2C, thus how I was even able to get the lens in. I'm talking bout the cam scraping against the 'black' barrel of the rear, not the actual rear element.

 

[Spyderman]

You still need to bend the arm a bit more upwards. They you'll be able to mount J-12 without problems.

I've owned J-12 from 1950-ies until 1980-ies, in Kiev mount and in LTM mady by Arsenal, KMZ and LZOS.

I've seen only 2 versions of this lens: 1) early Kiev mount with metal ring around rear element (much like original Zeiss Biogon) and 2) without the metal ring. AFAIK all without metal ring have same diameter of the rear element. Individial variations (probably based on individual collimation of lenses) are possible, but differ only on distance of rear element from the film (and thus also from the shutter).

I seriously doubt the Soviets would recalculate a good lens they took form Zeiss.