TenEleven
Well-known
This is sort of a trip report/blog/rumination on my attempt to modify a cheaply bought Jupiter 3 to the LTM standard.
I got a Jupiter 3, for a measly ~$85 locally. For such a low price you are going to assume that the lens had its share of problems -- and you would be right. Upon first inspection the helicoid was so frozen that any attempt to focus unscrewed the lens. The aperture adjustments too slick, the blades covered in oil and the lens hazy throughout.
So I disassembled and CLA'd the lens. Since this is standard procedure I'm not going to detail it here. However, the lens cleaned up nicely. With the exception of the main-shim, which was laughably off - infinity could not be reached until f/5.6.
Since the mechanics and glass were both very nice and the lens was very sharp on my NEX-5, I decided it was a good candidate for the modifications Brian so generously detailed here.
Using my crude tools (don't have a workshop & locked-down) I slowly filed and sanded the rear mount of the lens down until it agreed with a known good Leica M2 at all focus distances. I used a ground glass taped to the film rail, viewing with the lens wide open through a 42x magnifier to verify focus at infinity, 3m and 1m. This required some back and forth but eventually I got there.
According to my calipers I sanded off about 0.8mm.
Next I adjusted the main shim for good infinity focus at f/1.5. And re-tapped the aperture index so it would line up. This was my first mistake, but read on.
After all this I tested the lens on film using the same Leica M2 camera with a Leitz M/L adapter. (Personally after a lot of bad experiences I'd recommend against off-brand M/L adapters.) The results showed a lens that had amazing performance at f/1.5 and followed the rangefinder spot faithfully until the closest focus distance was reached.
This all seems "too good to be true" because that's some amazing performance from this old Russian lens. And sadly it was. Stopped down it was another story entirely:
I tried to re-calibrate the main shim, leaving the inter-lens distance the same since focus seemed to follow the RF fine already. I also redid the aperture index, which after several re-doings wouldn't hold its grub screws anymore. For now I've taped it in place since this is likely not the last adjustment it will go through.
None the less, the result was ... well .. let's say .. humorous amounts of focus shift:
Now, I can hear you say: "But Manuel, that's just how Sonnars work. Focus shift is a fact of life!"
Well, maybe on a digital camera. But on fine-grain film, so far I've never had any issues whatsoever.
To prove this point here's my 2859xxx LTM 'T' wartime Sonnar that is somehow uncoated(!?). (Note to Brian: This lens will eventually get a thread of it's own together with other "weird" Zeiss Sonnars I have.) It is very close and representative to my other LTM/Contax Sonnars in its behavior.
Note that the thin veil disappears as you stop down a bit beyond f/1.5, but the focal point stays exactly at the RF indicated position. Nice!
I have omitted the closest focal distance to avoid overloading the thread. Truth be told I've also shaken the camera at the f/2.8 setting. Anyway, the story is much the same as the other two focal distances:
Does have anyone any thoughts on this? Is the Jupiter 3 focus-shift a given? Should I just save the various lens elements to "rescue" other lenses?
Is my Jupiter 3 just a bad apple? Are Jupiters more prone to focus-shift?
PS: I tested the Jupiter-3+ from Lomography and perhaps unsurprisingly it has similar, perhaps less extreme, behavior to its older brother. I still like that lens though. It still exhibits strong focus shift VS the original Sonnar types, however.
I got a Jupiter 3, for a measly ~$85 locally. For such a low price you are going to assume that the lens had its share of problems -- and you would be right. Upon first inspection the helicoid was so frozen that any attempt to focus unscrewed the lens. The aperture adjustments too slick, the blades covered in oil and the lens hazy throughout.
So I disassembled and CLA'd the lens. Since this is standard procedure I'm not going to detail it here. However, the lens cleaned up nicely. With the exception of the main-shim, which was laughably off - infinity could not be reached until f/5.6.
Since the mechanics and glass were both very nice and the lens was very sharp on my NEX-5, I decided it was a good candidate for the modifications Brian so generously detailed here.
Using my crude tools (don't have a workshop & locked-down) I slowly filed and sanded the rear mount of the lens down until it agreed with a known good Leica M2 at all focus distances. I used a ground glass taped to the film rail, viewing with the lens wide open through a 42x magnifier to verify focus at infinity, 3m and 1m. This required some back and forth but eventually I got there.
According to my calipers I sanded off about 0.8mm.
Next I adjusted the main shim for good infinity focus at f/1.5. And re-tapped the aperture index so it would line up. This was my first mistake, but read on.
After all this I tested the lens on film using the same Leica M2 camera with a Leitz M/L adapter. (Personally after a lot of bad experiences I'd recommend against off-brand M/L adapters.) The results showed a lens that had amazing performance at f/1.5 and followed the rangefinder spot faithfully until the closest focus distance was reached.
This all seems "too good to be true" because that's some amazing performance from this old Russian lens. And sadly it was. Stopped down it was another story entirely:
I tried to re-calibrate the main shim, leaving the inter-lens distance the same since focus seemed to follow the RF fine already. I also redid the aperture index, which after several re-doings wouldn't hold its grub screws anymore. For now I've taped it in place since this is likely not the last adjustment it will go through.
None the less, the result was ... well .. let's say .. humorous amounts of focus shift:
Now, I can hear you say: "But Manuel, that's just how Sonnars work. Focus shift is a fact of life!"
Well, maybe on a digital camera. But on fine-grain film, so far I've never had any issues whatsoever.
To prove this point here's my 2859xxx LTM 'T' wartime Sonnar that is somehow uncoated(!?). (Note to Brian: This lens will eventually get a thread of it's own together with other "weird" Zeiss Sonnars I have.) It is very close and representative to my other LTM/Contax Sonnars in its behavior.
Note that the thin veil disappears as you stop down a bit beyond f/1.5, but the focal point stays exactly at the RF indicated position. Nice!
I have omitted the closest focal distance to avoid overloading the thread. Truth be told I've also shaken the camera at the f/2.8 setting. Anyway, the story is much the same as the other two focal distances:
Does have anyone any thoughts on this? Is the Jupiter 3 focus-shift a given? Should I just save the various lens elements to "rescue" other lenses?
Is my Jupiter 3 just a bad apple? Are Jupiters more prone to focus-shift?
PS: I tested the Jupiter-3+ from Lomography and perhaps unsurprisingly it has similar, perhaps less extreme, behavior to its older brother. I still like that lens though. It still exhibits strong focus shift VS the original Sonnar types, however.
