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Jupiter-3 markings in wrong place when lens is mounted?
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PostPosted: Sat Apr 29, 2017 9:44 am    Post subject: Jupiter-3 markings in wrong place when lens is mounted? Reply with quote
I recently picked up a very nice, reasonably-priced Jupiter-3 which, after some gentle cleaning and maintenance, turns out to be a really good example optically, mechanically and cosmetically. I'm very pleased with it.

But there's one odd thing about the lens... when I mount it to an old Zenit-3M, or to my M39/E-mount adapter, the red arrow focus marker is facing downwards, so isn't visible when looking down at the top of the camera.

I can't see any way to move the focus arrow and hyperfocal markings round, as it seems the rear section with the markings and the mount itself is all one solid piece.

I'm wondering if the lens has been modified by someone taking some material off the base to allow infinity focusing on certain cameras. It doesn't look like that's the case, but it's the only reason I can think of.

Any ideas?



PostPosted: Sat Apr 29, 2017 10:35 am    Post subject: Reply with quote
It's not supposed to be mounted on a Zenit (this is not a lens for SLRs), so that's likely your issue. Try mounting it on a Zorki or Fed.


PostPosted: Sat Apr 29, 2017 11:40 am    Post subject: Reply with quote
Mos6502 wrote:
It's not supposed to be mounted on a Zenit (this is not a lens for SLRs), so that's likely your issue. Try mounting it on a Zorki or Fed.


Thanks for the reply Smile

I should have explained a little better...

I'm aware that the Zenit-3M is an SLR and this is a rangefinder lens... however, they both have M39 mounts and I know that the mount on the old Zenit-3M I have lying around is aligned such that both my SLR and rangefinder M39 lenses mount with the markings facing upwards. I do, however, realise that rangefinder lenses can't actually be used on that camera (actually, no lens can - the camera is in dreadful condition and beyond economical repair!).

I'm using M39 rangefinder lenses on my Sony A7II with a Pixco M39 to E-mount adapter. If you look at the photos below, you can see that the rangefinder Industar-50 I've fitted lines up correctly, with the focus markings at the very top. I have a few other rangefinder M39 lenses - Industar 26M and 61 L/D, Jupiter-8 etc. - and they also mount with the markings facing up. But with the Jupiter-3 on that same adapter, the markings are towards the bottom...





PostPosted: Sat Apr 29, 2017 1:37 pm    Post subject: Reply with quote
Reassembled wrong when CLA'd ? Is infinity focus working ok?


PostPosted: Sat Apr 29, 2017 1:40 pm    Post subject: Reply with quote
I don't know the reason, but I maybe see the remedy in your pics, if you are not already aware of it yourself. If your adaptor works similarly to my K&F adaptor, I can see what appears to be openings to grub screws on the body of your adaptor, which on mine, you can back off, centre your thread mount lens and re-tighten.


PostPosted: Sat Apr 29, 2017 2:43 pm    Post subject: Reply with quote
Eddie46 wrote:
Reassembled wrong when CLA'd ? Is infinity focus working ok?


That's the crazy thing... Infinity focus is absolutely spot on, exactly where the hard stop is.

I'm beginning to think it was incorrectly re-assembled (ie. wrong position on the helicoids), and then the owner removed some material from the base in order to have the lens reach infinity focus again.

The more I look at the base and compare it to other Jupiter-3 photos, the more I think this may be what's happened. There are tooling marks on the base around the mounting thread (it should be smooth), and there should be a tiny chamfer on the rear edges of the teeth around the base (as with the front edges) - but that chamfer isn't there.

The lens works perfectly, and the glass is in outstanding condition. Considering how little I paid for it, I'm not too worried - I guess I'll just buy another M39 adapter purely for this lens, and set the inner ring position to suit Smile


PostPosted: Sat Apr 29, 2017 2:45 pm    Post subject: Reply with quote
Sciolist wrote:
I don't know the reason, but I maybe see the remedy in your pics, if you are not already aware of it yourself. If your adaptor works similarly to my K&F adaptor, I can see what appears to be openings to grub screws on the body of your adaptor, which on mine, you can back off, centre your thread mount lens and re-tighten.


Thanks Smile Yes, I was aware - but appreciate you mentioning it.

I use several M39 lenses, but this is the only M39 adapter I currently own. I have it set correctly such that my other M39 lenses are more-or-less properly aligned. It's just this Jupiter-3 that's radically different. As I mentioned in my post above, I think I'll just buy another adapter specifically for this lens and adjust the position accordingly Smile


PostPosted: Sat Apr 29, 2017 11:34 pm    Post subject: Reply with quote
FWIW, my Jupiter-3 has the same 'feature'.


PostPosted: Sun Apr 30, 2017 3:07 am    Post subject: Reply with quote
BigMackCam wrote:
Eddie46 wrote:
Reassembled wrong when CLA'd ? Is infinity focus working ok?


That's the crazy thing... Infinity focus is absolutely spot on, exactly where the hard stop is.

I'm beginning to think it was incorrectly re-assembled (ie. wrong position on the helicoids), and then the owner removed some material from the base in order to have the lens reach infinity focus again.

The more I look at the base and compare it to other Jupiter-3 photos, the more I think this may be what's happened. There are tooling marks on the base around the mounting thread (it should be smooth), and there should be a tiny chamfer on the rear edges of the teeth around the base (as with the front edges) - but that chamfer isn't there.

The lens works perfectly, and the glass is in outstanding condition. Considering how little I paid for it, I'm not too worried - I guess I'll just buy another M39 adapter purely for this lens, and set the inner ring position to suit Smile

The safest option is a dedicated adapter clocked to align the focus distance mark at 12:00, or take it apart to find what was done and reverse it, that your other LTM lenses clock correctly indicate there was some changes to it.


PostPosted: Sun Apr 30, 2017 6:47 am    Post subject: Reply with quote
Thanks for the replies, all.

I'm convinced it has been "worked on"... but as I said, I'm not that concerned, as it was inexpensive and is still a great little lens. I'll be ordering another adapter today Smile


PostPosted: Sun Apr 30, 2017 3:04 pm    Post subject: Reply with quote
With a J-3, the easiest way to correct a lens that cannot drive the RF cam to infinity is to grind down the outer portion of the mount so that the helical can be screwed in deeper.

Helical_in_deeper_to_mount by fiftyonepointsix, on Flickr

If the back of your lens was polished down- it was expertly done, looks very even. I've seen only one that was polished down- was very sloppy.

I've also seen a couple that had thread damage that prevented the lens from being screwed all the way in. Worked on those using a file to fix the threads, and working it into an old parts-only FED-2 used just for such purposes.

A couple of ZK and Jupiter mounts, mostly made just after the war: the markings were off by a large degree. Probably machined incorrectly from the beginning.


PostPosted: Mon May 01, 2017 10:02 am    Post subject: Reply with quote
fiftyonepointsix wrote:
With a J-3, the easiest way to correct a lens that cannot drive the RF cam to infinity is to grind down the outer portion of the mount so that the helical can be screwed in deeper.

If the back of your lens was polished down- it was expertly done, looks very even. I've seen only one that was polished down- was very sloppy.

I've also seen a couple that had thread damage that prevented the lens from being screwed all the way in. Worked on those using a file to fix the threads, and working it into an old parts-only FED-2 used just for such purposes.

A couple of ZK and Jupiter mounts, mostly made just after the war: the markings were off by a large degree. Probably machined incorrectly from the beginning.


Thanks for the info! Smile

Yes, if mine has had material removed (and I'm now 99% sure it has) it was a neat job - not perfect, mind you, as there are visible grinding marks; but very good.

Assuming the serial numbers allow correct dating of the lens, mine's a 1957 model, so not all that early.

I've ordered another adapter so I can have one specifically lined up for this lens. It's worth the small extra spend, as I'll definitely be using it quite a bit.
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