[c5k0]

I'd like to first say "hello".

I'm a long time lurker, first time post.



And of course, this post seems sort of silly...

I recently purchased a Jupiter-37a, and it is mounting upside down with my EOS adaptor. The same adaptor is fine with all of my Takumars and other M42 mount lenses.

This is the only lens I have a problem with.

I've done a search and it seems that there are poorly made adaptors that may mount upside down, but nothing specific on a lens.


Any help would be appreciated.

Thank you,

[xjjohnno]

Mounting upside down sounds kind of whacky. Are you meaning the thread turns in the opposite direction?
If that's the case and they botched the direction the thread should go then for that lens the solution is quite simple but will require a lot of perserverence hunting through Ebay listings. The Russian lenses with an "A" in their series number have a removable and interchangeable mount held on by 3 screws, a lot like the T mounts but not quite the same. Sniff around the Russian Ebay sellers and you should be able to find one. They also make a mount in PK which are rare as hens teeth.

[georgweb]

Welcome to the forum C5k0 (hey is this an upgrade from C3PO .-)

... The Russian lenses with an "A" in their series number have a removable and interchangeable mount held on by 3 screws, a lot like the T mounts but not quite the same.

Exactly. Loosen the 3 screws, turn lens 180°, done. Even better: Leave the inf. mark at 10 or 2 o'clock position, and you will be having more fun in actually using this thing on a DSLR. If you are into sunstars you might want to have the aperture blades aligned to the frame and adjust accordingly.

You might also check the real inf. on your system before. If it is way beyond inf., you could alternatively start building rings from thin sheet metal (masking foil and the likes) til you get the real inf. After that, adjust with the 3 screws to your liking.

BTW this lens is a copy of the CZJ Sonnar design, one of the best lenses you can get in M42 imo.
Cheers, Georg

[c5k0]

Hey,

Thanks for responding.

When I say upside down, I mean it when it's mounted on the camera, the aperture markings are facing downwards instead of upwards. So, it's as if it has to be rotated 180 degrees as it seems George suggest.

George, are you saying all I have to do is loosen these screws and the lens will rotate along the threading of the screw mount?

Can you explain more what you mean about leaving the infinity mark at 10 or 2? Oh, do you mean oriented with the camera - where 12 would be the normal position of infinity?

[georgweb]

Yes and yes.

Have fun with the lens, it's a goodie.

[c5k0]

Thanks for your help.

Turning the ring ended up being a very difficult job. It seems as though somebody had wound pink "spacer" tape around the inside of the mount. So turning the mount was almost impossible, until I removed some of this tape.

I've left the infinity position at 12'. Only because I like the minimum focal distance as short as it can be. I'm assuming if I extend past infinity focus, it will increase the length of minimum focal distance?

On a side note, I just fixed my second lens. A Tamron 90 f/2.5 with aperture blades not closing. Loving mf lenses! And love the rush of taking something apart and almost losing the aperture ring ball-bearing 3x.