how do you adjust a Jupiter 12?

[gabrioladude]

My cameras for this lens are a Kiev 4a and a Contax II. I wanted to shoot with a 35mm lens without breaking the bank and so purchased a Jupiter 12 off of ebay. This was after having read many of the comments that talked about what a great lens this was. And yes I also read that it was a matter of chance.

Well my lens is abit of a lemon...

It really is not very sharp, only at f16.

Does anyone know how to adjust the elements of the lens to get it to be more sharp?

thx

 

[Sonnar Brian]

Is the focus off, ie in front or back of what the RF indicates?

I would check the glass, that it is in tight. It sounds like it is misassmebled, with something left out. You might post some pictures of the lens, and taken with the camera.

When the lens is mounted, make sure the Kiev focus wheel is turning as you focus the lens. That indicates it has engaged the pickup.

 

[gabrioladude]

Brian, thanks for the response

after getting your email, I checked the focus wheel (was mounted on the Contax II) and it didn't seem to turn well (ie with difficulty). Then mounted it on the Kiev 4a and it turned fine. Put it back on the Contax II and it then again turned fine. So it sounds like I didn't have it properly mounted. Probably a false alarm. Will do some more testing before I try anything else.

As a point of interest. This testing exercise was actually about seeing whether I have a shutter problem with my Contax 2a (which I discovered I don't)

Started with the prewar uncoated Sonnar 50mm f1.5 on the CII and the Coated Sonnar 50mm f1.5 on the C2a. The post war is definitely the superior lens.

Then I mounted two 135 lenses on the two Contaxes. The coated Jupiter 11 on the C2a and the uncoated Sonnar on the CII. The Jupiter 11 is far superior.

While I had the J12 on my CII, I was testing the 85mm f2 J9 on my C2a, what a beautiful lens that is.

fun playing with these, but more work to do...

The reason I thought I had a shutter problem on the C2a is because I am finding it a challenge to meter accurately when shooting (using a Gossen Digisix). Once you have been used to auto matrix metering on a DSLR and shoot RAW you get spoiled....

 

[Brother Joe]

See my thread in FSU forum about a J12 I had some issues with. Initial problem was looseness of the rear element, followed by my own bumbling. J12 is fine now (tho, it has a bit of "stick" if the aperture is wide open and I am focusing at around 1,2M when on the body. Off the body it's fine.

J

 

[gabrioladude]

thanks for the info Brother Joe, looks very relevant
will pursue this further once I complete another film test
appreciated....

 

[Brother Joe]

If need be, I can take some shots of my lens disassembled if my description is inadequate; which it is, but, once you take the 2 elements out, you're left with 4 pieces:

rear element
spacer
housing
front element

The only thing that stumped me once I had things back in in the right order is:

Whether the front/spacer/rear threads forward in the body, or back in the body; once the two are mated with the spacer inbetween, you'll find it can go either way.

What I discovered is that the aperture is hard to adjust (not enough to grab on the ring) because the whole unit is to be threaded back, closer to the film, and not forward. In my case the aperture ring is nearly flush with the body of the lens and having a filter on is what makes it easy to adjust... I really must find a blank filter ring or something to put there instead of always having an actual filter on as I haven't found a hood for my J12 yet.

Joe