For My M8: Jupiter 3? I love the look of this lens, especially for the price!

[eleskin]

I am getting a new disease (meaning I am developing an itch for yet another lens) and this time it seems to be the good old Jupiter 3.

For My M8 I have a slew of 50mm lenses (50mm Summicron, 50mm Noctilux f1.0, 50mm Summitar (what a sleeper an pleasant surprise the Summitar is!) , Industar 61LD, Jupiter 8.

I love the look of each lens for a specific look. The Jupiter 3 has my eye for its Summitar like contrast, buttery bokeh, and decent sharpness as well as pleasant color.

The problem I have is these Soviet lenses are Contax standard, so I compensate by shifting focus slightly to get decent results, but oh would I love them to match my M8 rangefinder!

I know Brian Sweeny has modified Jupiter 3 lenses with great sucess and I am very impressed with the results.

I have done some reading on how to adjust a J3 and I see two methods. Shim the lens or move the rear element. So knowing this, which is the easy way to adjust the lens (if there is?).

 

[Sonnar Brian]

Moving the rear element in reduces the focal length: the problem is you need to grind the optics module down to screw in closer to the aperture. There is not enough room to completely correct the focus error. You need to shim it anyway. I only move the rear optics if the focal length of the J-3 is "far-side of normal".

Easiest to adjust the main shim. I optimize for close-up and wide-open. For infinity: stopping down causes the shift in focus to go towards infinity.

ON the M8:

Close at F1.5:

Far at F4

 

[eleskin]

Thank's Brian

Thank's Brian

Thank's for the help Brian.

So you are telling me the easiest way is to adjust the shim slightly. I have taken apart both my Industar 61LD and 35 mm Summicron V. 4 for lubrication, and the Jupiter 3 does not look that bad with unscrewing the front element lens cell. I am interested in closer range portraits more than infinity so from your description, that is how I would set up my lens too.

So what will I need to adjust the lens? I would guess another shim. Would I be able to find a shim at a hardware store?

Thanks.

Ed

 

[Uwe_Nds]

You may also stick some parcel tape on one of the existing shims and then cut off the excess - IMHO much better than tin foil which starts to crumble when screwing in the optical module.
If necessary, use several layers of parcel tape to build up the required thickness.

Cheers,
Uwe

 

[Sonnar Brian]

Kim Coxon is hosting my original instructions for the J-3 work:

http://pentax-manuals.com/repairs.htm

And a teardown for relube here:

http://www.ziforums.com/showthread.php?t=374