Jupiter-3 aargh!

[Mr_Flibble]

For a second time in about 2 months time the aperture ring on my '57 J-3 locked up during a photo-session.

So I unscrewed the front element, again,and let a few drops of lighter fluid work its way into the aperture ring. That frees it up beautifully, but a day later when the naphtha has evaporated the thing ceases up again. :bang:

I'm not afraid to tinker around with optical devices (like a 1915 Barr & Stroud Infantry Rangefinder), but when it comes to taking screwdrivers to lenses I'm rather uncertain of myself....

I'm afraid it's time to send it in for a CLA....

 

[Sonnar Brian]

If the glass is good, it would be easier to swap with a different fixture. I have spares. Several.

The glass is easy to drop out if you have a spanner, and the cone that controls the aperture mechanism is easy t take off- one screw makes the connection. It comes out, unscrew the cone. I would drop out all the glass, take off the aperture cone and see what's going on. Could be a set screw binding, or metal shavings. As to taking out all the blades, I'd just grab a different module.

 

[Mr_Flibble]

Thanks Brian, I spotted your PDF on disassembling/adjusting these lenses. That should be a big help. I'll see about taking it apart later when I get home from work.

Can I send you the bits if it all goes horribly wrong? 😉

I think the problem is the fine dust that got into the lens in September. It probably turned the grease into a cement.
I didn't dare to dissamble the lens far enough to clean out all the gunk.

 

[Sonnar Brian]

I can send you a module or move the glass to a new module and shim it, not hard.

The rear group simply unscrews, I use a rubber mat to do it. If you took out the front glass and triplet behind it to get to the aperture- that was the hard part.

 

[Mr_Flibble]

Right, I've unscrewed the lens module from the outer casing as before.
worked some alcohol into the the mechanism instead of lighter fluid,
same result, the aperture ring moves freely.

I'll see about removing the rear lens element now.

 

[Mr_Flibble]

No luck removing the rear lens element. I could've sworn I had one of those rubber friction mats (for opening jars and the like), but I guess I'll have to go buy one.

I've removed some dried-up grease from the edges of the aperture cone, but I would like to get it off to relube the darn thing.
To get the cone off I take it I'll have to remove the adjustable stand-off ring? Will this screw-up the focus?

 

[Sonnar Brian]

Yes- remove adjustable ring. Scribe a mark to get back on, and there are two taps in the correct position.

I use a rubber mouse pad for the rear group. If that does not work, the spanner will.

 

[Mr_Flibble]

I use a rubber mouse pad for the rear group.

Good idea, of course all the mouse pads disappeared from my house when I started to invest in optical mice :bang:
Dad should probably still have a few spares lying around. Time for a visit 😉

Someone has already put a mark on the adjustable ring. I'll let you know what happens.

 

[monocyte]

My '52 J3 is having similar difficulty: I was able to get the focus mount apart and relubricated last night, but the aperture remains quite stiff, to the point where it's possible to start to unmount the lens when trying to adjust it.

In the recent J9 thread Jay mentioned trying a mixture of naptha and sewing machine oil if naptha alone didn't do the trick. This seemed like it provoked some disagreement, though, with someone suggesting it was possible to foul the elements this way. Would this approach be workable on a J3 with similar caveats?

 

[Mr_Flibble]

That went pretty well,

After removing the cone I found a big hardened glob of grease on the inside of the funnel-shaped part.
I wasted a number of Q-tips and lots of alcohol wiping down the surfaces until none of the grease/concrete remained.
Cleaned more of the stuff out off the threads and little channels on the lens module until it was clean.

Then I put some fresh (weapons grade) grease on the funnel-shaped parts of the cone and the lens module and reassembled the bits. I just lined up the marks on the cone and stand-off ring that were already there.

By looking at some quick R-D1 test shots all appears to be in order.

Thanks for the input Brian.

 

[johannielscom]

Right! Well done, Rick!

I have this thread marked, in case I ever need to perform that trick myself, thanks Rick and Brian!

 

[raid]

That was a good example on how RFF can help you out. Brain did a great job in guiding Rick.

 

[Mr_Flibble]

Here's one of the test shots. f/4, 800ISO at 1/15th.

At f/1.5 I've noticed that focus is slightly off at the shortest distance. But that might already have been the case before I started. It could be I need to give the aperture cone a half-turn before replacing the screw that connects it to the aperture blades. Though that would not affect the focus, right? Only the stand-off ring and the shims would. But for normal use in its current state I don't think it will be a problem.

 

[Sonnar Brian]

Make sure all of the glass is well-seated and in all the way. The glass being out of place can also throw focus off. If the glass is well seated, triplet pushed thoroughly in place, front element well-seated, and rear module firmly screwed in- the only other thing that controls focus is the main shims and stand-off ring. You would have nboticed the red dot for the aperture ring not aligning with the index line for the focus if the variable ring was off.

>This seemed like it provoked some disagreement, though, with someone suggesting it
>was possible to foul the elements this way. Would this approach be workable on a J3
>with similar caveats?

I use Naptha only on the aperture blades. It has plenty of oil around! Usuallu get as much off as possible.

 

[Mr_Flibble]

The red dot lines up perfectly with both the extremes of the aperture ring movement.
I never got so far as to removed the glass from the lens module.
The rangefinder on the R-D1 might be another reason the focus was off. I confess I did not check the actual range to the subject.
At this point, I'm not too worried about it though. 😉