J3 - aperture cleaning

[santino]

hi fellow fsu users,

do you have any special hints on how to clean a J3s aperture blades? It's from 1951 and I quite like it. My plan is to get the glass out without unscrewing the helicoid and to clean the blades with lighter fluid.
Good approach or should I just leave it with the oily blades (at least it won't rust)?

 

[02Pilot]

If the blades aren't causing a problem, you're probably better off leaving them alone. Now, if you were going to do a full CLA rather than just dousing them in Ronsonol, that's a different story, but it's also a lot more time and effort.

 

[rfaspen]

Oh, I'd probably just leave well enough alone. Oil on the blades is not a problem unless its excessive and getting where you don't want it. I've never seen that in a lens that wasn't brutally assaulted by someone who opened it up attempted to "clean and LUBE" it. With WD40 no less!

You could post a photo of the extent of oiling and I would expect someone here can provide better advice. Probably to just let it be.

 

[gb hill]

I have a J-8 with some oil on the blades & never had a problem, even not using a lens hood.

 

[f16sunshine]

It can be a problem in very cold weather or if the oil is excessive it can make it's way to a glass surface in extremely hot conditions.
I agree with the other posts though. If it's not time for other service wait until it is to address the oily blades on RF lenses.

Cheers!

 

[Particular]

If the J3 is anything like a Jupiter 8, it should be very easy to do. Google for instructions, I found several for the J8. I would have gotten by without them also. Just go step by step, and don't force anything. The aluminum used on many FSU lenses is quite soft, so it is easy to damage the threads of the tiny screws.

EDIT:
Here are two;
http://www.pentax-manuals.com/repairs/j3service.pdf
http://www.pentax-manuals.com/repairs/j8service.pdf

 

[kaiwasoyokaze]

actually it's a good question and i heard opinions from both sides either saying it doesn't do any harm or it does.

in the case of the latter, the opinion is that the oil blades cause reflections to bounce off the oil bits on the aperture back onto the glass and causes a loss in contrast.

i was wondering if this is true or just BS from the tire kickers to haggle down prices.

 

[santino]

kim coxon adjusted the lens a few years ago and i relubed the helicoid so it's really smooth - i'll post a picture of the aperture soon.
thanks for your input so far!