Copal 0 Aperture Ring Moves Too Easily

[Policar]

I recently purchased a lightly-used 90mm f6.8 Grandagon-N with a high serial number (green ring). The lens looks as new, but it has a weird problem. Wondering if it really is a problem.

Basically, there's virtually no resistance when I move the aperture blades. I have other, similar lenses in Copal 0 and Copal 1 shutters and there's always some resistance. Is this just because the lens is so close to new? I mean it's almost inertial, like I can tap the dial and it keeps moving a tiny bit. Is this simply due to a lack of wear? It's a very substantial difference.

Also, should I expect soft corners and major fall-off (when shooting chromes) with this lens? I've heard it's not very good, after I bought it, of course, but the 90mm Schneider XL is twice the price... I may split the difference and buy a center filter, though that wouldn't help with softness. Thanks!

[Kevin Crisp]

Some Copal shutters are like that, even brand new. It really doesn't matter in use. I am sure somebody could increase the resistance if you wanted to pay for a CLA you don't need.

[Larry H-L]

I have a Copal 0 that does the same thing, no problem however. I was told that it needs a little more grease to provide resistance.

[Policar]

Thanks! I won't worry about it. I'll just double check the aperture ring before shooting anything.

[SMBooth]

I have a Copal 0 that does the same thing, no problem however. I was told that it needs a little more grease to provide resistance.

Would Vaseline be OK to solve this issue?

[David Rees]

I've got a couple of lenses with this problem; after losing a couple of shots because the aperture changed due to tiny knocks whilst cocking the shutter, I experimented to find a solution.

I found the best thing to do was to insert a piece of thin plastic film as a shim between the rings at the back of the Copal shutter. I cut the shim such that it could not disappear completely inside the shutter. Works fine, and can be removed if you decide it's not right--unlike additional grease.

[SMBooth]

Yes , a better way, just enough to add a little for friction.
Thanks

[Phil Hudson]

Also, should I expect soft corners and major fall-off (when shooting chromes) with this lens? I've heard it's not very good, after I bought it, of course, but the 90mm Schneider XL is twice the price

I do not get soft corners at all with this lens when used at f/16 or f/22 (but they can look soft when viewed on the ground glass at full aperture, especially if you are focusing some way in the distance). It is one of my favourite lenses.

[edp]

In the same situation I've used a small piece of that self-adhesive black flocking paper between the shutter and the lensboard to increase the friction.

[John Koehrer]

Vaseline doesn't attract dust but holds it very well.
You're asking for a CLA much sooner than you would want.