Nikkor 90mm f4.5, replacement shutter

[watanabe`]

I just received this lens off yahoo auctions in Japan, only paid 27000 yen (285$USD)

Fitted it on the sinar 0 lensboard that came with my norma and I notice there's a slight wobble on the front lens element, not even 1mm, but this seems very bad for my purposes (long exposures at night: 8~30minutest). I really don't want to return the lens; as I doubt I can get another 90mm with such a large aperture (important because I usually do night photograpy) at this price.

I have read that the size of this lens on this small shutter tends to stress the shutter, and am wondering if this may be the cause of this ring coming loose, and a possible fix for it.

It's not the element that wobbles actually, but the shutter speed ring on the front of the shutter (the piece with "copal 0" engraved on it, and the shutter speeds from 500 to B+T). I'm wondering if its possible to do a teardown and tighten up some screws in order to fix this.

Barring that, I am looking at another copal 0 shutter on the same auction site, this one is also a Nikon, but was made for a "AM 120mm f5.6" If I were to buy this; would it be as simple as swapping the aperture measurements on the shutter that came with my lens over to the new one? Or would it need to be readjusted to give proper measurements? I've also read about These lenses using shims custom machined at the factory to adjust for variations in individual lenses. I assume if my lens has one it would be a simple swap into the new 0 shutter?

Thanks,

Alexander

 

[Nick Zentena]

Is it tight on the board? Did you use a wrench to tighten? Sounds loose to me.

A shutter swap shouldn't be too hard. You need to make sure the spacing is right. Not sure if the lens info is still on the Nikon Europe website but they used to have the diagrams with all the measurements.

 

[watanabe`]

The shutter is firmly fixed to the board: I used one of those rodenstock/linos wrenches to mount it. It's not actually the whole shutter that wobbles, just the shutter speed ring, and the lens. The "back" of the shutter is firmly seated and doesn't wiggle at all.

Any ideas?

 

[colrehogan]

I had the opposite problem. The shutter speed ring on one of my Copal 3 shutters was too tight. I took it to a camera repair shop and the guy there opened the shutter and was able to loosen the ring for me. Is there a place that you can go to which might be able to do that? Alternatively, there are several places that people here use to service their shutters which can take care of this issue without you having to buy another shutter.

 

[j_landecker]

If it's only the shutter speed ring that's loose (and the whole front element doesn't wobble when you try to move it back and forth), then you can try this:
Unscrew and remove the front element (watch out for any shims that could fall off). Turn the locking screwhead (red arrow in the picture) 180 deg, cw or ccw, so that the flat part faces inwards. Use your fingernails to tighten the notched silver retaining ring (clockwise) a few notches. The ring should turn easily. Test and repeat if necessary. If the shutter speed ring gets too stiff, back the retaining ring off a notch or two until things move freely.

As for swapping shutters, you should be able to unscrew and exchange the aperture scales if it's the same type of Copal shutter. On Nikon lenses the scales are printed directly on the band of thin aluminum that wraps around the shutter, so you have to remove the whole band. Alternatively you could transfer the markings onto a sticker on the replacement shutter. The Copal shutters are made with pretty close front-to-back tolerance, so you should move any shims that are there across with the front element.

Stress from the weight of the elements would cause loosening of the screws that hold the two halves of the shutter together. These are accessible from the rear of the shutter, but are buried under a couple of layers of rings...

Jim

 

[watanabe`]

Thank you for the detailed replies!

I ended up buying the 120mm copal 0, but emboldened by the fact that I would have a working shutter soon even if I horribly destroyed the one in my possession, I bought a set of mini-screwdrivers and went to work on it. From behind I removed 3 small screws which held a silverish retaining ring in place, which in turn held the aperture ring, which finally held the open/close shutter ring in place. Underneath all three of these were 4 screws, which sure enough, were loose.

Few wristurns later, and 2 attempts trying to get everything back together and still functioning I now have a new problem: what lens to buy for the new copal 0 shutter I'll be receiving in the mail soon