[chedoy]

Hi to you disassembly experts. I have the Kiron/Vivitar 28mm f2. Its aperture blades are stuck. Earlier in this thread, pentaxman showed three versions. I have the middle one. Front element is stationary when focus ring is turned.

I've studied Paulo Gomes Flickr page where he takes the lens apart. I'm attaching his photo where he says that the front element screws off (with a firm twist) after other parts have been removed.

Then I saw Lowell Goudge's note that he just untwisted the lens (presumably the same construction) w/o the other disassembly.

Am I proceeding correctly if I do this? I've had the front cover off, so I could hold the lens by the two surfaces shown in the second attachment. And If I got the halves apart, I would just try to swab down the blades with solvent, rather than disassemble.

...or I could try to get my money back from the seller.

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Last edited by chedoy; 04-28-2011 at 01:34 PM.

[Lowell Goudge]

your photo on the right depicts the points you need to grab.

What I found is that this can be very very tight, (use thread locker) and I use small strap wrenches to undo this.

Remove not just the front elements but the rear as well so all the glass is out of the lens.. Alcohol does not disolve the grease, you need something else like mineral spirits to do that, so keep all the glass away from the solvent.

Then, to dry the blades, use compressed air, this will also force all the oil remaining back off the blades.

note also in the right hand photo, there is a screw visible that is one of 3 that are used to release the focusing collar from the helix, these change infinity focus. In the middle of the photo to the right of the word Lens

there is also a screw, on the mount side that locks the helix tight, the removal of the front element and the stress on the focusing heliz sometiomes make this loose

[SOldBear]

Alcohol does not disolve the grease, you need something else like mineral spirits to do that, so keep all the glass away from the solvent.

Then, to dry the blades, use compressed air, this will also force all the oil remaining back off the blades.

Don't use mineral spirits. It does leave a residue (learned that in woodworking). Naphtha is much better for this purpose.

Be careful with using compressed air. The blades are fairly delicate. I use a Rocket air blaster and leave the aperture assembly open to dry overnight.

Now, the oil problem may come back. I had a particularly stubborn lens with this problem re-occurring every few months. Finally I had to completely dissemble to aperture assembly for a thorough cleaning to make the problem go away for good.

[Lowell Goudge]

Don't use mineral spirits. It does leave a residue (learned that in woodworking). Naphtha is much better for this purpose.

while this is true, by blowing the blades off you force any remaining fluid back off the blades, as well as forcing the oil that is under the plates that hold the fixed pivot of the blades back into the lens body, the issue with residue is if you let the spirits dry by evaporation only. then you get lots I agree.

Be careful with using compressed air. The blades are fairly delicate. I use a Rocket air blaster and leave the aperture assembly open to dry overnight.

the blades can be delicate if you totally disassemble the lens, but if you only take the front and rear groups out, then the blades are well supported because they are interlocked. acan of dust off works just fine (althoug my experience is limited to only 2 Kiron lenses, 24 and 28mm F2's just like the OP's)

Now, the oil problem may come back. I had a particularly stubborn lens with this problem re-occurring every few months. Finally I had to completely dissemble to aperture assembly for a thorough cleaning to make the problem go away for good.

My 24 took a couple of cleanings, also, but I attribute this to the approach taken when I first cleaned them, just addressing the visible part of the blade and letting it dry over night. The more agressive cleaning and blowing them dry by compressed air is more thorough.

[chedoy]

Thanks for the confirmation, Lowell!

What I did in the interim was to set the lens on top of my desktop PC, and the heat softened the oil so the iris worked (as long as the lens was warm). I can see that there is oil on the blades.

Since the front lens assembly appears to go back and forth as a unit, there is no alignment issue in reassembling it, right? If so, my goal is to just to limit the disassembly to that. Pentaxman said its tricky to get the helical threads aligned so I want to avoid that.

So if I can get my fingers on the blades, I'd try to clean them "in situ." A microfiber cloth dampened with solvent hopefully can draw off enough oil with enough applications.

Soldbear, I've read where some owners just dripped naptha thru the aperture arms. But I will try naptha. Alcohol, water, and oil don't mix.

[SOldBear]

So if I can get my fingers on the blades, I'd try to clean them "in situ." A microfiber cloth dampened with solvent hopefully can draw off enough oil with enough applications.

That will work. I actually used a syringe from a re-ink kit (for inkjet printers) to wash the aperture blades with naphtha.

Soldbear, I've read where some owners just dripped naptha thru the aperture arms. But I will try naptha. Alcohol, water, and oil don't mix.

(Head scratching ). Not sure why this is directed to me. Did I mention alcohol or water?

Good luck.

[chedoy]

Just an update. I took the lens apart, gripping it with two channel lock pliers per the pictures. It's right hand thread. Just as described. Twist the top half off and blades are exposed.

Cleaned the blades by closingthem to distribute the oil, wiping with a microfiber cloth with a little gasoline, repeating many times. Blades are snappy now.

This lens has always been way too soft wide open. I was hoping that was due to oil on the element under the diaphram blades. Looked like some there and I cleaned it. Nonetheless, initial tests inside indicate no improvement. Going outside.
.

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[citixman]

Hello~ I got a Kiron 28mm f/2.8 C/Y mount from ebay and found its aperture is a bit oily and the lens around the aperture had some oil spot !
I disassembled this lens until the last step to clean the aperture, because I can't open the final housing of it. Please refer to the photo attached. It is extremely tight for open even I inject some alcohol solvent intp the slits and holes by syringe.

Can anyone help ? Shared album - Anakin Skywalker - Google Photos
Shared album - Anakin Skywalker - Google Photos

[niceshot]

glad i found this