Kiron 28/2 wide open

Teo · Joined: 19 Jul 2014 Posts: 1079 Location: Romania

Got this with stuck aperture at f2 , so ,rather limited use of this softish one :

Oldhand · Posted: Sat Apr 11, 2015 10:21 pm Post subject:

Those images are quite good for wide open.
Is the lens diaphragm faulty?
I only ask because sometimes on Canon FD the aperture blades will not close unless that ring on your adapter is also in the correct position.
It is marked with a double ended arrow and actually opens and closes the aperture from wide to the selected f stop.
If it is in the opposite direction, then nothing happens to the aperture blades when the aperture ring is rotated.
Of course, you might already know this, but it is worth checking
OH

Teo · Joined: 19 Jul 2014 Posts: 1079 Location: Romania

Indeed, is is a diafragm blocked wide open. I had no time ,mood ,guts and motivation to try to open it and fix it , .I'm not good at these things. I just acceped the fact that it is a good portrait lens in somesituations , and I plan to use for this purpose on a m4/3...

Lightshow · Joined: 04 Nov 2011 Posts: 3669 Location: Calgary

28/2 is uncommon enough to warrant a trip to be serviced, and the wide open IQ also look good enough too.

Teo · Joined: 19 Jul 2014 Posts: 1079 Location: Romania

Pancolart · Expire: 2013-11-18

There is some chance lens isn't faulty but you have to mount adapter correctly, all those FD pins and levers combination is a mess sometimes Smile

. Try different combinations of mounting perhaps.

Lightshow · Joined: 04 Nov 2011 Posts: 3669 Location: Calgary

Looking through the adapter, with the lens mounted, is the aperture lever pushed most of the way when you turn the adapters lock ring to engage the aperture?
You can also test it off the adapter, at the 12:00 position, there is a pin that lets the breech lock ring turn, then with the sens aperture set to a smaller f stop like f8, push the aperture lever to see if the aperture moves.
I know from experience that it is real easy to misalign the aperture linkage when reattaching the mount.

doomed-forever · Joined: 09 Aug 2014 Posts: 239

The Kiron 28/2 is a great Wideangle Lens, i do own a decent copy for C/Y Contax-Yashica Mount.

Gardener · Joined: 22 Sep 2013 Posts: 950 Location: USA

Gardener · Joined: 22 Sep 2013 Posts: 950 Location: USA

doomed-forever · Joined: 09 Aug 2014 Posts: 239

thanks god, my Kiron 28/2 is into mint condition and works like it should - no sticky or oily aperture blades. Wink

TedHarris · Joined: 10 Sep 2014 Posts: 23 Location: Manchester UK

I have a Kiron 24/2 which is essentially the same build but with different optics. Mine has aperture blades that stick caused by the grease from the focus mechanism becoming fluid and running into the iris control. I can free them with lighter fuel after removing the front and rear lens groups but this is a fix that I found on the web and was short lived. The lens has joined the box of projects that require more time and patience after the purchase of better screwdrivers to remove the iris from the lens barrel.

dan_ · Expire: 2016-12-19

luisalegria · Expire: 2018-01-18

I have fixed a couple of these.
The solution is indeed naptha/lighter fluid, but the idea is to get rid of the old grease.
So the process is -

- Open lens from the back, remove rear elements to get access to iris/aperture mechanism. Disassembly is very easy with this lens.

- Use naptha/lighter fluid to unstick the blades, use the internal lever (it will be obvious when its open) to open and close the blades.
- while the blades are wet, wipe them with something absorbent, this removes the old grease thats dissolved in the naptha.
- work the blades many times to get them wet again, and wipe them every time.

- When dry, it will begin to stick again, though not quite as much probably. Repeat the naptha treatment/wiping as above.

- Eventually it will start to work when its dry. Leave it open overnight at least to make sure all the naptha is evaporated.

- If it still works the next day, or is almost working, I used graphite lube - pour a very small amount on the blades, wok the mechanism, and then blow it all out a few more times after working the blades.

- Clean the surface of the lens in front of the aperture, it will probably have gotten naptha, grease and graphite on it.

- Let dry another day.

- Verify its all working again

- Reassemble.

Yes, its tedious, but pretty easy.

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

Luis, thanks for your post. This is what I do when servicing a lens of this type. The main thing to remember is to take your time and do a thorough job. You can't expect this process to be a quick one, unless you completely dismantle the lens and submerge the iris mechanism in naphtha and let it soak for a while.

The only thing I'd like to point out, just so there's no confusion, is the graphite lube you refer to is a solid and not a liquid. It's the same as the graphite powder lube you use to unstick padlocks and such.

luisalegria · Expire: 2018-01-18

Yes, its graphite powder.

BTW, another warning, never apply graphite powder on mechanisms that still have oil, grease or solvent in them, only put it on dry mechanisms.

TedHarris · Joined: 10 Sep 2014 Posts: 23 Location: Manchester UK

Thanks Luis, I'll have another try as it seems that I could sort mine without resorting to removing the iris mechanism to clean each blade individually.