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How to fix stuck aperture - KIRON 28/2
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PostPosted: Tue Oct 04, 2011 5:27 pm    Post subject: How to fix stuck aperture - KIRON 28/2 Reply with quote
I pourchased a kiron 28/2 in FD mount and had the ugly surprise that the aperture ring doesn't work(40E). the seller didn't mention that , but I decided not to return it because I thought that I could use it wide open... But after a while , I think maybe I could fix it , even if I don't have experience in dismanteling and recomposing lenses.Is it difficult to do it?


PostPosted: Tue Oct 04, 2011 6:15 pm    Post subject: Re: How to fix stuck aperture - KIRON 28/2 Reply with quote
yinyangbt wrote:
I pourchased a kiron 28/2 in FD mount and had the ugly surprise that the aperture ring doesn't work(40E). the seller didn't mention that , but I decided not to return it because I thought that I could use it wide open... But after a while , I think maybe I could fix it , even if I don't have experience in dismanteling and recomposing lenses.Is it difficult to do it?


Well if it's the blades stuck:- Have you tried setting it at f16 and holding the stop down lever on the back of the lens, and at the same time while holding it in one hand..... give the lens a sharp slap with the other (hand).


PostPosted: Tue Oct 04, 2011 6:34 pm    Post subject: Re: How to fix stuck aperture - KIRON 28/2 Reply with quote
Excalibur wrote:
yinyangbt wrote:
I pourchased a kiron 28/2 in FD mount and had the ugly surprise that the aperture ring doesn't work(40E). the seller didn't mention that , but I decided not to return it because I thought that I could use it wide open... But after a while , I think maybe I could fix it , even if I don't have experience in dismanteling and recomposing lenses.Is it difficult to do it?


Well if it's the blades stuck:- Have you tried setting it at f16 and holding the stop down lever on the back of the lens, and at the same time while holding it in one hand..... give the lens a sharp slap with the other (hand).

Thanks , i tried , doesn't works... should I use a hammer for slapping? Laughing


PostPosted: Tue Oct 04, 2011 6:57 pm    Post subject: Re: How to fix stuck aperture - KIRON 28/2 Reply with quote
yinyangbt wrote:
Excalibur wrote:
yinyangbt wrote:
I pourchased a kiron 28/2 in FD mount and had the ugly surprise that the aperture ring doesn't work(40E). the seller didn't mention that , but I decided not to return it because I thought that I could use it wide open... But after a while , I think maybe I could fix it , even if I don't have experience in dismanteling and recomposing lenses.Is it difficult to do it?


Well if it's the blades stuck:- Have you tried setting it at f16 and holding the stop down lever on the back of the lens, and at the same time while holding it in one hand..... give the lens a sharp slap with the other (hand).

Thanks , i tried , doesn't works... should I use a hammer for slapping? Laughing


Keeping trying erm with your hand say for 5 mins, also the heat of your hand might move the blades. I have the same problem with my Kiron zoom and use an elastic band attached to the lever (at the back) to keep the blades closed at f22 when not in use.


PostPosted: Tue Oct 04, 2011 7:49 pm    Post subject: Re: How to fix stuck aperture - KIRON 28/2 Reply with quote
Excalibur wrote:
yinyangbt wrote:
Excalibur wrote:
yinyangbt wrote:
I pourchased a kiron 28/2 in FD mount and had the ugly surprise that the aperture ring doesn't work(40E). the seller didn't mention that , but I decided not to return it because I thought that I could use it wide open... But after a while , I think maybe I could fix it , even if I don't have experience in dismanteling and recomposing lenses.Is it difficult to do it?


Well if it's the blades stuck:- Have you tried setting it at f16 and holding the stop down lever on the back of the lens, and at the same time while holding it in one hand..... give the lens a sharp slap with the other (hand).

Thanks , i tried , doesn't works... should I use a hammer for slapping? Laughing


Keeping trying erm with your hand say for 5 mins, also the heat of your hand might move the blades. I have the same problem with my Kiron zoom and use an elastic band attached to the lever (at the back) to keep the blades closed at f22 when not in use.

Nope , doesn't work !


PostPosted: Tue Oct 04, 2011 8:13 pm    Post subject: Reply with quote
Oh well...and you did hold the stop down lever at the same time....i.e. looking at the back it would the one on left at about 11 o'clock while the other lever on the right would be at a position of about at 2 o'clock.


PostPosted: Tue Oct 04, 2011 8:52 pm    Post subject: Reply with quote
Excalibur wrote:
Oh well...and you did hold the stop down lever at the same time....i.e. looking at the back it would the one on left at about 11 o'clock while the other lever on the right would be at a position of about at 2 o'clock.

Yes ,I kept down the the one at left (11 oclock)


PostPosted: Tue Oct 04, 2011 8:53 pm    Post subject: Reply with quote
I have one of these lenses in OM mount which also had stuck aperture blades. The problems is oil on the blades and seems not uncommon with Kiron lenses.

The only true solution is to take the lens apart and clean the blades. But, I found I could get the blades to move by taking the rear flange off the lens so that i could access the lever that couples directly to the aperture swivel plate. Normally, this lever is only indirectly coupled to the aperture ring and relies on spring tension to move it. Once the blades get oily, the tiny force the spring exerts is insufficient to overcome the stiction of the oil. Once you have access to the directly coupled lever you can move it gently to unstick the blades and then move it back and forth to free them up. This will be ok for stop-down operation but no good for auto operation as the blades will likely move too slowly.

Mark


PostPosted: Tue Oct 04, 2011 9:00 pm    Post subject: Reply with quote
SXR_Mark wrote:
I have one of these lenses in OM mount which also had stuck aperture blades. The problems is oil on the blades and seems not uncommon with Kiron lenses.

The only true solution is to take the lens apart and clean the blades. But, I found I could get the blades to move by taking the rear flange off the lens so that i could access the lever that couples directly to the aperture swivel plate. Normally, this lever is only indirectly coupled to the aperture ring and relies on spring tension to move it. Once the blades get oily, the tiny force the spring exerts is insufficient to overcome the stiction of the oil. Once you have access to the directly coupled lever you can move it gently to unstick the blades and then move it back and forth to free them up. This will be ok for stop-down operation but no good for auto operation as the blades will likely move too slowly.

Mark

So I have to open it by the back .The problem seems to me that my lens is a Canon FD with ring (that turns for fixing the lens I belive it's somewhat more difficult to open (and put it back) from the rear ???


PostPosted: Tue Oct 04, 2011 9:23 pm    Post subject: Reply with quote
Well, I only have one FD lens (a Canon 50mm f1.8 ), but i don't remember that it was difficult to dismantle. IIRC all the complicated linkages came off with the mount so it was not hard to put together again. Take pictures as you go along and use good quality screwdrivers of the correct size so as not to damage the very small screws.

I think access through the rear is your best option. IIRC the optics in front of the aperture can be removed as one unit and so you can partially clean the blades through the front with a cotton bud and suitable solvent. BUT, the blades need to be moving for this to work. If they are fully open, they are not visible to wipe clean. Without removing the aperture from the lens, the best way to get it moving is the way I've already described.

Mark


PostPosted: Tue Oct 04, 2011 9:42 pm    Post subject: Reply with quote
This lens is one of the difficult lenses, friend of mine did clean mine 24mm f2 Kiron he said he couldn't dissmantle fully, but partially open was enough to clean oily blades.


PostPosted: Wed Oct 05, 2011 7:50 am    Post subject: Reply with quote
yinyangbt wrote:
SXR_Mark wrote:
I have one of these lenses in OM mount which also had stuck aperture blades. The problems is oil on the blades and seems not uncommon with Kiron lenses.

The only true solution is to take the lens apart and clean the blades. But, I found I could get the blades to move by taking the rear flange off the lens so that i could access the lever that couples directly to the aperture swivel plate. Normally, this lever is only indirectly coupled to the aperture ring and relies on spring tension to move it. Once the blades get oily, the tiny force the spring exerts is insufficient to overcome the stiction of the oil. Once you have access to the directly coupled lever you can move it gently to unstick the blades and then move it back and forth to free them up. This will be ok for stop-down operation but no good for auto operation as the blades will likely move too slowly.

Mark

So I have to open it by the back .The problem seems to me that my lens is a Canon FD with ring (that turns for fixing the lens I belive it's somewhat more difficult to open (and put it back) from the rear ???


If the Kiron FD breech lock is similar to a Canon FD breech lock lens, then this might help:-
http://rick_oleson.tripod.com/index-161.html

My Kiron FD breech lock zoom is very easy to dismantle to get at the blades, to free them and add a few drops of lighter fuel.
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