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02-21-2012, 03:29 PM   #1
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I dissembled my 35mm, now what?

Hi everyone, I think I may well need the hand of some more experience photographer/DYI/lens repair people.

With the help of this thread (and particularly from wavecurrent), I easily opened the lens and have complete access to the aperture blades.

Here is a picture of where I am at :




My problem is that the aperture blades are slow, but they don't seem to be oily or anything. If I close it down from wide open all the way to f/22, it can take a full second and sometimes will not close all the way.
So I figure the problem is simple enough, but since it doesn't seem to be grease on the apertures blades... I'm clueless. I would gladly listen to your suggestion.

Thank you in advance.

02-21-2012, 03:44 PM   #2
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I took apart a 135mm lens a few weeks ago that had oily blades, but it also had some issues with a little lever mechanism and a spring that seemed to help pull the blades. I've never seen the inside of this lens, but I can see a spring on the aperture lever, and that could lead to a similar spring mechanism. On mine, the "spring" was a single metal arm that was hook shaped, with a bend at the end that caught a second lever. That bend at the end had come off the little lever. I actually had to correct the bend to keep it hooked.

This is really hard to explain, and I don't have diagrams. The simpler version is "It could be part of the mechanism deeper into the lens."
02-21-2012, 03:56 PM   #3
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The problem is often not the blades, but the linkage, as oil from the helical grease can migrate and gum up several places. Looks like you removed the rear lens group. If you also remove the front lens group (so no optics are left), you can try flushing the moving parts of the mechanism with denatured alcohol, then blow or blot the excess and dry it out.
There are times a bit of the right lubricant in the right place is needed, but most often the problem is too much, and in the wrong place.
I'll usually disassemble the linkage parts, and polish them with moly disulfide powder (like graphite), carefully wiping them as clean as possible, then reassemble. That minimizes the friction without any damping action that oil can cause. However, excess powder lube can also move where it isn't supposed to.
Look it over carefully, work the linkage, and figure out how it all works, and where it might be sticky.
02-21-2012, 04:01 PM   #4
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Thank you TomB_tx for the advise... they are not element left indeed. I just find it a little hard to dissemble the rest of the aperture mechanism... I'm not all that good with repair. Not exactly bad, but not an expert either!

I think the problem might me the linkage as you mentioned. Do you think they could simply need some lubricant ?

Here is a picture with two arrows of the place where I think it might slow down (cause it has to turn, so maybe there is a friction somewhere...)



02-21-2012, 04:02 PM   #5
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Thank you pezmaker as well, I see the spring indeed, but it is we hooked as far as I can tell!
02-21-2012, 04:21 PM   #6
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Before any further disection may I suggest you try -----
a few drops of lighter fluid on the blades and on the mechanism.
That should free everything up.
Then keep working the aperture over and over until it runs free without the lighter fluid.
Put it aside for a day and then try it again. You may need to repeat the procedure.
But you wont have to hunt for tiny screws and springs in your carpet.
Despite nay sayers it always works for me.

Mickey
02-21-2012, 04:25 PM   #7
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Thank you Mickey for your suggestion, I think it sounds pretty good! However, I'm not sure what part of the lens is the actual aperture mechanism. Would you suggest I drop lighter fluid on the two region where I pointed some arrows ? Maybe some place else as well ? I value your experience, thank you again!

Karl
02-21-2012, 09:07 PM   #8
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QuoteOriginally posted by mickeyobe Quote
Before any further disection may I suggest you try -----
a few drops of lighter fluid on the blades and on the mechanism.
That should free everything up.
Then keep working the aperture over and over until it runs free without the lighter fluid.
Put it aside for a day and then try it again. You may need to repeat the procedure.
But you wont have to hunt for tiny screws and springs in your carpet.
Despite nay sayers it always works for me.

Mickey
I agree. Naphtha (lighter fluid) is what you want to try. The aperture blades are the black things that open and close when you turn the f/stop ring. Squirt some lighter fluid into a small cup or something and use an eyedropper to put a small drop on the aperture blade assembly and the work the ring to open and close the aperture to spread the fluid around. Wait for a day and repeat if needed. Don't use too much fluid or it will leak onto the glass elements that are still in the lens. This is kind of 'trail and error', but you will gain experience.

02-21-2012, 09:17 PM   #9
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See if this can help.

Pentax M35 2
02-22-2012, 01:16 AM   #10
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Yes.

Mickey
02-22-2012, 05:53 AM   #11
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Oh ! I though aperture mechanism meant something else than the blades themselves! I will put the case of my misunderstanding is from the fact that english is a second language to me haha!
I will try that later today and will let everyone know how it goes!
Thanks again.
02-22-2012, 05:55 AM   #12
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Thank you wlachan for the link, very interesting images... I'll see what google translate can make of the text ! (Although I'm sure in this case that the images speak for themselves!).
02-22-2012, 07:46 AM   #13
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Just a little test that might help. In your second picture with the red lines, the bottom line points to a cam and pin that operate the aperture blades, right? I don't have that same lens but if you move the pin manually with a screw driver, does it operate the aperture blades? If so, when you operate it manually by moving that pin/lever, do the blades snap back fast? If they do not, I would think the problem is in the aperture blades or near by. If it does, then the problem is in the linkage somewhere.
Again, I don't have this lens but have torn apart others, and am looking inside a partially dissembled canon lens that seems to be similar in construction.
02-22-2012, 09:13 AM   #14
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Hey ! Yeah, I did some test like that. When I move the pin, the aperture opens, and when I release it, it does close down to f/22, but slowly, it does not "snap" like you would expect. I just need to go buy some lighter fluid and see if it helps, I guess!
02-22-2012, 10:02 AM   #15
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Not that I'm an expert but my guess would be its not in the external linkage then. I have only completely disassembled the aperture on a couple of junk lenses that I was tearing apart for parts. Each blade had a pin on the bottom that fit into the body of the part. There was an offset pin on the top. There was a thin ring that those top pins fit into (the ring sat on top of the blades). When the top ring would turn, it would push that top pin camming all the blades in and out. While I'm sure lens design vary's, I would think they all would have something similar to make all the blades move together. If the blades look clean, I'm guessing this is the area where there is some contamination or lubricant causing problems. Perhaps if a little lighter fluid on the blades doesn't help, you could put a drop with the lens angled sideways, to try and get it into that side area on the blades. If you did manage to remove the front glass too, perhaps some carefully placed drops of denatured alcohol on the blades with the lens on its side might be able to get in there and free things up? These are not methods I have tried, just some possible suggestions.
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