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Archive 2012 · fixing a stuck aperture

  
 
crazeazn
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p.1 #1 · p.1 #1 · fixing a stuck aperture


How do you do this? I've managed to take apart the lens easily enough to separate the helicoid but have no clue how to clean to get the aperture blades to stop down? (rokkor 58)


Apr 14, 2012 at 01:56 PM
jcolwell
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p.1 #2 · p.1 #2 · fixing a stuck aperture


Good luck with this. I usually ask for help after-the-fact, too.


Apr 14, 2012 at 02:44 PM
crazeazn
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p.1 #3 · p.1 #3 · fixing a stuck aperture


well I did a search but couldn't find much on google or here so I figured there are enough of us who many encounter this problem in the future


Apr 14, 2012 at 02:46 PM
Tariq Gibran
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p.1 #4 · p.1 #4 · fixing a stuck aperture


If you can remove the entire aperture mechanism, flood it with lighter fluid and continually move the aperture manually where the spring normally would pull on it.


Apr 14, 2012 at 02:50 PM
briantho
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p.1 #5 · p.1 #5 · fixing a stuck aperture


I've had 2 lenses stuck wide open when I got them, bought at a discount because of the "fault". A little shaking and some banging against something semi soft got them working flawlessly again.


Apr 14, 2012 at 03:19 PM
ZoneV
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p.1 #6 · p.1 #6 · fixing a stuck aperture


crazeazn wrote:
... to separate the helicoid but ...


I didnīt opend my Rokkor 58/1.2 that far, need only to convert the mount.

But from other lenses I cleaned the iris I learned that one not every time need to separate the helicoid.
Too open that is easy, too put it together is sometimes hard, and do put it together the way infinity and iris coupling work is even harder.

Sometimes (!) it is sufficient to several times clean/open/close the iris with isopropanol alcohol or something similar, without disassembling the whole aperture mechanism.



Apr 14, 2012 at 04:39 PM
Tariq Gibran
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p.1 #7 · p.1 #7 · fixing a stuck aperture


ZoneV wrote:
Too open that is easy, too put it together is sometimes hard, and do put it together the way infinity and iris coupling work is even harder.


When I completely disassembled and reassembled the 58 1.2, it was indeed extremely tedious and time consuming to put it back together, mostly due to this very issue.



Apr 14, 2012 at 05:13 PM
sebboh
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p.1 #8 · p.1 #8 · fixing a stuck aperture


Tariq Gibran wrote:
When I completely disassembled and reassembled the 58 1.2, it was indeed extremely tedious and time consuming to put it back together, mostly due to this very issue.


i just had one of mine apart yesterday (cleaning it up for a trade), and i don't believe you actually need to take helicoid apart to remove the aperture. i should check though, i was just doing a cosmetic clean of the exterior parts (i think a previous owner had been a smoker). windex does wonders. the 58/1.2 really is a joy to disassemble compared to some lens designs. i've seen some tutorials online that take needlessly complicated extra steps though.

http://farm8.staticflickr.com/7208/6931848326_a2d512a454_o.jpg



Apr 14, 2012 at 05:32 PM
sebboh
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p.1 #9 · p.1 #9 · fixing a stuck aperture


update: the aperture mechanism can be removed without screwing with the helicoid. will post pictures on how in a few minutes.


Apr 14, 2012 at 05:52 PM
sebboh
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p.1 #10 · p.1 #10 · fixing a stuck aperture


for future reference here's how to get the aperture mechanism out without undoing the helicoid, which is always a pain to put back together:

1) remove name plate from the lens (it unscrews)

2) remove lens barrels – there are three screws on it, once they're removed the lens barrel slides off.

3) remove the front optical cell (it unscrews)

4) remove these screws:
http://farm8.staticflickr.com/7082/7078009289_8af5e63768_o.jpg
5) pull out the black structure those screws were in (the aperture mechanism and rear optical cell will come with it).

6) remove the rear optical cell (it unscrews). or don't it doesn't really matter.

7) remove these three set screws (only two are actually visible in the photo due to the angle):
http://farm8.staticflickr.com/7243/7078009455_3037934045_o.jpg
8) the aperture mechanism should come free (but may disassemble in the process if you aren't careful).

as far as cleaning it goes everybody has their own methods it seems. i've either soaked them for a bit in a windex dilution or wiped them with alcohol. both seemed to work ok.



Apr 14, 2012 at 06:14 PM
crazeazn
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p.1 #11 · p.1 #11 · fixing a stuck aperture


awesome! this is on my to do tomorrow!


Apr 15, 2012 at 01:48 AM





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