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03-06-2010, 04:45 AM   #1
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Broken Lens Aperture

I was just out using my sp1000 when I noticed that the lens wasn't stopping down.
I removed the lens and started pushing the little button and nothing happens.
It appears the aperture is fully open except for one leaf that is partially out. maybe it is stuck. It is an m42 auto 1-1:4 pentax lens.
Is it a linkage that has broken???
cheers
greg

03-06-2010, 04:53 AM   #2
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It sounds like something in the aperture mechanism has come lose and this has caused one of the blades to separate from the rest of the mechanism. This could easily provide enough friction to jam the rest of the blades. Can you provide a photo showing the out of place aperture blade? What is the make / model of the lens? Have you ever done any DIY lens repair before?
03-06-2010, 06:24 AM   #3
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I will get a photo up asap.
Its an original pentax 50 mm 1:1.4 m42, auto super takumar. I purchased thru ebay about 6 months ago.
I have never attempted any repairs myself. Possibly will take it to the local guy for dismantle.
03-06-2010, 07:48 AM   #4
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here's a few rough pix.

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03-06-2010, 08:14 AM   #5
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The apareture blades have two pins in them which locate in holes in a static and a rotating ring in the aperture mechanism. If one of the pins has come out of its hole (quite possible if something has come a bit lose inside) then a blase can get out of place and would appear as in your pictures. As the aperture is closed by the pressure of a small spring, one out of place blade would be quite enough to jam the rest of the aperture (even light iol can be viscous enough to make apertures stick - mine had this problem but workes perfectly now that it is clean).
This should be quite straightforward to fix but if you are not technically minded then I would recommend having it done professionally. It should be quite a quick and simple job and so it shouldn't be all that expensive. This is a good lens and well worth having fixed.
03-06-2010, 08:08 PM   #6
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thx matt,
yes i don't want to practice on this lens so will take it to someone who knows what they're doing.
thx
greg
03-06-2010, 11:06 PM   #7
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THREADJACK!!

I have a non-operational iris on a different lens. My PK-M Vivitar 24/2 (US$100 on eBay awhile back) stays wide open. No clicks when I turn the aperture ring. No blade movement when I move the linkage blade. Now that I think about it, I'll probably contact the nearest repair shop (2 hours away) for an estimate (when they're open, in 36 hours). But since I'm here, I'll ask: does this sound repairable?
03-07-2010, 12:31 AM   #8
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Steve's Digicam Forum posted a few links to highly recommended repair shops for manual lenses. Ralph Ines sounds like the man for you in this case, his rates for manual primes are extremely reasonable, I would even go so far as say cheap.

The cost of this lens is only ~$50-60 on Ebay, well below what the repair/shipping cost would be for broken apertures. However, I'm a proponent of fixing lenses even if it costs more than to buy another one. They've served you well and you should be responsible for them. It's shameful to throw away good lenses. I do hope you bite the bullet and get it fixed regardless of cost. There's no harm in shopping around for the least expensive repair shop though. Best of luck.

03-07-2010, 01:55 AM   #9
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QuoteOriginally posted by hangu Quote
Ralph Ines sounds like the man for you in this case, his rates for manual primes are extremely reasonable, I would even go so far as say cheap.

The cost of this lens is only ~$50-60 on Ebay, well below what the repair/shipping cost would be for broken apertures.
Many thanks!! Ralph Ines sounds extremely reasonable. As for buying another 24/2 PK lens -- I just now searched eBay for VIVITAR 24MM PENTAX and the only hit is for an M42 f/2.8 in the UK for about US$212!!! Of recent sales, there's almost nothing comparable or better. Ralph Ines' quote of US$48 max (w/ return shipping) looks like a real deal.

FOLLOW-UP: So Ralph said the fix would be easy, but advised me to check the rear element for fogging, indicative of glass separation. Dang, there it is. The optics are soft. It's not worth fixing without a rear element replacement, and good rear elements haven't shown up for a long time. Dang. Guess I'll eat worms and die.

Last edited by RioRico; 03-07-2010 at 06:04 PM. Reason: follow-up
03-07-2010, 11:12 PM   #10
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QuoteOriginally posted by RioRico Quote
Many thanks!! Ralph Ines sounds extremely reasonable. As for buying another 24/2 PK lens -- I just now searched eBay for VIVITAR 24MM PENTAX and the only hit is for an M42 f/2.8 in the UK for about US$212!!! Of recent sales, there's almost nothing comparable or better. Ralph Ines' quote of US$48 max (w/ return shipping) looks like a real deal.
Funny you should mention the 24mm Vivitar F2.0. I just received a broken 24mm Vivitar F2.0 with K-Mount on Ebay 2 days ago. The seller failed to mention that the lens had taken a hard fall. The front barrel is completely crooked and the focus ring no longer works (but still turns). I searched and found Ralph Ines when I saw the poor, broken lens. He said that this lens is beyond repair but the lens elements/aperture blades are still perfect. I had paid more than $100 for the broken lens and I've made my mind to return it for a full refund. However, if it's any use to you, I can try to barter with the seller for the broken lens since it is useless to him as well.
03-08-2010, 01:53 AM   #11
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QuoteOriginally posted by hangu Quote
However, if it's any use to you, I can try to barter with the seller for the broken lens since it is useless to him as well.
PM sent. Thanks.
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