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04-01-2014, 09:35 PM   #1
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JCpenny 135mm f/2.8 aperture issue

Hi folks,
My name's Erik and I'm new to the forum and to Pentax camera equipment.
I was just given a K1000, a ZX-M and several Pentax lenses. I have never shot with Pentax though I remember my dad having a few when I was growing up and learning photography. I have recently been wanting to get back into shooting film, so I acquired this gear at just the right time. Along with them, I received a JCpenny 135mm 2.8 lens. After looking around the web, I see several lenses like this one and it seems that the majority have a 55mm filter thread, mine has a 52mm thread. Anyway, it appears that the aperture ring is not engaging the iris. It will move and click home at all the apertures but the iris is not closing. (it seems to be stuck at f/2.8). Does anyone have any experience with this lens or could shed some light on this for me?
Thanks in advance,
-Erik-

04-02-2014, 08:24 AM   #2
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Do you have a picture of it? I saw one on eBay that looks a lot like my Sears 135mm "Macro Zone", but without the macro feature. It was made in Korea.

Sometimes if I store mine at f2.8 the aperture gets stuck wide open. I can usually get it working again by setting the aperture ring at f22 and jiggling the aperture lever, but sometimes it needs a gentle smack to the barrel with the palm of my hand. It usually keeps working for a while after this so I haven't bothered to tear into it and find the cause.

If it still doesn't work then it could be oil on the aperture blades. It would be better to just find another lens unless you are really adventurous.

Last edited by elliott; 04-02-2014 at 11:29 AM. Reason: f22, not 2.8
04-02-2014, 08:52 AM   #3
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Do not think you should put oil in the leaflets of the diaphragm, this makes sticking worse, for me, you should try to get to them and clean them with isopropyl alcohol purest you find it. Do this with cotton tips carefully and lots and lots of patience. I have done that and works
04-02-2014, 09:00 AM   #4
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QuoteOriginally posted by fireman4792000 Quote
you should try to get to them and clean them with isopropyl alcohol purest you find it. Do this with cotton tips carefully and lots and lots of patience. I have done that and works
Naptha (lighter fluid) works better and can be easier to find locally than 99% alcohol.

04-02-2014, 11:14 AM   #5
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The lens has a lever sticking out of the back. If you hold the lens so the back element is facing you, the lever is about 90 degrees clockwise* from the alignment dot on the mount. The lever may have a more direct connection to the blades, so if you set the aperture ring to f22 and move the lever up and down, the blades might move into view. The most likely reason for them to be stuck is oil, so look for them to be shiny. Cleaning the blades is not a big deal but they are right in the center of the lens so getting to them means taking it apart a lot, probably figuring out how on your own, maybe getting some screwdrivers and the naptha.

You can get something equivalent for less than $50 - SMC Pentax-M 135mm f3.5, Takumar Bayonet 135mm f2.5, Sears 135mm f2.8, or a few more.

*I tried to explain this without using analog clocks, but it got complicated.
04-02-2014, 02:36 PM   #6
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QuoteOriginally posted by Just1MoreDave Quote
The lens has a lever sticking out of the back. If you hold the lens so the back element is facing you, the lever is about 90 degrees clockwise* from the alignment dot on the mount. The lever may have a more direct connection to the blades, so if you set the aperture ring to f22 and move the lever up and down, the blades might move into view. The most likely reason for them to be stuck is oil, so look for them to be shiny. Cleaning the blades is not a big deal but they are right in the center of the lens so getting to them means taking it apart a lot, probably figuring out how on your own, maybe getting some screwdrivers and the naptha.

You can get something equivalent for less than $50 - SMC Pentax-M 135mm f3.5, Takumar Bayonet 135mm f2.5, Sears 135mm f2.8, or a few more.

*I tried to explain this without using analog clocks, but it got complicated.
All of these comments and finally one that asks the obvious question first. "Have you tried the actuator lever?" Thanks Dave for bringing the troubleshooting flow back to center.


Steve
04-02-2014, 02:47 PM   #7
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QuoteOriginally posted by stevebrot Quote
All of these comments and finally one that asks the obvious question first. "Have you tried the actuator lever?" Thanks Dave for bringing the troubleshooting flow back to center.
I mentioned the lever in the first post, but if you have to move the lever to get it to stop down then something is wrong. The lever opens the aperture. Something is wrong with my Sears 135, but it isn't bad enough for me to care.
04-02-2014, 04:41 PM   #8
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QuoteOriginally posted by elliott Quote
Do you have a picture of it? I saw one on eBay that looks a lot like my Sears 135mm "Macro Zone", but without the macro feature. It was made in Korea.

Sometimes if I store mine at f2.8 the aperture gets stuck wide open. I can usually get it working again by setting the aperture ring at f22 and jiggling the aperture lever, but sometimes it needs a gentle smack to the barrel with the palm of my hand. It usually keeps working for a while after this so I haven't bothered to tear into it and find the cause.

If it still doesn't work then it could be oil on the aperture blades. It would be better to just find another lens unless you are really adventurous.
Here are a couple of shots of the lens. Like yours, it is made in Korea. I tried setting it to F/22, jiggling the aperture lever and tapping it, all to no avail.

---------- Post added 04-02-14 at 04:54 PM ----------

QuoteOriginally posted by Just1MoreDave Quote
The lens has a lever sticking out of the back. If you hold the lens so the back element is facing you, the lever is about 90 degrees clockwise* from the alignment dot on the mount. The lever may have a more direct connection to the blades, so if you set the aperture ring to f22 and move the lever up and down, the blades might move into view. The most likely reason for them to be stuck is oil, so look for them to be shiny. Cleaning the blades is not a big deal but they are right in the center of the lens so getting to them means taking it apart a lot, probably figuring out how on your own, maybe getting some screwdrivers and the naptha.

You can get something equivalent for less than $50 - SMC Pentax-M 135mm f3.5, Takumar Bayonet 135mm f2.5, Sears 135mm f2.8, or a few more.

*I tried to explain this without using analog clocks, but it got complicated.
Looks like I may have to take it apart. I'm not too worried about it as I have nothing invested in the lens, at best I'll fix it and at worst I'll at least have a learning experience.

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04-02-2014, 05:24 PM   #9
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The rear half looks just like mine, only without the macro setting on the front half. The macro version just moves the front element forward to allow closer focusing, which results in terrible image quality for macro, but a neat glowing soft focus effect. It is a decent lens though, mine is nice and sharp when not in macro mode and the coatings are pretty good for the age of it.

I'll pull the mount off mine and see if I can see what causes it to bind and might have some tips for you.

---------- Post added 04-02-14 at 08:47 PM ----------

Here it is with just the mount removed, only removed the 4 screws and pulled the mount off. There is no trick to it, it comes off easy. I circled the area displayed in the second picture.


I was able to induce sticking with the lens set at f22 and this is what I noticed. The lever towards the left with the spring on it is fine, the one with the arrow drawn to it is not supposed to be at that position at f22. If I poke that lever in the direction the arrow is pointing the lens stops down as it should.


To actually fix this problem permanently I'll have to tear down the lens further and I'm not sure if I will. This might point you in the right direction though, you should be able to force the aperture closed with that lever and see if it is sticking due to oil on the blades or something binding in the mechanism like mine.
04-02-2014, 07:29 PM   #10
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QuoteOriginally posted by elliott Quote
The rear half looks just like mine, only without the macro setting on the front half. The macro version just moves the front element forward to allow closer focusing, which results in terrible image quality for macro, but a neat glowing soft focus effect. It is a decent lens though, mine is nice and sharp when not in macro mode and the coatings are pretty good for the age of it.

I'll pull the mount off mine and see if I can see what causes it to bind and might have some tips for you.

---------- Post added 04-02-14 at 08:47 PM ----------

Here it is with just the mount removed, only removed the 4 screws and pulled the mount off. There is no trick to it, it comes off easy. I circled the area displayed in the second picture.


I was able to induce sticking with the lens set at f22 and this is what I noticed. The lever towards the left with the spring on it is fine, the one with the arrow drawn to it is not supposed to be at that position at f22. If I poke that lever in the direction the arrow is pointing the lens stops down as it should.


To actually fix this problem permanently I'll have to tear down the lens further and I'm not sure if I will. This might point you in the right direction though, you should be able to force the aperture closed with that lever and see if it is sticking due to oil on the blades or something binding in the mechanism like mine.
`

Here is that same lever on mine (blue arrow). I has about 1/8" of travel if I nudge it with the tip of my screwdriver. The lever with the red arrow moves in conjunction with the aperture ring. I have moved both manually and the iris still does not move.
BTW, i appreciate you taking the time to help me with this.
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04-02-2014, 07:53 PM   #11
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Does the black half circle lever that meets the lever of the mount move freely?

At f22 that lever you have the blue arrow pointing to should be much further over to the left, it shouldn't be visible. I'm pretty sure that one is directly connected to the aperture blades. If you can't get it to move more than 1/8" it looks like you're going to have to go deeper.
04-02-2014, 08:18 PM   #12
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QuoteOriginally posted by elliott Quote
Does the black half circle lever that meets the lever of the mount move freely?

At f22 that lever you have the blue arrow pointing to should be much further over to the left, it shouldn't be visible. I'm pretty sure that one is directly connected to the aperture blades. If you can't get it to move more than 1/8" it looks like you're going to have to go deeper.
I finally gave the small lever a little more than a gentle nudge and got it to stop down. This is what I've got. Looks like there is pretty good build up of oil on the blades as suspected. They are very stiff and once I have it stopped down, it will only open it up once. Now I have to figure out how to get deeper into the lens.
Again, I thank you all.
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04-02-2014, 08:32 PM   #13
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Yep, can't be of much help to you there, I'm definitely not going that deep into mine. You might be able to pull out that rear element easily and wash the blades with some naptha without disassembling everything. I use Ronsonol brand lighter fluid.

Excuse the terrible phone picture, but here is an optical diagram from the owners manual of the Sears version. Very simple 4 element design.
04-02-2014, 08:34 PM   #14
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eherrmann

Clean it with lighter fluid if you do not get pure isopropyl alcohol. do it with a cotton Cutex very careful not to bend Good Luck
04-02-2014, 08:54 PM   #15
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Thank you all for the advice and info. I will probably try to dig into it a little deeper over the weekend. I'll keep you guys posted...
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