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07-27-2015, 07:23 PM   #1
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JCPenney 1:2.8f=135mm Aperture

So I have been picking up some inexpensive lenses to help me identify what I enjoy most about photography, and what sorts of features I want in a lens, before I buy more modern lenses with the much higher price tags. My question pertains to the JCPenney 1:2.8 135mm that arrived in the mail today, for $15 from eBay.

When looking through the lens, there doesn't appear to be a diaphragm to regulate the aperture... I can rotate the aperture ring from 2.8 all the way to 22, but nothing seems to change inside the lens.

View through the lens, at what should be the smallest aperture setting (largest number, 22):
https://farm1.staticflickr.com/353/19447704154_d637a529b9_k.jpg


It was only $15, I can get it to take some nice pictures, and I've recommissioned the nice lens cap it came with for a new life with my new favorite lens (that also arrived today), so I'm not too worried about getting it fixed or anything. (Although if this is something that I could fix, rather than paying someone to do it, I may attempt it at some point).

Mainly I just wanted to make sure that yes, the aperture ring is not functioning correctly, and I'm not crazy. (I'm still new enough to this that it could go either way. )

Sample pictures below, so the lens does work! Mostly.
https://farm4.staticflickr.com/3785/20044067456_b269c71c67_k.jpg
https://farm1.staticflickr.com/413/19883669439_109b7aba69_k.jpg

EDIT: Turned to links due to large file size, don't have the ability to resize them at the moment. Sorry!


Last edited by SolarCat; 07-27-2015 at 07:31 PM.
07-27-2015, 07:30 PM   #2
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Let's see the other side so we can tell you more. Assuming it's a K lens maybe the lever has an issue,or it could be a preset type with 2 aperture rings. I thought those were all M42 screw types but what do I know?
07-27-2015, 07:53 PM   #3
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I am still mastering "photography after dark" so apologies, these are a little fuzzy - but I am hoping they're clear enough to show the lens?



07-27-2015, 08:09 PM   #4
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The camera keeps the lens open for you to see better. It closes to the set aperture when you fire the shutter - or - (try this) check your depth of focus. You need to have a small aperture set to check this of course.

07-27-2015, 08:10 PM   #5
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interested as I have the same or similar lens.....stuck wide open.....good glass and I did get comet 'lovejoy' with it and the o-gps but would like to stop it down....also have a vivitar 28-105 series 1 f2.8 that is stuck open as well that would really be sweet to get fixed!

---------- Post added 07-27-15 at 10:13 PM ----------

QuoteOriginally posted by arnold Quote
It closes to the set aperture when you fire the shutter
I believe that is for A lenses....set to A.....as the aperture thingy has to set to allow for totally manual lenses
07-27-2015, 08:25 PM   #6
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QuoteOriginally posted by arnold Quote
The camera keeps the lens open for you to see better. It closes to the set aperture when you fire the shutter - or - (try this) check your depth of focus. You need to have a small aperture set to check this of course.
I have four other lenses, and with each of those, when I turn the aperture ring I can see the diaphragm moving inside the lens. (Yes, I did notice that they're all wide open when installed in the camera, but I'm talking about holding the lens only in one hand and turning the aperture ring with the other).

I could attempt a video to show this?
07-27-2015, 08:39 PM   #7
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QuoteOriginally posted by SolarCat Quote
(Yes, I did notice that they're all wide open when installed in the camera, but I'm talking about holding the lens only in one hand and turning the aperture ring with the other).
Have you tried flicking the aperture control shut-down lever on the back of the lens?
07-27-2015, 08:41 PM   #8
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QuoteOriginally posted by SolarCat Quote
when I turn the aperture ring I can see the diaphragm moving inside the lens
yes, that's what is supposed to happen

07-27-2015, 08:53 PM   #9
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QuoteOriginally posted by arnold Quote
Have you tried flicking the aperture control shut-down lever on the back of the lens?
I can move it, about a quarter inch or so, with my finger - and the diaphragm still doesn't move from wide open.
If I lightly shake the lens it gives off a soft jingling sound from the ring. (My other lenses also do not do this).

Video of two lenses while D moves the aperture ring for me. The first one is the JCPenney one in question, the second is a well-functioning Sears brand I bought from a forum member here.
https://www.flickr.com/photos/135100033@N02/19885757358/in/datetaken/


From the confusion in some of the replies, I am confident saying that the JCPenney is indeed broken, and stuck at the 2.8 aperture setting, potentially due to bad/old lubricant.


Many thanks for the confirmation!
07-28-2015, 06:49 AM   #10
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I saw this lens at a pawn shop (branded Sears, but I can tell it looked very similar except for the beauty ring on the front). I didn't buy it, it had the same problem. I think it's a common thing with these lenses which as far as I know are made by Samyang. The iris (or the aperture mechanism) just breaks and then it becomes a paper weight - I'm assuming you're not going to spend at least 50 dollars to have a 15 dollar lens fixed. And I don't think you'd want to attempt to disassemble and re-assemble this mechanism.

If you bought it from Ebay and it said it was in working condition, you can probably return it. If the seller sold "as-is" with known or unknown problems, you probably lost your lunch money...
07-28-2015, 08:23 AM   #11
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It was $15 with caps for both ends (so replacements for some nicer lenses), and it takes decent pictures with the wide open aperture, so I'm not worried about it. It will never be my favorite lens or anything, but I can use it.

Is the mechanism very complicated? I've rebuilt engines before (lawnmower, electric drill, etc), but never something this potentially delicate.
07-28-2015, 10:38 AM   #12
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Aperture blades are likely oily

One reason you can pick up such lenses quite cheap is that the aperture mechanisms are the first thing to fail. Oil, or oil percolated off the focusing threads grease, has migrated onto the aperture mechanism, and somehow gets onto the blades themselves. Since the springs that actuate the aperture aren't all that powerful, the sticky blades just stay wide open.
If the lens has some value, it's worth getting disassembled and cleaned. But inexpensive third-party optics are seldom worth the investment. Even trying to fix it yourself requires buying a few precision tools.
Cheaper to just go searching for another one that still works properly.
07-29-2015, 02:37 AM   #13
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I have an old Vivitar zoom that is behaving the same way; it's interesting to hear what the likely cause is.
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