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06-08-2010, 08:26 AM   #1
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SMC 28mm f2.0 - aperture stuck. HELP!

Hi everyone,

I'm totally new here on the forum, and am in need of some advice.

I just recently purchased a SMC 28mm f/2.0 lens on ebay, almost mint condition. I now realize this is a pretty rare lens, and can hardly find any info about it on the web.

I purchased this lens of use on my Canon 5D mark ii, mainly for video.
SO, this will probably make all you film users pain, but i cut off the aperture lever, and sanded down the plastic guard so it could clear the mirror. I was really nervous doing it, but i found a guide of how to do it and followed the directions.

The lens now fits, and looks BEAUTIFUL with the Canon 5D.

I normally shoot wide open, but today i just realized that when i turn the aperture ring, the iris actually doesn't respond. I can take the lens off, and just a bit of the lever is sticking out, enough for me to use my finger to manually make the iris open and close, but the ring doesn't work anymore. Sad.

Before i modified the lens, everything was working fine. Even though i cut of a few cm of the aperture lever, i don't think that should have stopped it from working right?

another problem is that i can't go diagnosing what's wrong, because one of the screws is stripped on the lens, so the metal plate can't come off. Anyone know how to get a stripped screw head out? its SO small.

Any ideas how to solve this?
here's the directions i followed to get an idea. mine looks the same

How to modify K-Mount lenses to fit a full-frame Canon camera


thanks so much!

06-08-2010, 08:29 AM   #2
Ira
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Boys...be nice.
06-08-2010, 08:40 AM   #3
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oh, and in case this info helps. I can manually set the aperture to f/22, and then the ring works all the way to back to f/2, but then it doesn't work the other way.
06-08-2010, 08:44 AM   #4
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Oh wow... that's one way to obliterate money real quick.

No idea how to fix the problem but you don't seem to have desecreted the lens in vain because that video is quite nice. Still sacrilege but it cannot be helped now.

06-08-2010, 08:56 AM   #5
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Crap like this makes me want to take a sledge hammer to a Canon rangefinder.
06-08-2010, 08:58 AM   #6
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QuoteOriginally posted by natedog23z Quote
Any ideas how to solve this? ... thanks so much!
Sorry I can't help with your repair, but thank YOU for slightly increasing the market value of my A28/2.0 lens.
06-08-2010, 09:12 AM   #7
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A 55 1.8 people can almost understand, but not THAT lens.
06-08-2010, 09:18 AM   #8
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You can't be serious. You just destroyed a stellar Pentax lens and you want help on a Pentax forum?

You should have just bought a Sigma 28 f1.8 in Canon mount instead.

06-08-2010, 09:56 AM   #9
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QuoteOriginally posted by Ira Quote
A 55 1.8 people can almost understand, but not THAT lens.
or an M50/2. I just can't understand people destroying such lens, especially those extremely rare, with value and great reputation. that's a great lens wasted and out for the dumpster.
06-08-2010, 10:01 AM   #10
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QuoteOriginally posted by Ira Quote
Boys...be nice.
c'mon IRA. you know for sure doing such a thing, desecrating and destroying a lens with a high reputation is unforgivable. :ugh:
06-08-2010, 10:16 AM   #11
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Yeh I’m not sure if I should laugh or cry! (Especially if it was the “K” version.)

Are Canon lenses that bad that people have to castrate Pentax ones to use on a Canon body?

Phil
06-08-2010, 10:17 AM   #12
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QuoteOriginally posted by natedog23z Quote
SO, this will probably make all you film users pain, but i cut off the aperture lever, and sanded down the plastic guard so it could clear the mirror.
Guys, he probably never realized the lens could be used as-is on any Pentax DSLR. Can this be considered "attenuating circumstances" ?
06-08-2010, 10:32 AM   #13
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Well, the mutilation has already happened, so we could just as well help him now (and I believe he got confused by the fact that Canon f*cked its users in the ass in the FD>EF transition period, and he probably thought that Pentax did the same to its users).

Anyway: a Pentax K mount lens is closed by default (the diaphragm is spring-tensioned). The diaphragm lever is only used to open the lens to its working position. I think the OP somehow managed to de-attach the internal spring.
06-08-2010, 11:21 AM   #14
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guys guys...i know understand why your mad, but i didn't know what kind of rare lens i had on my hands. I just was trying to save money, and wanted a nice fast wide angle, without having to spend $1,200 bucks. Then when it didn't fit, and i already spent the money, i found those instructions and went for it.

I thought it would fit without having to modify the lens, but turns out it fits on only cropped sensors, not the full frame.

The video is quite stunning, so I'm still happy because that's all i'm using it for. BUT sometimes the f/2 is too shallow, and i want to be able to change it.

Asahiflex, is it possible to get this spring back on?
is there any repair place that i can send this in?

again, if i knew what i had in the first place, i wouldn't have modified the lens.
06-08-2010, 11:53 AM   #15
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Canon has an EOS 28 f1.8 themselves for around $450. You could have resold the Pentax lens for nearly that much. What did you pay for it in the first place? I know it is all water under the bridge for you but jeez that is bad karma slicing up a lens like that. Especially one that is in great shape for starters.
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