Stuck Diaphragm on Canon 50mm F:1.2

[Paul C. Perkins MD]

Actually - I have two of these lenses - and both are seized at around F:5.6. They focus OK - but BOTH went down in the same fashion within a week of each other.
I tried doing a search under "Canon Lens Repair" and came up with 8 pages of stuff (however interesting) that had absolutely nothing to do with where I might send these two beauties.

Does ESSEX do a good job with these optics - or can someone out there suggest a better place?

TIA

Paul

 

[Mackinaw]

You could probably do it yourself if you're so inclined. The Canon 50/1.2 is pretty easy to take apart, from either the front or rear.

If you would rather send it out, DAG, Sherry Krauter, John Van Stelton and Ken Ruth are other people I would recommend.

Jim B.

 

[Gary B]

Canon 50 f1.2

Canon 50 f1.2

ESSEX CLA mine and had it back to me in less than 2 weeks. About $90.

Good luck


GaryB

 

[Paul C. Perkins MD]

Gary,

I picked the SN#33309 lens to send to ESSEX today. Next month is Leica month - and while I have a 50mm F:2.0 Summicron available - I'd really rather have the Canon. . .

If that is your 19mm Canon on a Leica CL - I am a little jealous. . . ;-)

I have a 15mm Voigtlander and a 25mm F:3.5 Canon - so I don't REALLY need a 19mm Canon . . . I'd ask how good it is - but I expect it is GREAT.


<<ESSEX CLA mine and had it back to me in less than 2 weeks. About $90.
Good luck - GaryB >>

 

[ChrisN]

I'm sorry I missed this last week. If the aperture ring won't move it means the grease has solidified, and needs to be cleaned out and replaced. If the ring moves freely but the iris does not change, that probably means the forked bracket is bent away from the pin - see attached pics.

To remove the lens from the focusing mount, unscrew the collar that surrounds the rear lens element. The focusing mount then lifts off the lens - just lift it away keeping it square with the body of the lens.

To clean out the old grease you need to remove the spring and the tiny ball bearing that form the detent, as well as the forked bracket. Be careful with that tiny ball bearing. Then the aperture ring can be lifted off. Clean and relube with a very small amount of light grease. Lubing mine made adjusting the aperture much easier.

If the forked bracket is bent away from the pin, you should be able to just bend it back.

If the iris won't move even after the aperture ring is removed, it needs specialist help.

When reassembling, put a little dab of grease on the ball bearing to make it stay in place while you position the spring and tighten the two screws.

When you put the focusing mount back on the lens, be aware there is a tab on the focusing mount that has to be lined up with a slot in the body of the lens.

 

[ChrisN]

One more pic (max three per post is frustrating!).

 

[Gabriel M.A.]

ESSEX CLA mine and had it back to me in less than 2 weeks. About $90.

Ooooh! That's nice to hear. Where are they located?

 

[JasonC]

Essex is in New Jersey.

http://www.essexcamera.com/

Jason.

 

[Paul C. Perkins MD]

Chris,

Thanks for the posts.

I've disassembled (probably) both lenses to address clouding of the inner element (s) - but the idea of goining any further . . .

I figure if someone else does a repair involving major disassembly of a high speed 50mm lens - and it doesn't focus when I get it back . . . well . . . I can always send it back.

Paul

 

[rogue_designer]

Not a good month for 50 1.2's - my iris just seized as well.

I have no intention of cracking open my favorite lens myself though - off to Essex it is!

 

[jlw]

I'm sorry I missed this last week. If the aperture ring won't move it means the grease has solidified, and needs to be cleaned out and replaced. If the ring moves freely but the iris does not change, that probably means the forked bracket is bent away from the pin - see attached pics.

Nice clear description, Chris! Canonistas might also want to note that the 50/1.4 and black-and-chrome 50/1.8 come apart almost exactly the same way, and also are liable to the Curse of the Horrid Yellow Grease.

 

[Jungle Jim]

Sent mine in for a CLA right after I bought it to John Van Stelton at Focal Point Lens. He did a great job and it took about 3 weeks, including shipping. Price was $125 if I remember correctly.

 

[rogue_designer]

ChrisN - thanks for the pics and the walkthrough.

My 1.2 had some brass retainer clips at assorted points, but easy enough to remove.

As it turns out, the iris siezed, not due to grease (which I cleaned anyway) but because one or two blades had come out of their pivots, and were locked.

So I had to pull out all the iris blades, clean them, check to make sure they weren't bent horridly - then figure out how to replace them (a fun process, I assure you - next time it goes to DAG).

But I had a morning to kill - and that did it.

Got the whole shebang reassembled (the most time consuming part after the iris blades - trying to get tiny screws back in place). We'll see how it holds up. Currently it's smooth as silk. I'll keep my fingers crossed that whatever caused a blade or two to come out of its pivot was an isolated incident.

Cheers!

 

[fbf]

Any experience of opening up the 50/1.4 LTM ? I am trying to clean the rear element but after unscrewed the two tiny screws of the mount base, I have no clue how I should proceed...

 

[rogue_designer]

fbf - it *should* open the same way ChrisN's images of the 50 1.2 opens. Their construction is similar. Remove the rear element retaining ring, and lift the focus helical off.

 

[ferider]

Like Rogue said. 1.4 and 1.2 disassemble identically.

Roland.

 

[fbf]

Thanks. I will give it a try tonight. The little spot on the rear element is really bothering me though it doesn't affect image quality in any way.

 

[raid]

I am awaiting a Canon 50/1.4, and this thread has lowered my "expectations" a little. I hope that the lens will be OK.My 50/1.2 is doing well after several years of use. DAG once adjusted the glass elements and cleaned it from inside.

 

[harry01562]

Raid---
If DAG worked on your lens awhile back, you are probably good for at least 25 more years!! He almost certainly cleaned up the old grease and relubed it when he did the adjustments. With modern lubricants, these lenses should perform well past most of our lifetimes.

If you do have a problem with the 1.4, it could be a DIY project. It is a relatively simple lens, and not prohibitively expensive if you do send it out.
Meanwhile, it is worth it, as it's one fine optic.

Harry

 

[raid]

Raid---
If DAG worked on your lens awhile back, you are probably good for at least 25 more years!! He almost certainly cleaned up the old grease and relubed it when he did the adjustments. With modern lubricants, these lenses should perform well past most of our lifetimes.

If you do have a problem with the 1.4, it could be a DIY project. It is a relatively simple lens, and not prohibitively expensive if you do send it out.
Meanwhile, it is worth it, as it's one fine optic.

Harry

Harry,
Thank you for this good tip. I sent DAG the lens because of focusing problems, and he mistakenly first cleaned the lens. Later, he adjusted the lens.