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fd 50mm f/1.4 lens disassembly: haze and oil on diaphragm

H S , Dec 22, 2009; 04:03 p.m.

Hello.

I have this "new" 50mm f/1.4 SSC lens that is showing very slight haze on part of one of the front elements (but I cannot make this out very clearly). I can barely see the haze if I shine a bright light in to the lens or look through it in bright sunlight, and that too if I let the shadow of the hood pass over that hazy part.

Also, there appears to be some oil on the aperture diaphragm making is slightly sluggish (I can hardly make the difference in closing speed, but looks a tiny bit slow compared to a clean 50mm f/1.8 lens I have) when closing during a shot.

I have seen this web page which shows how to disassemble the lens and clean the diaphragm: http://rick_oleson.tripod.com/index-161.html

So, what would the experienced users say regarding the lens. So, should I try and go ahead with the cleaning or try to return it?

Thanks.

Responses


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Stephen Lewis , Dec 22, 2009; 04:13 p.m.

Do you have the proper tools to open it up and the technical skills to put it back together correctly when done, especially if something pops out of place while open? If not, then don't think of opening it up yourself. Would you set your own leg if you broke it? I've opened up lenses before, but not ones which had any value to me....some worked terrific after my "surgery", some just stayed the dogs they were when I got them. I wouldn't personally work on my FD lenses, but Kirons, some of the lenses for the Exaktas, mostly manual daiphragm lenses etc seem easy enough to do....again with proper tools, etc.

H S , Dec 22, 2009; 04:23 p.m.

hmm .. comparing a lens cleaning to fixing a broken leg is just comparing apples to oranges. Extremely poor example for various reasons. Nevertheless, I get your drift.

Tools: not sure about the rubber padded wrench. But other than that, I didn't notice anything special that was needed. Have I missed something?

I am not uncomfortable opening a lens, or anything mechanical, after considering due risks. I have recently opened an AE-1 Program and fixed and calibrated its shutter speed, without really worrying about destroying the camera. I am an engineer, trying to do something like comes naturally to me.

I am basically looking for any advice that can help me decide whether it is worth trying to fix these issues or not. If disassembling the lens is going to throw some crafty nasty surprises, then the risk of destroying it is higher, but the loss is not that great. However, if this is a nasty and frustratingly tricky business, I might not want to spend too much time on it. In other words, if the lens is well engineered and can be taken apart systematically with care and then reassembled properly, then I am all for it.

Alan Swartz , Dec 22, 2009; 05:32 p.m.

H S,

Of course we have to give all the warnings about the risks, but we are all different. Some will refrain from going in, others of us will wade in carefully and not drown. Some will dive in without experience or intuition and ruin a lens.

You'll need some sort of rubber cup to unscrew the name ring, which may be locked with an adhesive. A little appropriate solvent will certainly help with the glue.

If I recall correctly, the front cell can be removed as a unit. I believe it threads in. You'll need a spanner.

I'm working from an old memory here, but I believe that in the SSC 1.4 lens, the diaphragm assembly comes out the front as a unit, held by screws. (I know this is true of the early chrome-front version; I think it was an early 50/1.8 SC where the blades laid in the lens barrel itself.) You of course know to mark relationships as you proceed.

You can flush the assembly with naphtha, but you'll do a better job if you disassemble it and clean the blades individually. I follow the naphtha with isopropyl alcohol for a cleaner finish on the blades. The blades are aluminum. They're springy and tough considering their thickness, but of course exercise care not to damage them.

The only mechanical concern with reinstallation is to make sure the cam follower down in the barrel fits properly into the back of the diaphragm assembly. While some say that no adjustment is necessary upon reinstallation, I have found that the screw holes are roomy enough to allow a good bit of variation in diaphragm opening. I would meter carefully with the lens before disassembly so that you have a benchmark for resetting the diaphragm. You might want to precisely measure the opening before removal.

You can disassemble the front cell if you want to clean glass. You'll need a spanner for this. It's fairly easy to remove haze, unless it's a coating gone bad, which I think is unlikely in a 50mm. You'll likely end up with more large dust particles than before you started.

In a nutshell, no nasty surprises.

Mark Wahlster , Dec 22, 2009; 05:39 p.m.

" if the lens is well engineered "

ROFLMAO whether or not the lens that was one of the flagship lenses for Canons most successful Professional system was well engineered will not be your problem. The problem will be if you slip or attempt to use the wrong size tool or you get frustrated or you don't have the experience with assembling a lens of this type. Not if Canon did it right.

If you collect up the proper tools follow a good set of instructions and don't loose some tiny screw in the carpet or slip and scratch something then the likelihood of being able to clean a tiny amount of dust and haze off an accessible elements surface is good. Be advised that to do this correctly you will need to remove all of the old lubrication that has gassed off and replace it with a new grease that is suited to the job. To just wipe the blades clean will lead to the moisture returning first time the lens warms up.

You ask about returning it. Did you buy this from a local dealer or eBay or on line dealer? Personally if the lens was not as advertised I would return it.

Mark Wahlster , Dec 22, 2009; 05:40 p.m.

" if the lens is well engineered "

ROFLMAO whether or not the lens that was one of the flagship lenses for Canons most successful Professional system was well engineered will not be your problem. The problem will be if you slip or attempt to use the wrong size tool or you get frustrated or you don't have the experience with assembling a lens of this type. Not if Canon did it right.

If you collect up the proper tools follow a good set of instructions and don't loose some tiny screw in the carpet or slip and scratch something then the likelihood of being able to clean a tiny amount of dust and haze off an accessible elements surface is good. Be advised that to do this correctly you will need to remove all of the old lubrication that has gassed off and replace it with a new grease that is suited to the job. To just wipe the blades clean will lead to the moisture returning first time the lens warms up.

You ask about returning it. Did you buy this from a local dealer or eBay or on line dealer? Personally if the lens was not as advertised I would return it.

H S , Dec 22, 2009; 06:00 p.m.

The option of opening it up and cleaning the blades is definitely there. However, I have noticed this strange thing happening. As I have worked the diaphragm off camera and let it alone for a while, it appears as though the oil on the blades is ... dare I say it ... "lessening". If I were not overly cautious, I might dare and go ahead and say that the liquid appears to be disappearing.

Now I am not sure how to explain this. I will just wait it out a few days to see where this oily thing stands in the lens. It might turn out that I don't have to do anything at all (fingers crossed).

Regarding that little haze, I think I will take shoot a roll and see if it bothers me at all.

H S , Dec 23, 2009; 01:30 p.m.

Mark, by "well engineered" I did not want to question the performance of the lens. What I was trying to point out, if you were to pay careful attention to the context in which that phrase was used, is whether it was engineered keeping in mind the ease of disassembly and re-assembly as well.

Now, I do not have any experience with taking lenses apart, yet, so I could be plain wrong here. But it would be presumptuous of me to conclude just by the performance of a mechanical device, or by it brand name, if its construction kept the aforementioned points in mind. As far as marketing people go, this won't occur to them till the end of time, and these people actually drive many design changes in technological. Go figure! Not to mention the fact that Canon is not infallible by a long shot when it comes to design shortcomings :) Disclaimer: I am a Canon user.

Jeff Guthrie , Dec 23, 2009; 09:14 p.m.

I tried to take apart and clean an old 50/1.4 SSC lens a few months ago, and the results were not so good. A small spring took a leap far over my table and landed in the carpet, never to be seen again. The lens was a freebie, so tossing it in the can wasn't too painful.

H S , Dec 23, 2009; 09:31 p.m.

Jeff, that was unfortunate.

What intrigues me right now is that the liquid smudges I see on the diaphragm appear to be disappearing or evaporating within several minutes. As I work the aperture manually, the blades get this fluid over them in tiny quantities, like very little drops. But as I leave the lens standing for some minutes with the blades in a position where the fluid can be seen, after some minutes that fluid is gone, as if it was never there.

I am not sure if oil on blades is supposed to exhibit this kind of behavior. Can somebody shed some light on what I am observing? I can post a macro photo if that helps.

Thanks.


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