Lens dismantling

Hello,

out of curiousity, I tried disassembling my 50 mm 1.8 II last night. I was able to remove the lens mount but got stuck from there. I can't find any other way to remove the back cover so I can remove the circuit board.

anyone knows a good source for repairing lens?

Thanks,

In the mid 1970's I got a job at a camera store in town and was told about Mr. Jones. Mr. Jones bought a Canon F1 and about eight lenses. His photos were "soft" and since Mr. Jones' ego wouldn't even let him suspect that it might be his fault, he took EVERY lens apart. Then he discovered that he couldn't put them back together.

Off these lenses went to a local camera repair store, whose owner would work on a lens when things got quiet. During my limited time at the store Mr. Jones got one lens back and I assume at that rate that it would be years before they were all returned!

So it's just a thought that maybe it'd be better to leave lens disassembly - and subsequent assembly - to a pro. Besides with the price of a Canon 50mm f1.8, just throw it away and buy another one.

maybe this will help you?
http://f20c.com …st/EF%2050%201.​8%20II.PDF

BTW why are you trying to dismantle it?

well I just like to see what's happening inside the 50 mm 1.8 II. the lens itself doesn't have any problems. i was browsing the internet when i found an article that shows how to disassemble a 50 mm 1.8 mk I. so i decided to try it myself.

i'll post some pics if ever i succeed.

Thanks,

EoSD30fReAk wrote:
maybe this will help you?
http://f20c.com …st/EF%2050%201.​8%20II.PDF

BTW why are you trying to dismantle it?

thanks very much for this manual. i'll give this a try later after work.

I'm dismantling it just for the benefit of the doubt. ever since I had the 24-70, i rarely use this lens so i thought why not do some experiments with it.

Thanks,

Becareful now. There are two different 50 1.8 II's, the new one has the USM motor.

???

no there aren't!!

the only 50mm with usm is the f1.4 ! there's no f1.8 with usm motor.

EoSD30fReAk wrote:
???

no there aren't!!

the only 50mm with usm is the f1.4 ! there's no f1.8 with usm motor.

yep.

Coicidentally i just the other day wrote out these instructions for another forum ,so i'll cut and paste them here. I'll try to add some photo's of the insides as well

1. First remove the two tiny screws that hold the rear electrical contact strip

2. Using a blade knife or similar ,gently lift the cover on top of the lens.Approaching from the rear lift the right side first-it will be glued on with a light contact glue so should lift easily.Note that the focus switch has a small extension inside the lens so the cover will have to be jiggled gently to allow it to come free completely

3. Under where this cover was inside the lens you'll see a screw and small metal tab .This is the stopper that keeps the lens from focussing past infinity. Remove this screw and tab

4. Now you can rotate the focus ring all the way in. You should then be able to remove the whole front/inner assembly from the main body.It will probbably need to be wiggled abit.

Be sure that the rear electrical strip comes out with this assembly.It may need abit of a push
Now you will have the inner assembly which has a relatively large plastic focus ring sitting loosely around it. What happens next is that the front lens group comes out the front. It's held in place by four plastic clips,one of which is glued with a tiny tab (on mine at least,i'm not sure if all lenses have it).
I'll try to post a pic of these tabs.

5. Basically all you do now is remove that glued tab and force apart the front and rear groups. You'll see where they join because the focus ring has some large pegs that fit in between the front and rear groups. Just use a screwdriver or similar to pop the front part away.
Mark the parts if you like so that reassembly is easier.They can only go together one way but it's simpler if there are marks to guide the proccess.

6. With the front a rear halves seperated the cleaning can be done.There are only two surfaces inside (i.e - the glass elements can't be taken apart any further)
The aperture blades are also accessable if anything needs to be done to them ,like removing oil or similar problems

Putting it all together again is mostly easy. The only tricky bit i can remember is that the rear electrical strip is awkward to get back in due to lack of room .
Use a small amount of contact glue on the side cover
Good luck with it!

If I knew what I was doing, I'd take apart my 70-200L IS. I'd love to see the inside of that thing. I'm sure I could find it on the net somewhere, though.

Pic 1 shows where to lift the access cover.

Pic 3 shows how the insides come out the front of the main body

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Pic 4 shows one of the internal retaining clips that hold the front and rear lens assemblies together. Some of these are visable and some may not be. There should be four of them ,with one having a small amount of glue and a tiny plastic tab holding it.

Once you've removed this tab and glue,just make sure none of the others have similar stuff in them.
The internal clips themselves have a rounded profile so that the assemblies can be forced apart easily. Putting it together is just as easy -just line up the parts and push . They should snap together perfectly.

Pic 6 shows a good place to insert the screwdriver to pry the assemblies apart. I've added some red lines that show the joint line (allthough slightly hard to see)

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Pic 7 shows the main front and rear parts ready to have the lens surfaced cleaned.

The front assembly (on the right) has the focus grip ring sitting loosely around it.

The rear main assembly has a line pointing to a place where you can manually activate the aperture if it needs cleaning. (The aperture assy may be easily removable but i'm not sure -i didn't try )

Just a small note for those that have never done internal lens cleaning before-
MAKE SURE YOU REMOVE EVERY LITTLE SPEC AND SMUDGE ,including tiny fragments of lens cleaning cloths/paper,etc.
Because of the way lenses are made they tend to greatly magnify everything inside the lens elements.
The way i do it is to clean the surfaces properly, then remove every remaining spec one by one. These can be lifted off with a folded/pointed lens paper that has been *slightly* dampened with cleaning fluid.
Do this under a very strong light while tilting the lens various directions so that the specs show up.

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I build computers but I sure won't mess with a lens! Good luck to those that do!

If you send it to me I will dismantle it for you, take photos and post them on the internet, and even email you the URL to find the photos. Problem solved.