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Giuliano Pochini
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 24, 2006 - 03:52 pm: | 
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I have a standard lens FDn 50mm f/1.8 which has moisture inside. The mist (and very slight fungus traces I think) seems to lie on the inner surface of the first element. I already tried to keep the lens in a box with a big silicagel bag in a warm place for several weeks, but it didn't help.
I wonder if this kind of problem can be easily fixed. I read the Rick's guide, but it is about the older breech-lock version of the lens. Well... I couldn't remove the black "canon" ring. Before I try the universal repair tool (1Kg hammer) I would like to know if there is a better way to open it  and what tools do I need to remove the first element. TIA |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 25, 2006 - 08:44 am: |
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Front group removal is very easy on this lens. Using a broadish thin blade and a pad of lens tissue/lens cloth to protect lens, pry off the front name ring. It is glued on with 2/3 spots of Canons 'Diabond' adhesive, just use a gentle twisting action. Remove the three screws that retail the filter/bayonet ring in place and tip out the front group.
The rear group is held by a push on plastic retainer. This was secured by two dabs of Diabond when lens was manufactured - adhesive may be missing if lens has been serviced and I never both to 'glue this retainer back; never had one come loose on me after a service.
To remove rear group you have to remove the three screws that retain the stainless mount bayonet ring. Note these screws are tight and require a well fitting +point driver, anything less will leave you with damaged screws that require drilling out. I use a screwdriver with the grip enlarged with epoxy putty so I can apply the torque, just for removing the mount screws. Been there, cocked one up - never again. You can then lift the ring and the rear mount plate out. The ring holding the lock button is next removed by undoing the three screws, note that these can be of differing lengths. The plastic retainer is now exposed. Keep the lens front down so that the aperture ring etc does not get displaced.
If you have trouble getting the rear mount plate back on, contact me direct and I will send you detailed instructions. Basically if you fiddle about long enough it all clicks into place. |
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