| Author |
Message |
    
Rags Chellam
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 16, 2006 - 03:23 am: | 
|
I have a 300mm/f4 AF D Nikkor with a little fungus just behind the big front element. I have used the right spanner from Micro-Tools but the retaining ring simply does not budge. Any sugestions on how to loosen the ring? |
Rags Chellam
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 16, 2006 - 03:41 am: |
|
I realize that this is a modern lens I am talking about but my question pertains more to a mechanical problem that needs help from seasoned folks from this forum |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 16, 2006 - 09:04 am: |
|
Do not know about Nikkor lenses but my experience with Canon optics may be of use. Obviously the ring has spanner slots. so is meant to come out. Now the important question; does this ring screw down the same set of threads that the filter screws into? If it does, then the ring will most likely be held by sealant/threadlock. On large diameter Canon front glass the retaining ring is threadlocked in place. Thus if a filter bottoms in the threads, the filter ring cannot grab the retaining ring and loosen/back it out.
On my Canon FD optics I use acetone/ketone (as stated in manual) to loosen sealant.
PLEASE NOTE that you must not use these solvents on any plastic components. I have no idea what so ever on your Nikkor's materials of construction, hence I recommend reading the repair manual before going further.
I have seen these rings locked by grubscrews on large aerial reconnaissance lenses. However I have never come across this on small format lenses. |
Rags Chellam
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 16, 2006 - 08:46 pm: |
|
Thanks Glen. Yes, there are two spanner slots and the filter and the retaining ring use the the same 82mm thread. Guess it must be the sealant that is holding it firmly. What is the chemical component of acetone? For what other purposes is acetone used? |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 17, 2006 - 08:18 am: |
|
Acetone is a Ketone. It is used as a solvent for various chemical processes. The next 'common' ketone is MEK - methyl ethyl ketone - this is a very common industrial solvent, adhesive base etc. Canon just state 'ketone' in the manuals and I guess they mean MEK, but acetone works in same manner. Both 'melt' plastics, or should I say 'solvent weld', so as stated do not get near plastics. Delrin, acetals and glass loaded nylons are quite stable and generally a quick wipe does not harm the finish.
I use acetone as a general purpose cleaner because it is miscible with water and thus easily treated as waste. I purchase mine in 2litre bottle from my local chemist - pharmacy.
Depending on the type of sealant used in your lens, you could try the solvent sold to remove Superglue.
Acetone/MEK is used to clean up tools used to lay fibreglass mat/resin mix. So try a boat/auto repair shop or even a good model shop that deals in flying and sailing models - not just plastic kits. It seems that in US (assuming you are in US) your hardware stores tend to sell a greater range of solvents. Here in UK one has to go to more specialised outlets/wholesalers to find some types solvents/cleaners. For instance wholesalers selling/stocking boot and shoe repair requisites are a good source of specialised solvents and contact adhesives.
Some people have used nail varnish remover - these tend to be acetate solvent mixes - but note that they also contain oils to prevent the drying out of the cuticle/skin. |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 17, 2006 - 11:28 am: |
|
Some fingernail polish removers are pure acetone, and generally marked as such; i have a 16 ounce bottle of this .... pretty strong stuff for fingers but oil-free for use as a solvent. Heed Glenn's advice about contact with plastics, though: acetone is nasty stuff to plastics, it dissolves the polycarbonate that most modern camera shells are made of. it's generally safe with delrin, nylon, polypropylene and polyethylene (though the fumes will stress crack low density polyethylene)... but these are not generally the stuff you find in camera bodies and lenses. so if you see any plastic at all in the lens construction i would keep this away from it. |
