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Thamnophis
Tinkerer
Username: Thamnophis
Post Number: 1
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 23, 2013 - 10:57 pm: | 
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I read through some very good online instructions for taking this lens apart, but can't get the rear lens assembly out. I see the little notches for the lens wrench but am afraid I'll just strip those and scratch the lens up doing so.
Does the rear lens screw out? If I can get it off, are there two lenses more or less stuck together? Maybe the little bit of fungus and haze is stuck between these two lens elements and I won't be able to get at it anyway?
Obviously, I'm new to this! |
Thepurush
Tinkerer
Username: Thepurush
Post Number: 83
Registered: 01-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 23, 2013 - 11:51 pm: |
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The rear assembly consists of a outer tube inside of which 3 elements are aseembled. Do not bother to remove the outer tube since this is screwd to the main barrel and its position adjusted to get infinity and then locked with glue. But you can remove all 2 elements and clean them. Remember the orientation of the spacer between the two. The inner most element is glued to the tube, so the rearr surface is accesible after removing the 2 removalble elements. And the front surface of this is accsessible only thru the front and that too thru fully open diagphram. Remember the Inner most one is madeup of 2 parts cemented together. |
Thamnophis
Tinkerer
Username: Thamnophis
Post Number: 2
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 09:37 am: |
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Thank you so much. SO that means I need to use that darn lens wrench? I've tried with my fingernails, since this way is less likely to scratch and strip those small slits! |
Fallisphoto
Tinkerer
Username: Fallisphoto
Post Number: 311
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 01:00 pm: |
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You can grind the tips of the lens wrench to get a better fit, but yes, you are going to have to use it. |
Fallisphoto
Tinkerer
Username: Fallisphoto
Post Number: 312
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 01:11 pm: |
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Oh, one more thing. When it comes to removing the fungus, I believe the best thing is a 50/50 mix of grocery store ammonia and drug store hydrogen peroxide. Most of the so-called "cures" for lens fungus you find on the web will kill it, but they won't remove it. Those filaments of fungus are VERY hard to remove and you can scrub at them for hours with very little effect. Many people just assume their lenses are etched and give up. The aforementioned mix will dissolve the filaments and remove them. |
Thamnophis
Tinkerer
Username: Thamnophis
Post Number: 3
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 01:31 pm: |
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Thats helpful, thank you. Is it likely, or even possible that the fungus is between the lenses that are glued together? If so, I assume there is nothing to be done about it?
By the way, following the illustrated guide I found online, I was able to remove the aperture intact with the housing. I have it soaking in 70% Isopropyl alchohol now. But will this dissolve the oil on the blades, or will I have to do some additional wiping (god forbid :-)
Assuming I can just let it soak then air dry, how long would a typical soak take?
Sorry for the questions. This stuff must seem trivial to most of you! |
Thamnophis
Tinkerer
Username: Thamnophis
Post Number: 4
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 01:47 pm: |
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Thanks for the fungus removal suggestion. If I get the rear lens elements out I'll give it a go.
Curious if anyone has tried the oxygen cleaners on lens fungus? Its used in bars to clean the keg tubes/lines and dissolves most anything organic. I use it to clean hardened gunk on the inside of wine carboys that I can't reach to scrub. |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 106
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 02:57 pm: |
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I think the 50/50 solution recommended is good. I've tried alcohol on fungus and it just kills (for a while) and doesn't remove much. Thanks Fallisphoto for that tip.
Someone will likely beat me to it, but naptha is a better choice for cleaning the aperture assembly. Also known as lighter fluid. I spend the slight extra cost and buy Ronsinol brand (I think its spelled Ronsinol). Alcohol doesn't really dissolve and flush away the greasy yuk.
Never tried an "oxygen cleaner". My guess it would kill (or mostly kill) fungus, but not remove much of it.
You're off to a good start. You were wise to get a lens wrench/spanner and use the right tool for the job. Many try to improvise and as a beginner, that often leads to discouragement.
Thamnophis -- Garter Snakes!!! |
Thamnophis
Tinkerer
Username: Thamnophis
Post Number: 5
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 24, 2013 - 06:36 pm: |
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Well, partial success! I managed everything - took me all day - but can not get the rear mount assembly back together. So close, yet...
I'm using this very helpful guide:
http://rick_oleson.tripod.com/index-161.html
But, if I have the aperture selector in the fork, there is no way the AE pin aligns with the hole it belongs in. As I rotate the assembly, the pin pops into a screw hole. Its just a hair off to start, but simply will not drop into place.
I wonder too if I got the aperture housing in correctly. The aperture doesn't seem to close down as far as it should for f/16. But that may be related or not.
(Yes, garter snakes :-) |
Thamnophis
Tinkerer
Username: Thamnophis
Post Number: 6
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 25, 2013 - 03:08 pm: |
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Finally. After too many hours of trying, I got the rear mount back on and working. Eventually I had to open up another Canon lens of the same vintage to see what I was doing wrong.
It was simply a matter of rotating the rear aperture selector once it was in the fork passed the mount lock tab, then aligning and inserting.
These things make Ikea furniture look easy :-)
But everything cleaned up nicely (lighter fluid worked well)and the lens takes nice contrasty pics now. So thank everyone! |
Phaeton
Tinkerer
Username: Phaeton
Post Number: 2
Registered: 03-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 26, 2013 - 09:55 pm: |
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Please update on this thread as and when. I was always told lens fungus created an acid as a biproduct of its spread, and that it was this acid which 'etched' the interior elements of lenses. It would be interesting to know if this was fact or fiction. Also, how did you clean up your lens - after removing the fungus - prior to reassembly? That final clean up must also have been quite challenging, to make sure all the glass was relatively pristine?
Thanks,
P |
