# Solved: Canon Lens Repair



## Guyzer (Jul 3, 2004)

Ok all you camera buffs I have a big problem. My Canon EF 75-300mm f/4-5.6 III USM has dust right behind the first lens and I need to get it apart. I'm posting 2 pictures and maybe you can assist. Pic 1 shows the lens as it is supposed to be. Pic 2 shows that I have removed three screws and taken off the ring. Here's the problem. Beneath the ring are three more phillips head screws that are holding another ring in place that holds the lens down. When you turn the screws, all of them, it's like they are not attached to anything. They just spin around. What's the secret to getting them off?
PS: once I get it apart and cleaned I know what I have to do so the dust does not get back in. Cheap lens... grrr


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## hewee (Oct 26, 2001)

http://72.14.207.104/search?q=cache...ml+Canon+Lens+Repair&hl=en&gl=us&ct=clnk&cd=2

http://www.google.com/search?hl=en&q=Canon+Lens+Repair&btnG=Google+Search


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## Guyzer (Jul 3, 2004)

Thanks for trying Harry but those links don't help. I've googled this thing to death and can't find how to get those screws out that's why I posted here. I've got my fingers crossed that buck will come along and post this at his other site. ( wink )


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## buck52 (Mar 9, 2001)

Do they need to come out or just turned like a quarter turn, or the like, so the element can be removed?


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## Guyzer (Jul 3, 2004)

buck I don't know. That's what I can't figure out. They look like a screw but they are not. They just spin around. I thought the might have been spring loaded and if pulled out I would be able to lift off the retainer and remove the ring but that didn't seem to work either. I'm usually real good at mechanical things but this has me stumped. It's probably something simple but it's beating the dickens out of me. If I could find a repair manual on line that would help but hours of searching produced nothing. I need someone that has taken one apart to tell me what the secret combanation is.


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## xgerryx (May 16, 2003)

Is there any chance this could be covered by warrantee. If its only a few months old and dust is getting in, maybe it has faulty seals or whatever barrier it uses to keep dust out.


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## Guyzer (Jul 3, 2004)

It could be Gerry but I don't have the time or desire to take the 3 or 4 hours needed to run it into a area where the warranty depot is located. I'm in the process of selling the lens as well as others so I can go out and get my much desired IS models. Time is a big factor here as I won't get another day off other than Sunday for at least 3 weeks and dust in a lens is a issue in trying to sell a lens.


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## linskyjack (Aug 28, 2004)

If its under warranty you can mail it into one of the service centers---I'm not sure if its worth your time.


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## Guyzer (Jul 3, 2004)

I called the closest warranty centre and tried to see if they would commit to the repair being covered and of course they wouldn't but they did elude to the fact that there are ways to make it happen. It's not a money thing as the lens only cost $270.00 cdn but I can get $100.00 on a trade or a few bucks more if I sell it and who likes to throw money away. I don't have the time to run into the city to drop it off so my curious side will have me making more attempts to figure the dismantling out. In the end it may be worth the 100 bucks. I can remember a few of my parents clocks that never got put back together.


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## telecom69 (Oct 12, 2001)

Having this problem would drive me to desperation as well  I know I would be thinking about it at odd times all the while  this is one thing you may well have to admit defeat on though,because as you well know these are precision made and need specialist treatment....I wish you well with this but if you want it fixed then it will have to go back for repair Im thinking...I dont know if you have read this thread below but its the best I have come across on the subject http://photography-on-the.net/forum/archive/index.php/t-29917.html

Wish you well in your quest


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## erick295 (Mar 27, 2005)

There is very little chance that you are going to be able to disassemble and reassemble this lens without introducing even more dust, or worse. The single worst thing you can do to a lens aside from running over it with a truck is opening it at home. Unless you want a $270 paperweight, I'd make that drive.


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## Guyzer (Jul 3, 2004)

telecom I appreciate the feedback and read the link in it's entirety. What can I say except some of it makes perfect sense and some doesn't. It's a cheap lens and my problem doesn't go very deep. The dust is between the first and second lens and may well have been there since new. I take real good care of my stuff and am very diligent about it's environment but this is bugging the crap out of me as it's worthless to a buyer if seen, and it will be seen. If I was buying a used lens I wouldn't purchase it if I saw dust. That said, it doesn't cause any problem with pictures and I could leave it alone thus ending up with a paper weight. The part in the link that doesn't make sense is the use of gas inside the lens. I agree that's possible in a higher end lens but trust me when I say that's not the case with mine. I have been able to us a can of compressed air to blow the dust off the inside of the lens and it's now laying on the inside side portion so I know it's not a sealed unit. I don't want to dismantle it entirely so I know the focus mechanism won't be bothered, all I need to do is get the front lens off. Grrr


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## Guyzer (Jul 3, 2004)

Solved my problem and sold the lens.


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## hewee (Oct 26, 2001)

Good to hear.


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## telecom69 (Oct 12, 2001)

And here was me waiting patiently to hear how you finally did it  think you did the right thing though,glad it worked out for you :up:


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## Scotsguy (Mar 21, 2007)

I've just found the old thread relating to your problems with a Canon EF 75-300 lens. I have exactly the same problem and it's driving me mad! Please, please tell me how you solved your problem!
Regards,
Scotsguy


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## Guyzer (Jul 3, 2004)

I sold the lens and that took care of the problem. I never did get it apart.


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## Scotsguy (Mar 21, 2007)

Ok. Thanks for letting me know.


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