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Classic Camera Repair » Maintenance & Repair » Canon fd 400mm 2.8 l chrome breech lens mount bent??? « Previous Next »

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Christi_l
Tinkerer
Username: Christi_l

Post Number: 1
Registered: 08-2010

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Posted on Thursday, August 26, 2010 - 10:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I have an canon 400mm. I was shooting the other day and one of the tripod legs gave way. It fell to the ground and the camera attached took the blunt force. The camera is broke and in very bad shape. After looking at the lens the only damage is to the chrome metal breech lock. It bent as the camera separated from it. The dust cap will not go on smooth and so the metal ring will need to be replaced. I am asking for your help in letting me know if this is major or minor and how you would recommend me to proceed. All your help is greatly appreciated...
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Glenn
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Username: Glenn

Post Number: 832
Registered: 07-2006

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Posted on Thursday, August 26, 2010 - 01:21 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

To replace the 'chrome' breech ring is very simple - Just remove the slot headed screw that is seen in the ring serrations and then unscrew the ring from the lens mount. If the breech ring lock indent engages place a rear cap on the lens before unscrewing the ring, the cap will push the indent out of engagement. Be very careful in removing and tightening the slotted ring retaining screw, they are very soft and strip/break very easily. Use a screwdriver that fits the slot properly.

You will be able to get a replacement breech ring off a scrap lens of any focal length - try your local repair shop or in last resort eBay for an optically damaged f1.8/50mm.

To replace the ring just screw it back onto the lens for a couple of turns, then place lens onto the camera mount and fully tighten up the ring. With the lens securely mounted place the ring retaining screw back into the hole in the ring and remove lens before gently tightening the screw fully. I use an old mount that I removed from a body to allow adjustment of the breech ring, it being easier to handle just the lens rather than lens + body on the bench, but you can use an extension tube for the same purpose if you have one.

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