| Author |
Message |
    
Viczig
Tinkerer
Username: Viczig
Post Number: 3
Registered: 12-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 21, 2009 - 06:04 pm: | 
|
Hi,
I have the subject breech mount lens in mint cosmetic condition but the focusing mechanism isn't correct. When you turn the focus ring it hits a stop at about 8 foot marking instead of turning all the way to infinity.
Any one have an idea what's wrong and is an easy fix? I've never had a Canon FD lens apart. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 18
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 21, 2009 - 07:51 pm: |
|
So, the focusing ring doesn't turn very far, is that correct? That is, from minimum focusing distance to 8ft, and then stops?
I'm thinking it could be any number of things. Something may have come loose on the inside and is jamming it. A previous owner may have taken it apart and not reassembled it properly. You probably won't know until you tear into it.
The good news is that the breech lock lenses are easier to work on than the New FD ones.
Michael |
Glenn
Tinkerer
Username: Glenn
Post Number: 669
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 22, 2009 - 01:38 pm: |
|
Victor,
You have missed out a very important observation - with the lens on a camera, what is the actual observed focus distance when focus ring is rotated. ie does lens focus to correct minimum and 8ft distances or is lens actually focusing on objects at other distances than scale measurements?
It is years since I stripped an example of this lens down, so I cannot remember the actual construction and fitment of the outer focus ring. It may just be a case of the ring being displaced radially, due to loose retaining screws.
I have a copy of the Canon repair manual for the breech lenses, unfortunately in some respects this publication is even worse than the nFD manual. Not all lenses have a detailed/exploded parts diagram, so if the 135/2.5 is not fully described, I will need sufficient info from you to lead you in the right direction. It is no good just tearing the lens apart, that can lead to even more frustration.
I will not be able to dig the manual out until the weekend; so if you want to PM me with the focus information, feel free - it will also jog the memory! |
Viczig
Tinkerer
Username: Viczig
Post Number: 4
Registered: 12-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 23, 2009 - 04:45 pm: |
|
Glen was correct, the lens looks like its focusing to infinity with the distance scale reading 8 feet so the distance scale needs to be adjusted.
Anyone out there who can help with this?
Thanks,
Vic |
Glenn
Tinkerer
Username: Glenn
Post Number: 671
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 23, 2009 - 05:08 pm: |
|
Vic,
PM sent before I read this. Will dig out the info on location of focus ring retaining grubscrews later today. |
Glenn
Tinkerer
Username: Glenn
Post Number: 672
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 24, 2009 - 07:43 am: |
|
Vic,
Three radially placed grubscrews, situated between the actual scale engravings and the 'rubber' grip insert retain the focus ring on the focus mechanism. Just loosen to realign the ring and then gently retighten. Use a properly fitting, parallel ground screwdriver on the grubscrews, they are hardened out and a poorly fitting 'V' ground driver tip can break off one of the drive slot edges if one is hamfisted.
You should note that according to the manual, the design of the focus mechanism and optical carrier was change during the production run of this lens. Whilst you can exchange old and new focus units in their entirety, the individual parts that make up these assemblies are not interchangeable. If realigning the focus ring does not solve the problem, it could be that somebody has tried to repair the lens by just exchanging the odd part, instead of the complete assembly. Without the two units available for comparison the changes are non too clear on first examination. Just worth bearing in mind if you still have peoblems. |
|
