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Message |
    
C70man
Tinkerer
Username: C70man
Post Number: 1
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 29, 2009 - 02:58 pm: | 
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I received this older used lens in the mail and the outer lens element moves. If I place my finger on it, it will steady...so how can I keep it from moving? It has a canon fd mount and will not focus to infinity, but the lens is very sharp up to 100' or so. Even with the outer loose lens.
Any way to open up the lens and fix it? Any ideas would be greatly appreciated. |
Tom_cheshire
Tinkerer
Username: Tom_cheshire
Post Number: 32
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 29, 2009 - 05:00 pm: |
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Tighten the retaining ring that holds it in there. If that ring is frozen or jammed then sit the lens on its butt pointing straight up and put a dab of glue on three edge corners to keep the element locked in place. Good glues: contact ement or instant. A little dab will. |
C70man
Tinkerer
Username: C70man
Post Number: 2
Registered: 05-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 29, 2009 - 05:26 pm: |
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I don't know where the retaining ring is... the lens has a lens shade that moves up and down on the lens so I can't see any ring. If I grab the outer portion of the lens, can I turn it with pliers or something to get it loose? |
Mndean
Tinkerer
Username: Mndean
Post Number: 149
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 29, 2009 - 11:13 pm: |
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The retaining ring is often the ID ring that has the brand and focal length/aperture information. If it's on there tight, then I don't know what could be causing the looseness except if there's another ring underneath that one to hold the element. Depends on the manufacturer how they're put together. My Minolta Celtic MC 135/2.8 front element came off as soon as the ID ring was unscrewed. |
Glenn
Tinkerer
Username: Glenn
Post Number: 597
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 30, 2009 - 05:45 pm: |
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The loose element and the lack of infinity focus suggest that this lens has been 'got at'. I doubt that just jamming the front element solid will solve your problem, you should carefully strip it down and check the optical assembly and focus helical.
I have no idea what this lens looks like, so cannot offer specific help. You should first examine the focus ring and scale, do the min and max focus distances align with the datum? If they don't, this is a good indication that lens could be wrongly assembled. If focus ring and scale are in alignment, then it is possible that somebody has removed the front elements to clean them and not screwed then in correctly. In this instance I would try and remove the front optical cells and look at how the elements sit in their retaining rings. Could be that a simple re-assembly of the front of the lens is all that is required.
Do not attempt to take the focus helical apart without marking suitable reference point to aid re-assembly, these units use multi-start threads, so putting them back in correct alignment can be a long winded and frustrating affair! |
