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Message |
    
Casual_collector
Tinkerer
Username: Casual_collector
Post Number: 9
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 18, 2009 - 12:48 pm: | 
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I have an old, bayonet mount Yashinon stripped down just for fun. I'm going to clean and lube the helical. This lens is a double whammy unit with multiple start threads on both sides of the helicoid. Does anyone have a foolproof or at least logical method of getting it back together right? There's four threads on each side of the helical so I figure there's at least 15 ways to do it wrong. Thanks.
Bill |
Glenn
Tinkerer
Username: Glenn
Post Number: 616
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 18, 2009 - 05:13 pm: |
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The simplest method is to scribe reference/datum lines across various areas before starting to unscrew - on some lenses setting the focus ring to either max or min focus, before removing the inner barrel, is important.
If you are experienced, it is possible to just gently unscrew until the point of separation is found - you then mark both parts with a reference line before finally fully separating the two pieces.
On many lenses it is possible to make use of the depth of field and focus scale engravings as reference points, anything that lets you align the components correctly on reassembly will do. |
Casual_collector
Tinkerer
Username: Casual_collector
Post Number: 11
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 20, 2009 - 07:37 am: |
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The lens is back together. I did find some scribed marks, perhaps benchmarks by the original assembler. I screwed the core into the helical til it looked right (Three chances to get it wrong) Then screwed that into the main body (3 more opportunities to get it wrong). It still took many attempts as the aperture setting fork is on a threaded ring that must be positioned just right so a travel limit screw doesn't bind in its slot.
Nicely made lens, BTW. Brass and aluminum helicoid and the diaphragm actuator runs on dozens of ball bearings.
Unable to check infinity focus as the body is jammed and the mirror broken. I also want to take it apart and do it again with lighter grease on the helical and some laquer on the screws. |
