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Gez
Tinkerer
Username: Gez
Post Number: 67
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 17, 2009 - 06:04 am: | 
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I'm trying to remove some dirt immediately behind the first glass of the front cell. The front cell was easy to unscrew and is constructed on classical lines with metal retainers.
The front glass APPEARS to be held in place by the ribbed metal ring that acts as a light shield, however, trying to unscrew it using a rubber pad has no effect. So I'm wondering, is this shield meant to be unscrewed or is it glued in place?
Has a Forum member any familiarity with this lens? Incidentally, the general construction looks first class. |
Monopix
Tinkerer
Username: Monopix
Post Number: 18
Registered: 11-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 18, 2009 - 09:47 am: |
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Not sure if this is the same as the f/1.9 that I did recently but, if it is and by the 'ribbed metal ring' you mean the trim with the name and description on it, then it doesn't unscrew - the whole front surround comes off. Try setting the focus to the closest distance so that the front of the lens protrudes as far as possible, then grip the front of the lens and unscrew it. |
Lenskiller
Tinkerer
Username: Lenskiller
Post Number: 1
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 24, 2009 - 03:39 pm: |
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I want to clean the frontal lens of an Yashica ML 50/1,7 from fungus. I have mostly disassambled the lens and have the single housing of all lenses in my hand. I have screwed out the "YASHICA LENS" inscripted retainer ring and also screwed out the brass-retainer ring with black surface that holds the "helix housing" on the lens housing together. I did this with a small Hammer and screwdriver. But now I donīt know how to remove the last retainer ring, aluminium with black eloxal surface, that really holds the frontal lens in its housing.
Does anyone have an idea to do this without demolition of the retainer ring? |
Gez
Tinkerer
Username: Gez
Post Number: 75
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 24, 2009 - 04:06 pm: |
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Lenskiller, the front optical cell which contains 3 glass elements was fairly easy to unscrew as a complete unit. However, as far as I can tell there is nothing to be gained by unscrewing the collar holding the 3rd glass. The 2nd glass is held by a retaining ring that can only be accesssed once the 1st glass is removed. And the 1st glass is held by a ring which also functions as a light shield or mini-hood.
Is this what you refer to as the "black eloxal surface"??
If it is, then we are at the same problem area. |
Lenskiller
Tinkerer
Username: Lenskiller
Post Number: 2
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 27, 2009 - 05:32 am: |
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I wanted to unscrew the 1st glass, that has an exterior diameter of 41mm. I tried to solve the retainer ring beneath, exterior diameter 42.5mm,1.5mm thickness. That is what i discribed to have "black eloxal surface" on aluminium, but was not successful. I did this with a blade screwdriver and small hammer. I saw, i would destroy the ring without to solve it and stopped doing this. I had tried careful into both directions, left and right. Until now i have found only right-turn on this object. Now I am not shure, the 42.5 retainer ring has to be solved first. I have the same problem as you described. Maybe I have to grab the 2.5mm thick edge of 1st glas frame with brackets. |
Gez
Tinkerer
Username: Gez
Post Number: 76
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 27, 2009 - 11:33 am: |
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In my opinion the solution is to first unscrew the ring of 41mm exterior diameter. Over the weekend I made a spanner to attempt to unscrew this retaining ring, but so far I have been unsuccessful. It is possible that it has a left-hand thread but I suspect that the thread has a locking compound applied
Once the locking compound is loosened the front ring should unscrew easily. My advice is to try different tactics before resorting to brute force. |
Gez
Tinkerer
Username: Gez
Post Number: 79
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 05, 2009 - 12:06 pm: |
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Lenskiller: Success, I managed to unscrew the 41mm ring, it has a normal RH thread. The trick was to place a few drops of WD-40 penetrating oil in the gap between the 42.5mm and 41mm rings and let the oil soak in for a few days. It is not something I would normally do or recommend, but there was little to loose.
The first glass lifts off, no problem, exposing a retaining ring holding the second glass. The retaining ring on the back of the lens is also easy to unscrew releasing the third glass.
So if necessary you can remove the 3 elements for cleaning. |
