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August
Tinkerer
Username: August
Post Number: 3
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 11, 2008 - 02:50 pm: | 
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I have two Zeiss-Ikon Nettar folders both of whose middle (or alternatively rear) lens elements need to come out for cleaning. Both are locked in by evil-looking snap rings sitting right next to the lens glass and embedded rather deeply in their grooves. Even with micro snap ring pliers it is very difficult for me to imagine how those are going to come out without damaging the glass. Anyone got any tips for removing these safely?
August |
Dgillette4
Tinkerer
Username: Dgillette4
Post Number: 223
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 11, 2008 - 03:42 pm: |
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If they have holes in them the pliers or draftsman deviders. I have done some with a thin blade or pin behind the ring center. But as you say be careful. Don |
Dgillette4
Tinkerer
Username: Dgillette4
Post Number: 224
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 11, 2008 - 03:48 pm: |
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Maybe Rick Oleson has an idea if he sees this post..Don |
August
Tinkerer
Username: August
Post Number: 6
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 11, 2008 - 06:11 pm: |
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Thanks. These are not the type of ring that unscrews. They have to be pried out. I think a micro screwdriver inserted under one end and gently forcing it up and away from the thread must be the way to go. It probably makes sense to start by sticking a piece of removable painter's masking tape over the glass to protect it. |
Glenn
Tinkerer
Username: Glenn
Post Number: 371
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 11, 2008 - 06:53 pm: |
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You are quite correct with the choice of a micro screwdriver as the tool. However, the choice of masking tape as a method of protection is unwise. Use a piece of old negative - cut the end to the radius of the ring - and hold it in place with a small piece of double sided tape if you want.
You may find that if you use a flat wooden tooth pick, to stop the ring snapping back into the grove, the removal becomes less of a problem. Use one end of the ring as the fulcrum point, to lift the other end out of the groove. Place the tooth pick into the gap and the reposition the screwdriver to lift the ring out of the grove. Do not allow the end of the ring that is still in the groove, to flick out over the lens surface. The ends can be quite sharp, and are even capable of cutting through the film stock used as protection.
I always round off the ends using a fine diamond file or suitable stone - cuts down the risk of damage on reassembly etc. |
August
Tinkerer
Username: August
Post Number: 7
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 11, 2008 - 09:12 pm: |
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Thanks Glenn. I just tried your method and learned why they are called snap rings. After retrieving it from behind the desk, I am now rounding the ends. I can see that eye protection is a good idea during this operation.
Now I'm a little stumped though. I guess I expected the lens element to pop right out when the ring was removed, but it didn't. I'm trying to figure out the safest way to pop it out of there. |
August
Tinkerer
Username: August
Post Number: 10
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 12, 2008 - 11:41 am: |
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Just to follow up, this little adventure ended happily. The glass was gently pried out and cleaned, put back together (with slightly less snap in the snap ring in case I have to do this again) and one more classic is now returned to the ranks of the functional.
In the course of all of this, I came across telltale scrapes and scratches which indicated that someone else had tried to do this previously, but given up. That always makes me feel like Indiana Jones stumbling over the skull of a previous adventurer.
Anyway thanks Don and Glenn for the tips.
August |
Glenn
Tinkerer
Username: Glenn
Post Number: 374
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 12, 2008 - 03:28 pm: |
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Ah yes, eye protection - Sorry! I tend to forget about this as I need to wear glasses all the time. From the onset of my shooting days, I have always specified shatter proof lenses. Judging by the dings that various pairs have picked up over the years, my glasses have stopped quite a few sore eyes - maybe even worse. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 594
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 12, 2008 - 08:18 pm: |
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To lift out a snug element, I have a little stick with suction cups on both ends - I think it was made for grinding valves - which sort of works sometimes. Micro tools has a better one, a squeeze bulb with a suction cup around the opening at the end... that should grab the element pretty well without marking it. |
August
Tinkerer
Username: August
Post Number: 11
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 12, 2008 - 08:22 pm: |
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Another snap ring gave me a lesson tonight. This time I tried to take out rear snap ring holding in the back element in a Nettar 515/2. This one is bigger, stiffer, and nastier than the ones that hold in the middle element. So much so that the glass couldn't take the strain when it started to flex. So much for one 10.5cm f6.3 Novar. And even with the lens broken, the ring still won't come out.
Well, no big deal. The fungus which was why I was trying to remove this element had probably scarred the lens anyway, and the front element and Derval shutter are salvageable, for what they are worth (which is not a lot!). I had been thinking of souping up this body and bellows, which are in good shape, with a better lens/shutter combo and now am free to do that. Still, wrecking optics is no fun, especially since I can't figure out what I could have done differently to prevent it -- other than limit myself to removing the smaller snap ring in future cameras. |
