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Cableaddict
Tinkerer
Username: Cableaddict
Post Number: 1
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 30, 2009 - 11:22 am: | 
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Hey, folks. I sure hope someone knows the trick:
I have worked on quite a few lenses, but never before a Zeiss. I have all the right tools, and have never had this problem before. I'm trying to open the front of a ZEISS CZ Planar T* 85mm F1.4 (mm version)
The name ring is off, and the two retaining rings are easily accessible, but the bloody things won't budge. I have a really good grip with my spanner, and literally have put my entire strength into it. I tried clockwise and c-clockwise.
I tried the inner (cell) ring as well. - just as tight.
I tried heating it with a hair dryer (not too much, though)
In desperation, I even sprayed some Tri-Flow into the threads (I'm going to clean it, anyway) but it's as if those rings are epoxied in.
Is there some special trick with this lens?
Any ideas at all? |
Ethostech
Tinkerer
Username: Ethostech
Post Number: 137
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 02, 2009 - 05:21 am: |
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This is not a definitive answer because I don't know that particular lens - but I have been such route on various lenses from time to time and the following are possibilities:
a) The stubborn ring may be held by three or four headless setscrews (in Australia we call then "grubscrews) which may be under the rubber grip of the focusing ring. This is the most common reason for rings which just won't budge.
You MUST eliminate this possibility before moving to (b) below -otherwise you will surely do some damage,
b ) The immoveable rings "may"have been locked with varnish.
You might pick up a few small drops of acetone on the end of a mini-screwdriver and feed such around the thread-line. Leave overnight and then repeat. Then give it as much muscle as you deem prudent. |
Cableaddict
Tinkerer
Username: Cableaddict
Post Number: 2
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 02, 2009 - 11:00 pm: |
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Thanks, Ethostech.
I have tried acetone already, but only let it sit for maybe 5 minutes. It was suggested that it would just evaporate after that, and let whatever was in the threads re-harden. Is this not so?
Also, is there anything inside a lens that acetone can damage? (plastic, maybe?) This really worries me.
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I wil check for hidden set-screws tomorrow. That's an interesting possibility. I'll report back here.
THANKS! |
Cableaddict
Tinkerer
Username: Cableaddict
Post Number: 3
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 02, 2009 - 11:21 pm: |
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OK, I went and got the lens, I couldn't wait to check.
Re the set-screws: That's an interesting possibility, and good to know for future lenses. I don't think in this case:
I have the rubber off, and there are six set-screws, but they are set way back, near the aperture mechanism. They are nowhere near the retaining rings. Therefore, I think they are most likely for adjusting the infinity-stop.
I don't want to loosen these & mess that up.
BTW: There is a white "4.9" handwritten in this area, likely by the original tech. I assume it's some kind of adjustment measurement. Any idea what it means? |
Ethostech
Tinkerer
Username: Ethostech
Post Number: 140
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 04, 2009 - 06:55 am: |
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If I had the lens before me I would know abput those mentioned set-screws. Three of them may be to release the entire focusing ring so it comes off complete with the front element module. But I am not advocating any such experiment. better to watch this subject post. Someone will have definitive experience of the particular lens.
You are right about acetone and plastics - but I have never seen any plastic parts in Zeiss lenses of the Planar quality.
And yes again - the acetone evaporates quickly but once softened the varnish does not return to any former rock solid state - at least for a few years. |
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