carstenw
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 p.4 #5 · lens repair, modification and disassembly guide thread | |
Well, today was a very happy day for me: I was able to open and clean not one, but two lenses which I have bought for very nice prices, but which had "fog" inside.
The first was an XPan 90mm lens I bought many months ago, and since I had never attempted anything like this, I was reluctant to risk a few hundred Euro on a botched job.
The saviour came in the form of an RZ67 Sekor Z 127mm lens which I just picked up for almost nothing, and which had the same problem. It appeared to have some fog somewhere inside near the rear of the lens, so naturally I looked at the rear first, and found a notched ring, which I was able to remove with a normal spanner, something like this:
http://www.micro-tools.de/en/Spanner-Wrenches-oxid/Spanner-Wrench-Economy-Slotted.html
However, after that nothing went anywhere, so I put it on again and started looking from the front. There was also a notched ring, but trying the spanner on it only made clear that it bumped against something in front of it. I looked at it unknowingly for a while, and eventually realised that the whole front plate was one piece screwed into the body, and I was then able to remove that plate with a rubber stopper, something like this:
http://www.micro-tools.de/en/Lens-Tools-oxid-1/Lens-Ring-Tool-Kit.html
After that, trying the spanner again got me not the inner ring loose, which is was meant to, but a whole assembly of the front few elements, probably up to the aperture or shutter. A quick look with an LED flashlight showed that there was a problem, which looked like it might be on the rear element. Cleaning it proved this right. Then I looked at the front element of the remaining group in the body, and it was also dirty. Cleaning that was a bit tricky, being still in the body, but I managed, and after putting everything back together carefully, the lens is now nearly as clean as when it left the factory! Yay!
This gave me the guts to try the 90mm XPan lens again. This time, the fog was very fine-grained and dense, and looked to be on the inside of the rear element, so I tried the first ring with the spanner, which came out readily. The lens wouldn't come out though, so I proceeded to remove the next thing as well, which was the whole rear group. After getting this out, I was able to get the lens out with a couple of taps. Cleaning it on the inside and the rear surface of the lens in front of it cured it as well. Putting it back together was made slightly more complicated by the fact that when the lens hopped out, it turned a couple of times so I wasn't sure which way was right, but luckily one side was very concave and the other slightly convex, and I do recall that the outer surface was convex, so it went back together again after all.
Now I have two great new lenses to try out, and one less todo item on my list 
Photos supplied on request.
If I ever need to do something like this again, I will buy another couple of high-quality spanners, and a couple of different sizes of suction cups. This should make it easier to open things and remove elements.
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