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Disassembling Helios-40 85mm f1.5 lens
Posted By: Zivelot, 12-07-2012, 12:33 PM

I recently acquired a Russian Helios-40 85mm f1.5 lens (1st picture) with a stiff focusing ring. This is basically the same lens as Helios-40-2 but with an M39 screw mount instead of M42.
The glass is prestine and the aperture ring is smooth, but as I stated above it had a very stiff focusing mechanism. As a first thought I put some drops of Ronsonol into the mechanism inside which eased up the movement a great deal. Being a techy guy I decided to give it a proper clean that it deserves. Here are the steps if you want to do it on your Helios lens (should work with newer Helios-40-2 lenses as well as I gathered from the internet).

The first thing to know is that the lens is made up of two blocks: one holds all the lens elements together with the aperture mechanism while the other one is the lens mount and the focusing mechanism. They are simply attached by a thread. Disassembling the lens is fairly easy if it is not stuck too much. Just grab the outer part of the filter thread with one hand and the mount with the other and turn them anti-clockwise.
Once it has started to screw apart it is a fairly long way to go so be patient turning the two blocks around until they separate. When it is done place the optical block in a safe place as you will not need it until reassembly. (picture 2)

Once you have the optical block removed you can start disassembling the focusing mechanism. Remove the tripod mount that is held by two screws on my copy. (picture 3).

Locate the mini screws on the side of focusing ring. (picture 4) There are three of them. Loosen them up (or remove if you like so) until you can slip the ring off the whole block towards the mount. (picture 5) Now you should have a bare focusing ring removed. That is done.

We are getting closer. Again locate three mini screws on the black retaining ring and remove them (picture 6, step 1). When it is done start to unscrew the retaining ring in the given direction (picture 6, step 2) and slip it off the block when it comes loose (picture 6, step 3).

Now you can pull out the black rimmed focusing helicoids from the outer housing (picture 7). Locate the „leader screw” on the bottom and remove it. (picture 8). When you are assembling the lens the head of this screw slips into the grove inside the housing (picture 9).

Once this „leader screw” is removed you can screw the helicoids apart. Make sure to mark their relative position where they come apart. This is very important as otherwise you need to play around a lot to find the proper position to maintain infinity focus. I was lucky with my copy as the two stopping pins (infinity pins, picture 8) were exactly at the opposite sides (picture 10) at the starting point.

Now that every part is separated give them a good clean. As you will probably notice there is huge amount of grease applied by the Russian factory (I dare say they used grease not really intended for fine mechanics because mine was really thick and unrefined that would rather suit a tank or heavy machinery but not a lens). I used Ronsonol for cleaning. That does a great job.
For lubrication I found synthetic grease with silicon the best. Some might not agree but I have been using it for years and it is great.

Assembly is done in reversed order.

When assembling the lens make sure you tighten the black retaining ring (picture 6) so that it does not have any play but still easy to turn when focusing (don't forget to secure it with the mini screws). The infinity pins must touch each other as in picture 8 when putting back and fixing the focusing ring. The infinity mark on the focusing ring must be aligned to the central mark of depth of field scale. (picture 5).

Picture 11-15 shows where to put lubricant.

Now I can only hope this is all clear. My first language is not English but I tried my best with technical terms. Any comments or critique is welcomed and I am ready to update/revise this guide.

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