Helios 44M Aperture A/M Repair
This is a photo blog post on how to fix the A/M or Auto/Manual diaphragm switch on a Helios-44M M42 mount camera lens.
Keep reading for a photo guide on dis-assembly and re-assembly.
This is going to be a quick guide on how I fixed the Auto/Manual switch on both of my 44M lenses. They were purchased from EBAY with non-functioning automatic diaphragms, but they were both easy to fix. Keep reading for a visual guide. Also, if you are interested I have a guide on adjusting and cleaning the focus on Helios 44M lenses here.
What you need:
- Ronsonol – lighter fluid in a yellow bottle designed for removing grease and tar. I got mine at Wal-Mart, but you apparently need to be 18 to buy it).
- Q-tip (s) – for applying the Ronsonol to the aperture blades
- Micro Fiber Cloth – for removing Ronsonol, grease, tar, and other bits of grime from the blades. These also work great for cleaning lens elements due to how well they pickup dust. I usually buy them in a large pack in the Wal-Mart automotive section. They’re designed for cleaning cars, but are the same as more expensive ‘lens cleaning cloths’.
- Small Screwdriver – flat blade from an eyeglass kit or electronics repair kit. You’ll need this to remove the rear screws from the lens.
As you can see above I have two different 44M lenses. According to this link the lens to the left was manufactured in the Valdai Optical-Mechanical Factory and the lens to the right was made by Krasnogorskiy Mechanicheskiy Zavod (KMZ). Oddly enough, the Valdai seems to be of a heavier build and has a metal ring hooked into the aperture ring instead of plastic like on the KMZ model.
The first step is to remove the three screws holding the back onto the lens. Don’t remove the fourth screw that holds the A/M switch in.
Gently pull the back off of the lens to expose the rear element. At this point be VERY careful not to lift up the aperture ring. It has two tiny ball bearings that make it ‘click’ as you rotate it and it’s a pain to get them both back in.
I would also like to show you the rear of the Valdai lens. Notice the ring that hooks into the aperture selector is metal instead of plastic like the KMZ above.
At this point you should be able to grip the rear portion of the lens assembly and gently unscrew it. I didn’t have to use any force on either of my 44M’s to take this part out. Just to clarify I’m talking about removing the rear element and its inner element in one piece. If you happen to notice debris trapped between the two you can unscrew the inner from the outer and clean them. Just be CERTAIN you get the rearmost element back in the same direction you took it out.
This is what we’re going to use to break up and remove all that cold war era junk from the aperture blades. I put some on a q-tip and touched it on a rag to wick some of the excess liquid off. After that I touched it all over the aperture blades (after manually closing them as close to F16 as they would go). I would them open/shut them manually to work the fluid in. Be sure not to scrape the q-tip along the blades or press too hard. Scraping it along will catch fibers in the blades. Gently dabbing will still deposit plenty of cleaning fluid without worrying about it hitting the glass element below.
After applying fluid and manually operating the blades to work it in I took a Micro Fiber Cloth like the one above and gently wiped the blades. It seemed to work best when they were closer to F16, due to more blade being exposed. Don’t press too hard or you could damage the blades. You just want enough pressure to get the gunk off. You may even need to repeat the process a few times, but you should see black grunge coming off onto the cloth.
When you are satisfied that you cleaned the blades, or want to give it a try stick the rear portion of the lens back on. You’ll need to watch where the catch on the A/M switch is to make sure it hooks onto the aperture arm. You should also be able to trigger it with the A/M switch before putting the three screws back in. If the blades still hang you may need to clean it a bit more. If it works put the three rear screws back in like you took them out and it should be good.
You can see the blades on my lens here from the front. It closes much tighter than when I purchased it and much smoother to boot. Playing with the aperture ring before cleaning it I think the lowest F-stop I could get was about F5.6.
This next part is optional or possibly required if you knocked the bearings out of the aperture ring.
*OPTIONAL*
When you rotate the aperture ring it locks via the help of two tiny metal bearings. Getting them both back in is a pain, as you have to fit them into a little recess and slip the ring back over. I actually found out I like the ring better with only one bearing. It’s easier to adjust and seems to make less noise. In order to use one bearing place one of the bearings into the hole as shown above. Then line up the aperture ring with the bearing and slide it down onto the lens. You’ll need to keep it off the bearing until it bottoms out on the lens and then push it inward toward the bearing, otherwise you’ll most likely knock the bearing out.
Posted by falcoln0014 
November 2009
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