This Canon Serenar 85mm f/2.0 is in excellent condition, but has a bit too much drag on the focus ring and some oil on the aperture blades. I know with a CLA it will operate smoothly and more freely.
For an 85mm lens it is long, but has a small diameter. It’s also very heavy, being made almost entirely of brass. There are no plastic parts on this lens.
There are a lot of little screws to keep track of. The set-screws come in groups that aren’t necessarily the same size. Still, compared to other lenses this one is pretty simple.
You can read more about its history in another post.
These two screws don’t need to be removed. I removed them without knowing.
With the set-screws removed the mount section separates from body.
Remove this screw.
The brass sleeve separates from the mount section.
The mount section can be removed now.
The depth-of-field ring can be removed.
Remove these set-screws from around the focus ring.
This shows where the distance scale aligns with the focus grip. Note the larger stop screws to the right and the line on the brass helicoid barrel. This information will help in reassembly. Remove the distance scale.
Remove these set screws from around the focus ring.
Use the scribed lines on the helicoid to establish a reference for where the focus ring lines up. This information will help in reassembly.
There are some more hand-scribed marks further down the helicoid.
The focus ring can slide off now.
With the helicoid all the way to one end of its travel, look for another reference mark for where it meets the front lens section. This information will help in reassembly.
With the helicoid unscrewed we can see the old grease. It’s not terrible for a lens that is 65 years old. It definitely needs replacing to make the lens operate smoothly.
Using a toothbrush dipped in acetone I brush away the grease from the threads.
The helicoid is clean.
The loose part of the helicoid can be dipped in acetone. An ultrasonic cleaner would work well, too, but I didn’t own one at the time.
Remove another group of set screws from around the aperture ring.
Once again, find a reference mark for aligning the aperture ring.
Removing the aperture ring reveals the aperture stop screw.
Remove these screws to free up the helicoid section.
Find another reference for where the helicoid section lines up with the front lens section. This information will help in reassembly.
Unscrew the helicoid section.
Turning this lens section by hand will unscrew it.
The lens section is removed, revealing the aperture blades.
The aperture blades have some oil on them. There are 15 blades on this lens, which is an impressive number.
The 15 blade aperture creates a very round circle.
The oil on the aperture blades really shows here.
Remove the set-screws from around the front bezel.
With the set-screws removed I need a bit of grip to unscrew the bezel. A rubber band works well here.
The front bezel unscrews.
The aperture section is separated from the front lens section.
Another good look at the oil on the aperture blades.
This aperture pin connects the brass aperture armature ring to the aperture housing.
The aperture pin is removed.
This is the aperture stop screw. It produces the hard stops at each end of the aperture ring’s travel.
The aperture stop screw is removed.
Slide the brass aperture armature ring off.
Remove some more set-screws.
The spanner ring holds the aperture housing in place.
Use a spanner tool to remove the spanner ring.
With the spanner ring removed the aperture housing opens up.
Looking at the aperture blades retracted, notice how the small nubs are not centered on the blades. They sit towards the outside of the aperture housing.
The aperture blade retaining ring is removed.
The only thing left to do is clean the blades and put them back together. Notice that the pin at the bottom which sits in the aperture retaining ring is centered on the blade. The pins at the top are offset.
The aperture blades have been cleaned and put back together, which is difficult to do even with larger blades like these.
Like I said, there are a lot of little screws, but overall this isn’t a very hard lens to work on. Just be careful because they are very old lenses and slightly rare.
If you liked this CLA be sure to read the other CLA articles I have. There are three of these Serenar lenses and a Canon FD 35mm tilt/shift.
Your photos were very helpful in overhaulling my Serenar 100/4! The hardest part was reinstalling the little curved L-shaped brass piece under the focus ring. Thank you for this tutorial.
Hello, I just acquired a nice minty looking Canon (IV F or S) rangefinder with three lenses. The 50mm and 35mm Serenars are fine I think, but the 85mm f1.9 I has 1 or 2 aperture blades that have left their place and bent. I unfortunately worked the aperture before I noticed this, not sure if I made them worse. They might be fixable if someone could reach them from the front. I have been able to get to them from the back, but that’s not enough. I’m afraid to disassemble the entire lens. The glass looks great and I would love to save this. Is there somebody who I could send it to for $$ to try and save it?
I can certainly understand the need to send it out when something is damaged. I don’t know anyone in particular, but there are places like Duclos that might work on it. I saw someone mention a camera repair company in North Dakota which I think is called Camera Clinic. Good luck!
Well, as it turns out after sleeping on the problem, I used a curved dental-style metal pick and carefully went in through back of the aperture opening to the front of the blades and easily popped it back into place. We’ll see how it works!
Great info and good pictures Thanks for putting this together. I have Canon Serenar 85 f2 #55400, pretty close to yours. After taking that first set of set screws off, I cannot budge the mount section from the body at all. I tried removing the two screws that you said do not need to be removed, but that did not help. Seems like it is all one piece of metal here. Any ideas for how to get this apart?
Mark O'Russa 
Your photos were very helpful in overhaulling my Serenar 100/4! The hardest part was reinstalling the little curved L-shaped brass piece under the focus ring. Thank you for this tutorial.
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Thanks for the post – it was a tremendous help for cleaning my canon 85mm f1.9!
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Hello, I just acquired a nice minty looking Canon (IV F or S) rangefinder with three lenses. The 50mm and 35mm Serenars are fine I think, but the 85mm f1.9 I has 1 or 2 aperture blades that have left their place and bent. I unfortunately worked the aperture before I noticed this, not sure if I made them worse. They might be fixable if someone could reach them from the front. I have been able to get to them from the back, but that’s not enough. I’m afraid to disassemble the entire lens. The glass looks great and I would love to save this. Is there somebody who I could send it to for $$ to try and save it?
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I can certainly understand the need to send it out when something is damaged. I don’t know anyone in particular, but there are places like Duclos that might work on it. I saw someone mention a camera repair company in North Dakota which I think is called Camera Clinic. Good luck!
LikeLike
Well, as it turns out after sleeping on the problem, I used a curved dental-style metal pick and carefully went in through back of the aperture opening to the front of the blades and easily popped it back into place. We’ll see how it works!
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Great info and good pictures Thanks for putting this together. I have Canon Serenar 85 f2 #55400, pretty close to yours. After taking that first set of set screws off, I cannot budge the mount section from the body at all. I tried removing the two screws that you said do not need to be removed, but that did not help. Seems like it is all one piece of metal here. Any ideas for how to get this apart?
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