REPAIR Canon FD 1.4/50mm SSC

[stevemark]

A few days ago the local photo store gave me a really nice looking Canon FD 1.4/50mm SSC (like new indeed) for repair: Everything was looking good, except that the aperture was stuck wide open. I did expect an easy cleanup of the aperture itself, but boy was I wrong!

Removing the frontring (nameplate) should have been easy and straightforward: Take one of these rubber tools and rotate it counterclock wise. Yet the ring simply didn't want come off. A few drops of acteone didn't help either. Looking very closly at the front ring I finally could see that one side was precisely aligned with the lens surface, while on the other side there was a tiny gap (maybe 0.3mm or so). I figured out that the ring was slightly tilted and therefore jammed into the thread - thus unscrewing was nearly impossible. Since the ring is made of plastics, I was able to push it back into its correct position, and to finally take it off:



Now there are three screws holding the foremost part of the lens in place - remove them, and remove the front ring (not shown here):



Next - again with three screws - comes the removal of the focusing ring:



Then there's stopper for the focusing mechanism ("infinity" and "MFD") - remove it:



Measure the correct distances:


Now the entire lens block can be taken out - mark the position where it comes apart. And look at the beautiful SN of thei lens!


Extract the lens block:


Remove the silver (alu) ring with its focusing threads:


NEXT STEP: DISMANTLING AND CLEANING THE APERTURE MECHANISM

[stevemark]

PART II - DISMANTLING AND CLEANING THE APERTURE MECHANISM


Now that we have access to the lens block & aperture mechanism itself, we can close the aperture manually. There's lots of oil on the blades - which seems a bit strange given the fact that I haven't seen any separation of the grease, let alone oil on the outer surfaces of the lens block ...



OK - let's move into the optical block itself:



Front group removed:



And here comes the aperture mechanism itself - COMPLETELY COVERED WITH OIL, I even would say "swimming in oil". WTF ?!?



Before starting to work on the aperture mechanism (which is a nice separate piece - well done!) we can take out the rear lens group as well:



Now the aperture mechanism - extract these three screws:



... and remove the cover:



The base plate of the aperture mechanism after removing the aperture blades: Everything is full of oil!!



Looking at all this mess I decided to get an additional can of acetone at the hardware shop ... just in case . Cleaning all those parts carefully did require quite a lot of time indeed - aperture blades, aperture mechanism, focusing threads, etc.

When all parts were done I started reassembling - here are the aperture blades, put in their correct position again:



Aperture mechanism closed and fully functional again - snappy and dry as it should be:



Looking at the incorrectly sqeezed in front ring / nameplate, and the oily mess inside the aperture mechanism, I strongly suspect that someone must have opened the lens recently, trying to "repair" the aperture mechanism by applying lots of oil. Nice try, but didn't really work out, and so the lens ended up here at my desk ...

[stevemark]

PART III - REASSEMBLING THE FOCUSING THREADS

Canon FD/nFD lenses have a mixed reputation when it comes to servicing, partly because of their somehow complicated focusing and aperture mechanisms.

I'll try to explain carefully how to re-assemble the FD 1.4/50 SSC.


Here's the inner part of the focusing mechanism (carefully cleaned, but not re-lubed yet) as well as the aperture mechanism (carefully cleaned as well - DO NOT APPLY OIL HERE ...):


Aperture mechanism re-inserted into the inner part of the focusing mechanism:



Rear lens block re-insered as well (BEWARE: later on I had to remove it again ... so you can skip this step for time being):



Front group inserted again:



"Middle ring" of the focusing mechanism added (after re-lubrication with Losimol 33B grease, of course):



Now the tricky part: Adding the third (outer) part of the focusing mechanism. As you can see I had to remove the rear optical block again, to have access to the three (!) internal coupling mechanism of the aperture mechanism. Yeah, the FD mount is kind of overengineered indeed ... OK - first this connection has to be engaged:


Then this one:



And finally this one:



Do it carefully, take your time, and do not rush. It's a matter of two or three minutes at most if done properly.
Here the re-assembled lens - only the focusing ring and the front fring are still missing ... everything else is in its place and working properly!



(IMAGE OF THE SERVICED LENS WILL FOLLOW TOMORROW)

Well, that was more work than anticipated - since I had to remove all that oil, I decided to clean and re-lube the focusing mechanism as well. Interestingly, the focusing mechanism has a "double thread" usually found only in expensive primes such as the 1.2/55 SSC, or the 2/135 and 2.8/200 lenses.

S

[lumens pixel]

Great work. Thank you for sharing.

[BrianSVP]

The mount is a bit tricky/unintuitive to disassemble/reassemble, but doing so makes reassembling the helical much, much easier, and it decreases the risk of bending the internal aperture linkages.

It also gives you the opportunity to clean/regrease the thread on the breech ring, which is something of a grit magnet.

I have one of these lenses coming in in a few days and can add pics of the procedure if you are interested.

[stevemark]

The cleaned and re-lubed sample on the left, along with anpther sample that still needs cleaning (right):



S

[stevemark]

[BrianSVP]

OK, here are some photos I took on how to do the mount disassembly/reassembly. This is the "Green O" version, but the interior mechanics are all identical.

The first thing to do is to take the mount screws out. To get to them, you'll have to turn the silver breech ring counter clockwise. There is a lock mechanism on this ring that can be disengaged by pressing the silver spring indicated by the arrow with a flat head screwdriver.



This is what the screws look like.



You can then pull the entire mount off. Keep the rear of the lens barrel facing upwards, since there are some little bits that can fall off.

Now, in order to disassemble the breech ring, we need to take the aperture arming linkage out, which is indicated by the arrow. Take note of its position between the two levers and the direction it is facing.



We need to remove the two small JIS countersunk screws on the side



Now, the linkage drops out.



At this point, you can remove the breech ring by turning it clockwise (reverse threaded).

The thread tends to get very dirty, so you can clean it out and regrease it. The knurling on the silver ring tends to collect dirt as well, so with it off the lens, you can wet clean it.

I don't recommend disassembling the inner portion of the mount, as there are about 100 ball bearings in there, and it is NOT easy to disassemble/reassemble. If it is really bad, you could immerse it in solvent or wet clean it in an ultrasonic cleaner and blow it out to remove any lingering water.



To remove the aperture ring, first we have to remove the auto aperture signalling pin mechanism. The pin itself is circled and lifts out. It has a very small spring on it that's easy to lose, so be careful. There is a stainless steel ramp piece below it that is attached by two screws. Remove them, and the ramp piece slides out the side.



Here is the mechanism disassembled.



Now the aperture ring lifts off.



The Auto lock button remains attached.



This shows the spring mechanism from the lock button. If you need to disassemble this because the button is gunked up, it can be done by removing the two small black screws on the side of the ring.



The lens has two ball detents, one for whole stops, and one for half. This makes it a bit trickier to reassemble than lenses with a single detent.



Here are the ball detents and one of the springs



OK, now, assuming we have disassembled the front down past the outer focus ring, following Steve's instructions, we can now disassemble the helical.

The screws for the synchronizing key are indicated below with the arrows. Also note the cam that controls the aperture. There is a small spring-loaded following lever at the bottom. If the cam is pushed too far past the lever, it will get stuck in the wrong position, and you will have to to reach back in and reposition it with tweezers or similar upon reassembly.



Remove the key screws:



Now we are going to turn the front half of the helical out. I've put marks at the entry/exit points corresponding with the edges of the notch on the middle helical ring.



The key remains in the keyway as it comes out.



You can pull it out for cleaning/regreasing.



Ok, now we can remove the center helical ring from the outer helical ring. There is a small metal strip on the side of the ring with three set screws that sets the infinity and minimum stops. Steve covers this above. Mark its position, and remove it. Then you can turn the middle ring out by turning counter clockwise.

Note that unlike on many other lenses, this ring has multiple entry points, so inscribe a point at where the ring leaves the outer helical.



Clean the helicals and regrease them, as well as the keyway, and put the key back in for reassembly.



Once you've done the cleaning indicated in Steve's tutorial, as well as cleaned the components you've accessed in the mount disassembly, reassemble in the reverse order.

Now the magic of how to reassemble. This will make it MUCH easier than trying to do it yourself, because if you don't know these, it can be infuriatingly difficult.

When you reassemble the aperture ring, the two ball detents can be very difficult to get back under the ring. The easiest position at which to do this is f/16.



Second trick: after you have put the auto pin ramp back together, turn the aperture ring to auto for the rest of reassembly. This will extend the pin upward, allowing you to align it with its corresponding hole on the mount.



Third trick:

Before reattaching the mount, put the actuation lever in its locked/manual position. From the inside of the ring, you can see the leaf spring lock that holds the lever in place.



OK, let's look at this pic again. look at the cam position:



On the other side of the cam, you see this fork-like projection. It is fragile and is the part that can get bent/damaged if you use Steve's reassembly method. It should be positioned to the right of the projection on the aperture ring.



OK, now you want to align the corresponding lever on the mount with it and drop the mount down.




Now jiggle the mount until the auto pin falls into its little hole. At this point, all the screw holes should be aligned, and you can put the screws in. Check that the aperture works (remember to unlock the lever in the back and the trick with the leaf spring under the ring to allow the aperture to be put into armed position). If everything works, you are done!

[BrianSVP]

I think I've worked on that L lens exactly one time, and it was several years ago. I'll check if I still have some notes somewhere. Otherwise, if you can send some pics, I might be able to help figure something out.

[sasquatch]

Great guide, extremely thorough. Thanks for sharing!
I wish I had had it when I got one in April with a stuck aperture.

As it was, I was able to clean the aperture in situ by removing the front optical block then the mount/ rear optical block but with this guide could have done a 'proper' job. My repair is still going strong but I don't think it was flooded with oil like yours.

Now bookmarked for the day my botch job eventually comes undone...