Canon nFD 35-105 f/3.5 aperture lever control rods

[Antti Takkunen]

Hi.. I removed the mount of the lens including aperture control rods to see if there would be an easy access to the rear elements for cleaning.

No luck with that but now I just can't get everything back together with aperture control working. I guess the main problem is the signal lever rod and the inner ring that connects to the aperture setting ring.

I can get the auto aperture lever working but the aperture closes everytime to the full f/22 position and doesn't stay as set on the ring. This is why I presume there is no (correct) connection between the aperture setting ring and the aperture unit.

Can send pics later if needed. Any advise would be helpful. Also interested to know is it a complicated project to clean the hazed lens element that is somewhere between the camera and aperture unit.

 

[flavio81]

Hi.. I removed the mount of the lens including aperture control rods to see if there would be an easy access to the rear elements for cleaning.

No luck with that but now I just can't get everything back together with aperture control working. I guess the main problem is the signal lever rod and the inner ring that connects to the aperture setting ring.

I can get the auto aperture lever working but the aperture closes everytime to the full f/22 position and doesn't stay as set on the ring. This is why I presume there is no (correct) connection between the aperture setting ring and the aperture unit.

Can send pics later if needed. Any advise would be helpful. Also interested to know is it a complicated project to clean the hazed lens element that is somewhere between the camera and aperture unit.

LOL you have exactly the same problem i have.

But the lens does separate "in half" near the place where the small ring that says "35-105mm" is placed. There are three (or four) screws there. I'm assuming, of course, that you have removed the rubber on both the focusing ring and the zooming ring, and that then you have taken away those two rings.

Keep dissasembling and you should see those lenses.

The only reason i couldn't fix my lens was that one of said screws has a broken head; i need to file it to be able to unscrew it.

 

[Antti Takkunen]

No rubbers on my lens.. Maybe you've got the other version that is f/3.5-5.6?

Today I took the lens to a service point that does old cameras and lenses.. They told me that probably there are some disks or rings around the aperture unit that have gone off from their correct position and possibly some spring missing. I may have caused this myself by trying to install the rods in wrong positions.. Of course they offered their help to disassemble everything and clean it. But it would turn out to be expensive compared to the price of the lens AND they could not guarantee that it would be 100% clean anyway.

I guess I don't loose much by trying to disassemble the lens but considering my skills my hopes are not flying high.. I hope to find some kind of service manual of the lens. No luck yet though..

 

[flavio81]

No rubbers on my lens.. Maybe you've got the other version that is f/3.5-5.6?

No, i am talking about the 35-105/3.5 fixed aperture Canon FD deluxe killer sharpness fantastic super duper zoom which back in the times showed how far advanced Canon was in the zoom technique, made specifically for pissing off Nikon. Also, corrected for chromatic abberrations specifically for taking pictures of the beautiful iceskapes of Finland so white ice correctly renders as white (and not as violet or green.)

Antti, fellow Canon FD shooter, the rubber striped ring that covers the zoom ring is removable. You can pry it off by putting a knife or something below it. NOW, for the repair you are attempting, i think it is not necessary to do. Or is it? Anyways, when you remove that rubber, you will see there are three or four tiny screws which couple the zooming ring with the inner zooming barrel. Removing them lets you remove the ring.

They told me that probably there are some disks or rings around the aperture unit that have gone off from their correct position and possibly some spring missing.

Seems they don't know about canon FD lenses.

You can do it, go dissasemble it yourself. It's not THAT complex. Just do not remove the two zooming groups (the ones who rock back and forth when you move the zooming ring.) They are not necessary to remove, for the repair you are attempting.

Now, how should you proceed with this lens? My suggestion is the following:

0. Place the lens facing down (lens mount up)
1. Remove the three tiny screws at the side of the lens mount, which hold the "chrome" part of the lens mount.
2. Remove chrome part from the lens mount
3. Remove the rotating part of the lens mount by simply pulling.
4. You will see that there are three or four relatively big screws, that hold the rest of the lens mount. Remove carefully holding the aperture ring in place.
5. Invert the lens while holding the aperture ring in place.
6. Remove the aperture ring by pulling it down. This makes sure the tiny lever spring that couples with the button next to the "A" setting on the aperture ring is held in place and will save you time.
7. You can place again the lens facing down if you want.
8. Now my memory fades here. If you see an obvious way to remove the ring that sits above the aperture ring and says "35-105" then remove it. Otherwise:
9. Remove rubber from zooming ring
10. Remove the three (or four?) tiny screws that couple the zooming ring with the inner zooming barrel.
11. Remove the zooming ring (pull it towards the lens mount side and slide it off)
12. Now at this point in time three or four chromed screws should be visible, remove them to be able to separate the assembly at precisely that joint.
13. At this point in time you should be able to see the levers from the lens mount side that should connect with the lens' aperture assembly levers. And you will be able to figure out how to make them work again.

TIP 1: Before attempting step 3, take a long look at how this part connects with the rest of the lens, so you have an easier time reassembling it later.

TIP 2: Go get a FD 50/1.8 (bayonet mount version) and disassemble it from the mount. The disassembly steps for the mount are almost identical, and the aperture assembly should be identical.

TIP 3: The aperture assembly on the lens (the assembly that actually holds the aperture blades) has a basically two levers:
lever A - lever that sets the aperture value (this is a lever that is part of a cam, let's call it "cam A")
lever B - lever that stops down / opens up the diaphragm.
Usually, on practically ALL "new FD" lenses, lever A can be moved (by the repairman) beyond its working range and then it will "locked" or "parked" on a value that is always minimum aperture (f22 or f32). To be able to "unlock" it, just take a look and you will see that there is a plastic pin that rides on "cam A". This pin is the pin that actually moves the diaphragm. It will be OBVIOUS that you need to raise this pin and move "lever A" so it unlocks.

TIP 4: Tip 3 was so obvious you can just ignore it, you'll figure it out by examining.

TIP 5: Another obvious tip. At one point in your steps you will find shim rings, they set the correct distance between the lens to the film plane, so don't forget to put them back when reassembling.

Universal tips :
1. Never force anything
2. Force it if you know how it should come out
3. Wash your hands before touching lens elements or getting close to lens elements
4. Make sure you know how the lens mount levers of a Canon FD lens work before
disassembling
5. Canon "new FD" (bayonet) lenses do not need lubrication, save perhaps for the rare cases in which the focus helicoid has "play".
6. Prevent screws from rolling and then falling down the floor by disassembling over a rag or cloth. This is very important, because finding tiny screws on the floor is the WORST part of lens repairing.
7. Lens elements are almost always held by a retaining ring that uses a spanner wrench.
8. When removing a lens element, take it off using masking tape. In this way you'll know which side of the element faces up.

 

[Antti Takkunen]

Wow.. Thanks sir!

You are absolutely correct, there is rubber. How didn't I ever notice that before..

I'll go deeper inside the lens during the weekend. And report back how it all went. Thanks again!

 

[flavio81]

Wow.. Thanks sir!

You are absolutely correct, there is rubber. How didn't I ever notice that before..

I'll go deeper inside the lens during the weekend. And report back how it all went. Thanks again!

Want an additional tip?

The two movable groups* (that slide inside the zooming barrel) "ride" on the zooming barrel by small rubber or plastic "doughnuts". Each zooming group is held by two or three screws, around each screw is the plastic doughnut, and this doughnut slides against the zooming cam (the zooming cams are the grooves machined into the zooming barrel). Over time these "doughnuts" decompose and what happens is that the zooming groups rattle or do not hold the correct position. How you can notice this? Because you focus the lens on, say, 100mm and then when changing to 50mm the focus point deviates too much.

I have successfuly replaced these doughnuts by using common 3M black electrician tape. Just wrap the tape around the screw until the correct thickness is achieved. Then the movable group can slide within the zoom barrel without play.

Of course, if your FD lens has no such problem, simply don't touch those zoom groups, otherwise by trying to disassemble, those plastic doughnuts might break.

Greetings from the far away country of Peru...

(*) Note: I can't recall if on this lens there is one movable group or if there are two.

 

[Antti Takkunen]

Many thanks for your helpful posts. And greetings from Finland. It is first hour of October 1st in here already.

I'm stuck at step 11 on your disassebly list. Can't get the zoom ring out because the Macro switch won't have room to come over.

Now I relate to the attached photo: On the far right there are 6 screws holding the probably aluminium barrel. Should I try to get that one away? Or is there any other way to find those screws holding the lens together (somewhere under the zoom ring)? These 6 screws on the right are very tight and made of soft material. Looks like I can't loosen them without causing damage to the screws.

 

[Antti Takkunen]

I can't really find a way to completely remove the zoom ring cover from the lens. Macro switch is just too thick to allow the ring to slide out from the rear end of the lense. I've tried to push and slide the macro switch inside too but with no luck and I'm not even sure if that would help. So, I really can't see under the zoom ring to find the screws you probably mentioned in your previous post. Maybe there is just something I can't figure out?

After some more searching I found this quote from mflenses.com forum. They are discussing about backfocusing the lense:

Just in front of the aperture ring is a black plastic ring with "35-105mm" in green letters, an orange line, and a serial number in white. It has three Phillips head screws with the heads painted black. Remove the three screws. The black plastic ring can now slide forward, revealing four more Phillips head screws. With the lens pointed downwards, loosen those four screws. They'll be tight, so push in with a lot of force so that you don't strip the heads while removing them. With those four screws loosened, the lens's mount and aperture ring are free to slide up and down. If you didn't have the lens pointed downward, the mount could slide off completely, leaving you to figure out how to slide it back on. So don't remove it. You just want to be able to slide it up and down a bit, and then re-tighten the screws when you have it in the right position.

Regarding the bolded quote the six (4 in some individual lenses?) screws I mentioned before are the way to bring out the aperture mechanism. I just wouldn't want to hassle with the back focus of the lens. And this text suggests that it might be difficult to get everything back again.

So am I right I've got two options:
1. Try to get rid of the zoom ring cover to reveal the screws you were talking about.
2. Try to open the six screws in the rear of the lens to slide out the rear lenses and the aperture mechanism.

I'm a bit worried to perform the latter option since the screws are very tight and seem to be made of some soft material. But if this is the way then I need to try..

Again, good advice needed.

 

[John Koehrer]

The screws i the silver ring appear to be in slots, not holes. That means they're
for adjusting focus.
Most zoom lenses I've worked on came apart from the front IE: the focusing
ring slid off the front

 

[flavio81]

Many thanks for your helpful posts. And greetings from Finland. It is first hour of October 1st in here already.

I'm stuck at step 11 on your disassebly list. Can't get the zoom ring out because the Macro switch won't have room to come over.

I did not find any problem to remove the "macro" switch. I think that if you rotate slowly the zoom ring, you will find a special position in which you can slide the macro switch out, if i recall correctly. Of course, for this you would need to remove the "35-105" plastic ring. But keep reading, please.

Now I relate to the attached photo: On the far right there are 6 screws holding the probably aluminium barrel. Should I try to get that one away? Or is there any other way to find those screws holding the lens together (somewhere under the zoom ring)?

Those 6 screws are the ones you need to access the aperture linkages. Congratulations! You found them!
So this means you don't need to remove the zoom ring for correcting the problem with the aperture linkages.

These 6 screws on the right are very tight and made of soft material. Looks like I can't loosen them without causing damage to the screws.

Yes you can. Just use the appropriate screwdriver. I don't recall if they are locked with glue, you can use a bit of naphta previous to removal.

The screws i the silver ring appear to be in slots, not holes. That means they're for adjusting focus.

Not really. Focus is adjusted by big (wide) shims (the diameter of the barrel inside).
The reason the screws are in slots is so they can be tightened down in place after putting the correct shim spacing. The screws alone are not responsible for adjusting focus, otherwise that joint (which is a critical joint) would be very fragile!!