Assemble Canon FD 50mm F1.8 SC lens!

I was trying to fix the aperture cause it was sticky but now, I'm not able to assemble all at one piece. It seems to be a simple work that I need to screw two pieces at once at a specific degree but I can't put them together.

I tried to find a manual assemble this but I couldnt find anything since nobody ever disassembles every part. I really dont wanna send this to a repair shop because they want me to charge $100 for a simple job. I just need to find a way to rotate.

Any information about assembling Canon FD 50mm F1.8 SC??

What is the serial number of the lens?

315708

There's a write up on Rick Oleson's site which may help:

Canon FD Lens Service

Quick note to future readers who may find this discussion before disassembling their lens: The lens does not have to be taken apart that far for cleaning the diaphragm. See the very end of my post.

I assume you have version II of the lens. You can tell apart version I from II by the green mark on the aperture ring: Version I has a green ring, Version II has a green "A". Version I also is larger and heavier than Version II. See the picture below, Version I shown on the left, Version II on the right.

In order to reassemble the lens your goal is matching three parts in two ways. The three parts are the rear lens barrel (still attached to the camera, picture 5), the double helicoid ring (picture 3 and 4) and the inner lens barrel (picture 1 and 2). The inner lens barrel has to have proper orientation to the lens mount so that the levers protruding from its rear match their counterparts. At the same time the inner lens barrel has to have the right distance from the lens mount flange so that infinity focus can be obtained.

I suggest removing the lens mount for reassembly as this will make things a lot easier: Remove the lens from the camera, move the aperture lever to the manual lock position, unlock the breech lock ring, remove three screws visible through the recesses of the breech lock ring, take off the lens mount. Caution: Two spring-loaded steel balls and the EE pin sit under the mount and are lost very easily.

You will now have to assemble the three parts in a way that gives you the configuration shown in the two pictures below.

1. The left edge of the recess in the double helicoid ring has to match the yellow index.
   
2. The inner lens barrel has to have proper orientation to the lens mount.
   
3. The distance from the inner lens barrel to the double helicoid ring (first picture) is 6.2 mm.
   
4. The distance from the double helicoid ring to the rear lens barrel (second picture) is 4.7 mm.
   

Pictures and measurements are from a lens with a serial number only 15,000 units away from your lens.

You would usually make notes of the configuration during disassembly. It does not have to be this exact setting. Any setting within the focusing range would be fine as long as you remember the parts' positions and take measurements. And you would count turns from this setting until the parts separate.

I haven't disassembled the lens as far as you did and hence cannot give you exact guidance on the next steps. It may take you a lot of try and error until you hit the target configuration. From general experience with other lenses I would start with screwing the double helicoid ring into the rear lens barrel a turn or two. Then screw the inner lens barrel in until its slots match the guides of the rear lens barrel. Then futher screw in the double helicoid ring while holding the inner barrel static until the guides slide into the slots. Now check if you can hit the target configuration. No? Try again but alter one of these parameters: Starting position of double helicoid ring, number of turns for the double helicoid ring, starting position of the inner lens barrel, number of turns for inner lens barrel. The threads usually are multi-start type and that's why starting position matters.

Next restore the lens mount, seat the front lens assembly into the inner lens barrel and restore the focusing ring. Check if infinity focus can be obtained. The shop would use a calibration device called a "collimator" for doing that. As it's very unlikely you have one available, use some sufficiently far target (moon in a clear night would be perfect) and a viewfinder magnifier. If infinity focus is just a little bit off, reposition the focusing ring (you would usually mark its exact position during disassembly). If it is far off you haven't hit the target configuration (or my measurements do not match your lens).

After completing reassembly, let us know how USD 100 now sound to you ;) (Consider the shop may not even have a copy of that lens to take measurements from...)

As mentioned at the very beginning the lens does not have to be disassembled so far for cleaning the diaphragm. My procedure would be: Remove name ring, remove front ring, remove focusing ring (mark its position), remove front lens assembly. Remove lens mount, detach spring from diaphragm lever from the rear. From the front, remove three screws and take out diaphragm base, aperture leaves and diaphragm rotor. Clean and reassemble. The aperture should be adjusted.

The diaphragm of the FD 50mm 1:1.8 SC is different from most other FD lenses. It is not a separate unit but part of the inner lens barrel. The FD 50mm 1:1.4 SSC's aperture unit for example can be removed entirely from the front without opening the rear of the lens.

After completing reassembly, let us know how USD 100 now sound to you

And HOW! This is a voice of experience. :(

Quick note to future readers who may find this discussion before disassembling their lens: The lens does not have to be taken apart that far for cleaning the diaphragm. See the very end of my post.

 

I assume you have version II of the lens. You can tell apart version I from II by the green mark on the aperture ring: Version I has a green ring, Version II has a green "A". Version I also is larger and heavier than Version II. See the picture below, Version I shown on the left, Version II on the right.

 

[ATTACH]1288750[/ATTACH]

 

In order to reassemble the lens your goal is matching three parts in two ways. The three parts are the rear lens barrel (still attached to the camera, picture 5), the double helicoid ring (picture 3 and 4) and the inner lens barrel (picture 1 and 2). The inner lens barrel has to have proper orientation to the lens mount so that the levers protruding from its rear match their counterparts. At the same time the inner lens barrel has to have the right distance from the lens mount flange so that infinity focus can be obtained.

 

I suggest removing the lens mount for reassembly as this will make things a lot easier: Remove the lens from the camera, move the aperture lever to the manual lock position, unlock the breech lock ring, remove three screws visible through the recesses of the breech lock ring, take off the lens mount. Caution: Two spring-loaded steel balls and the EE pin sit under the mount and are lost very easily.

 

You will now have to assemble the three parts in a way that gives you the configuration shown in the two pictures below.

1. The left edge of the recess in the double helicoid ring has to match the yellow index.
   
2. The inner lens barrel has to have proper orientation to the lens mount.
   
3. The distance from the inner lens barrel to the double helicoid ring (first picture) is 6.2 mm.
   
4. The distance from the double helicoid ring to the rear lens barrel (second picture) is 4.7 mm.
   

Pictures and measurements are from a lens with a serial number only 15,000 units away from your lens.

 

You would usually make notes of the configuration during disassembly. It does not have to be this exact setting. Any setting within the focusing range would be fine as long as you remember the parts' positions and take measurements. And you would count turns from this setting until the parts separate.

 

[ATTACH]1288753[/ATTACH]

 

[ATTACH]1288754[/ATTACH]

 

I haven't disassembled the lens as far as you did and hence cannot give you exact guidance on the next steps. It may take you a lot of try and error until you hit the target configuration. From general experience with other lenses I would start with screwing the double helicoid ring into the rear lens barrel a turn or two. Then screw the inner lens barrel in until its slots match the guides of the rear lens barrel. Then futher screw in the double helicoid ring while holding the inner barrel static until the guides slide into the slots. Now check if you can hit the target configuration. No? Try again but alter one of these parameters: Starting position of double helicoid ring, number of turns for the double helicoid ring, starting position of the inner lens barrel, number of turns for inner lens barrel. The threads usually are multi-start type and that's why starting position matters.

 

Next restore the lens mount, seat the front lens assembly into the inner lens barrel and restore the focusing ring. Check if infinity focus can be obtained. The shop would use a calibration device called a "collimator" for doing that. As it's very unlikely you have one available, use some sufficiently far target (moon in a clear night would be perfect) and a viewfinder magnifier. If infinity focus is just a little bit off, reposition the focusing ring (you would usually mark its exact position during disassembly). If it is far off you haven't hit the target configuration (or my measurements do not match your lens).

 

After completing reassembly, let us know how USD 100 now sound to you ;) (Consider the shop may not even have a copy of that lens to take measurements from...)

 

As mentioned at the very beginning the lens does not have to be disassembled so far for cleaning the diaphragm. My procedure would be: Remove name ring, remove front ring, remove focusing ring (mark its position), remove front lens assembly. Remove lens mount, detach spring from diaphragm lever from the rear. From the front, remove three screws and take out diaphragm base, aperture leaves and diaphragm rotor. Clean and reassemble. The aperture should be adjusted.

 

The diaphragm of the FD 50mm 1:1.8 SC is different from most other FD lenses. It is not a separate unit but part of the inner lens barrel. The FD 50mm 1:1.4 SSC's aperture unit for example can be removed entirely from the front without opening the rear of the lens.

Im sorry but I still dont get it.

I have no idea how many times I should rotate the focus ring or silver ring with the inner lens at once. Otherwise, I can not put them in one piece.

Also, there are two levers but there is no way to use the aperture ring to activate it.

I was trying to fix the aperture cause it was sticky but now, I'm not able to assemble all at one piece. It seems to be a simple work that I need to screw two pieces at once at a specific degree but I can't put them together.

 

I tried to find a manual assemble this but I couldnt find anything since nobody ever disassembles every part. I really dont wanna send this to a repair shop because they want me to charge $100 for a simple job. I just need to find a way to rotate.

 

Any information about assembling Canon FD 50mm F1.8 SC??

 

[ATTACH=full]1288690[/ATTACH]

 

[ATTACH=full]1288691[/ATTACH]

 

[ATTACH=full]1288692[/ATTACH]

 

[ATTACH=full]1288693[/ATTACH]

 

[ATTACH=full]1288694[/ATTACH]

I posted a couple threads (a LOOONGtime ago) with pictures of my own adventures in diaphragm cleaning, and although they were different lenses the process was very similar . Sadly I don't think they will help you much except maybe for the pictures, as I did not go as deep as you did. I found the Olsen article to be just about the only resource back then, along with the good folks here on the forums.

Cracking open my nFD 100mm f2.8

[PLAIN]135mm f3.5SC FD(old), bargain shop find - or idiot vs lens part 3:)[/PLAIN]

That's the extent of my knowledge, hopefully there is something there that might help. I know they are not 50's but I found the general procedure to be very similar if not the same.

How you succeed in your repair, it's very gratifying:)

I have no idea how many times I should rotate the focus ring or silver ring with the inner lens at once. Otherwise, I can not put them in one piece.

Unfortunately you will have to find out by try and error.