Disassembly steps for cleaning front and back lens elements
CANON FD 50MM 1.8 Lens
1. REMOVE FRONT NAMEPLATE
Use a plastic wedging tool to lift the filter plate. Be careful not to scratch the front element.
2. CLEAN NAMEPLATE
The front filter nameplate is plastic. Put this under running water to clean any gunk off it.
3. REMOVE 3 SCREWS
The 3 screws hold the front filter and secures the front lens group.
4. CLEAN FILTER RING
Clean the filter ring under running water
5. REMOVE FRONT LENS GROUP
Slowly tip the lens over and the front lens group will slide out
6. REMOVE RETAINING CLIP
Use a thin stiff blade to remove the plastic clip
7. TAKE A BREAK
The front lens group should like this and is ready to be separated
8. SEPARATE LENS GROUP
Use a suction device to separate
9. CLEAN LENS
Use a Qtip and clean the back of the front element with lens solution. 91% isopropyl alcohol is mild enough on these lens coatings.
10. CLEAN FOCUS RING
Use a Qtip and work around the inside of the focus ring
11. INSPECT APERTURE BLADES
Mount an adapter to allow adjusting the aperture. If blades show any signs of oil, clean them with a qtip. Be very gentle!
12. INSPECT REAR LENS GROUP
Open the aperture all the way and inspect the rear group. Clean the lens that exposed behind the aperture if required
13. REASSEMBLE FRONT GROUP
Reverse the steps to reassemble the front lens group. You can disassemble further if you want to clean the helicoid, but do this at your own risk.
14. REMOVE 3 MOUNT SCREWS
Flip the lens and remove the 3 screws holding the mount to the lens
15. REMOVE MOUNT
Attach the adapter to the lens and rotate to lock into position. Pull-on lens adapter to separate metal lens mount with the lens
16. CLEAN MOUNT PLATE
Removing the metal mount and the lens should appear as above. Clean the gunk
17. CLEAN METAL PLATE
Leave the metal mount on the adapter. Use a qtip to clean it
18. CLEAN AREA AROUND LENS
Clean the area around the rear lens group
19. REMOVE RETAINING CLIP
Use a stiff blade to remove the retaining clip holding the rear lens elements. Wedge in and lift, don't use to much force.
20. CLEAN RETAINING CLIP
This is how the clip looks if you haven't destroyed it.
21. CLEAN REAR ELEMENT
Carefully flip the lens and the rear element should drop out. The curved side is the one that should be facing the outside of the lens.
22. CLEAN INSIDE REAR ELEMENT
This element can also be removed for cleaning but you can just leave it in current position and clean from here
23. EXAMINE REAR PLATE
Examing the rear plate so you are familiar with how to line up the levers. This is the hardest part of reassembly.
24. POSITION LEVERS
The levers need to be in this position for the mount to reattached. Pay attention to the highlighted area. Use a flat screwdriver to move the black circle so levers can be moved into position
25. POSITION LEVERS 2
Use a paper clip to push the level and hold it into position. You can also just use your fingers.
26. LINE UP LEVERS
The highlighted part need to be mated together
27. LINE UP LEVERS 2
The highlighted part needs to be mated together
28. ATTACH MOUNT PLATE
If you have lined things up correctly, it should sit flush and look like the above
29. ATTACH METAL MOUNT
Line up the 3 holes with the metal mount. Push the mount down until all 3 are aligned. Fasten screws