Help with disassembly

[Viscount]

Forgive me... this question is not about a rangefinder or rangefinder lens. I have come into posession of a forlorn Canon nFD 50mm f3.5 macro. Unlike most lenses (including most macros, in my experience) this one does not have a retaining ring with lens identifying markings. The deep, conical "hood" is all there is from the front element to the end of the lens, where the end of the barrel functions as the front rim. What I can't figure out (and can't find a clear answer on) is how to remove that conical hood. It needs some attention itself, and I would feel much better not working down in that recess to clean the front element. The rear lens complex is more easily accessed. Focusing is acceptable, and the aperture is fine.

Any and all assistance appreciated.

And, thank you for your forbearance on this being my first non-introduction post.

 

[farlymac]

The FDn Macro is one of the Canon lenses I never got, but here is a thought. I believe the cone holds the front element in place, and from a photo I just looked at there are two slots for a spanner wrench to fit in for removing it.


PF

 

[farlymac]

Okay, after looking at some more photos it appears that the spanner wrench access was added to late production lenses, as most of the photos I see now do not have the slots. So that means the front cone has a friction fit. To remove it, get something that is about the same diameter as the front ledge of the cone. Put a sheet of rubbery material (shelf liners work good for this) between the lens front and the object you've found to fit, and use that to back the cone out of the lens (turning counter clockwise). You might have to use a bit of force as Canon may have used a thread locker agent, and you'll have to break that free.


PF

 

[Viscount]

I found the same thing about the slots. I have three sizes of the rubber tools for trim rings, but haven't gotten really good bite on the cone; probably because of the square surface of the tool and the tapered surface of the cone. I'll try something with a broader surface and maybe a rubber glove wrapped around it. The cone sounds like it is plastic when I tap on it, so the safe amount of force I can apply may be limited.

Thx!

 

[farlymac]

Guess what? I do have that lens! Couldn't get the cone to break free either. It has to be a tight fit to get a good grip on it.


PF

 

[Viscount]

You may have hit the posts that I did that suggested it's glued in or that there are clips. I couldn't find a schematic anywhere.

 

[farlymac]

Not really, going mainly on experience. After a certain year most of the Japanese manufacturers were using thread locker on everything. The big problem is I forget what all I have until I start digging through the boxes

PF

 

[peterm1]

There are some tips here which may help??? : https://www.google.com/search?q=can...hUKEwjp-6fXlf3vAhUMb30KHU8zB6AQrQIoBHoECAYQBQ

 

[Viscount]

^^^^^
Yeah, I'd seen those search results. Gave it a try with a different gripper; dribbled a little lighter fluid under the rim. Nada. Got out the heat gun...nada. Decided to clean the cone as best as I could with it in place, and very carefully cleaned the front element. If I could have gotten the cone out, I think I could have accessed the front complex to clean/remove dust from the back. But Canons like to default to partially closed diaphragms, and I didn't want to work through the opening to do that cleaning. So, I buttoned it up, cleaned the outside up and tested it out (sharp!) so I'll probably set about finding it a new home.

 

[farlymac]

Good to hear it's a good lens, and you don't have to do anything else to it.


PF

 

[BernardL]

I have three sizes of the rubber tools for trim rings, but haven't gotten really good bite on the cone; probably because of the square surface of the tool and the tapered surface of the cone. I'll try something with a broader surface

If I were in your situation, I would
a) ensure a larger contact area between tool and lens ring;
b) use double-sided adhesive tape between tool and ring; first the normal one (e.g. to fix carpeting to floor), and if not sufficient, t strong one, foam, used, e.g. to fix a mirror to the wall.

Once the ring is off, you'll find a way to remove the tape.

 

[seany65]

I usually find a big hammer helps with disassembly...