Documentation for Canon FL 55-135mm f3.5

[MainFrame]

This question is for the old-timers.

I was recently gifted a lovely Canon FL 55-135mm f3.5 lens.

The aperture mechanism is not functioning.

I've looked high and low for some instructions on how to disassemble the back of this lens to reach the problem.

Does anyone have a pointer to the service manual for this lens?

[Mark35mmF2]

Hey There MainFrame,

This one is going to be tough to find, the FL mount even precedes the slightly updated FD mount we saw in the 1980's. Your best bet might be eBay for a repair manual on this lens.

One thing to keep in mind, however: The FL and FD lenses will not stop the aperture down without being mounted onto a camera body, so in case you are only checking the lens while it is unmounted, you may want to mount it on your FL mount camera, set the shutter speed to "B" and check the aperture with the film door and shutter open to verify that the aperture mechanism is indeed inoperative.

[RobertTheFat]

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@Mark35mmF2 wrote:

Hey There MainFrame,

This one is going to be tough to find, the FL mount even precedes the slightly updated FD mount we saw in the 1980's. Your best bet might be eBay for a repair manual on this lens.

One thing to keep in mind, however: The FL and FD lenses will not stop the aperture down without being mounted onto a camera body, so in case you are only checking the lens while it is unmounted, you may want to mount it on your FL mount camera, set the shutter speed to "B" and check the aperture with the film door and shutter open to verify that the aperture mechanism is indeed inoperative.

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Presumably the reason the lens doesm't stop down by default is so that the full aperture can be used for focusing if the lens is mounted on an SLR. So an even more straightforward way to verify the lens's functionality on an SLR would be to set a small aperture and then depress the preview button (usually on the front of the camera near the lens) while looking through the camera's viewfinder. You should see the image suddenly become darker if the aperture setting mechanism is working correctly.

[kvbarkley]

Correct me if I am wrong, but you should be able to push the little pin on the flange to activate the aperture, no camera required.

[RobertTheFat]

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@kvbarkley wrote:

Correct me if I am wrong, but you should be able to push the little pin on the flange to activate the aperture, no camera required.

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Unless the mechanism is electric. And on a lens that old, it almost certainly isn't.

[ebiggs1]

"Unless the mechanism is electric."

Nothing electric!  It should have a A and a M setting ring.  In M you should be able to move the aperture ring and see the blades open and close. The big difference is the FL is a breech mount. There is also a variation of the fL mount lens, the SSC.  In it you can't move the aperture blades with out a camera. Disclaimer, this is ancient tech so I had to dust off brain cells that have not woken up in decades. It is the best of my remembrance but I do have several holding a shelf down and doing a marvelous job!

BTW, I am sure Ed Mika makes or used to make a FL to EOS adapter. The adapters of his I have used are very good.

[kvbarkley]

Looking at the pictures, it has the little tab so that you can focus at full aperture and stop down for preview or exposure, so you need to push the tab/pin to activate the aperture.

[ebiggs1]

If it is an FL not an SSC the aperture ring will work with the M setting.  (If it isn't broken that is)