Canon FD: Aperture blades not moving

Odot · Oct 18, 2016

So i got this new-er version of the FD 50mm 1.4 and it appears that the aperture blades are not moving, regardless of the setting. With my 28mm, i was able to set it to F16, set the shutter speed to bulb, keep the shutter button pressed and hold to see if it would stop down/move at all and it did.

This sucker here only moves when i put it on the camera, the moment right before it locks in to the camera (lack of a better word). Thats when i see the blades move. As soon as it locks in, the aperture blades disappears off the lens. Is this normal?

AgX · Oct 18, 2016

That is the way it goes with New-FD lenses.

Whereas the old version behaves normal, thus the aperture is open and can easily be closed by moving the automatic-diaphragm actuator, the new lenses have the aperture locked at F 5.6 or so.
The aperture only opens when set onto the camera, or when the rear cap is attached and locked.

To be true also with the the old version one has to set the breech-lock ring to the "fastened" position to manipulate the aperture.
Basically you have to do the same with New-FD version.

As with the old one where you have to unlock the breech-lock ring by just twisting it a tiny bit and then take off the rear cap, before twisting it to the "fastened" position, you do basically the same with new version.

Only differences are that it is slighty more fiddly, that you now twist the mount (as there is no breech-lock ring) and that there is quite a resistance to overcome.

Odot · Oct 18, 2016

thanks a lot for the info, cant wait to shoot a roll.

Theo Sulphate · Oct 18, 2016

To ensure the aperture blades are not only moving, but moving quickly enough, this is what I do (regardless of lens manufacturer):

- Mount lens on camera, set to minimum aperture (e.g. f/16).

- Set camera to fastest (shortest) speed (e.g. 1/1000)

- Open camera back, cock shutter, point camera at bright sky or brightly lit surface, then trip the shutter

- You should briefly see the fully closed aperture. If the blades are sluggish due to oil, then the aperture won't close down fast enough at 1/1000. If the shutter is capping, you won't see anything.

I've found numerous problems this way when browsing camera shows.

AgX · Oct 18, 2016

A much better test on the working of the aperture blade is the way I indicated above, as
-) you do not need a camera unloaded, only that cap, that one typically has in the bag
-) it yields more information

Anyway, the working of the blades should be tested regularly, a hint I never ever read in any textbook.
Surprising, seen how many defect aperture mechanisms I came across (in different mounts).

benjiboy · Oct 18, 2016

FD new type lenses just need to be put on a camera, set to the smallest aperture and press the stop down lever.

AgX · Oct 18, 2016

Yes, by this you can use a camera loaded with with film for control of action of the blades.
But still sthis way control only can take place indirectly by the luminance and sharpness of the finder image.
To me the only control works via manually manipulating the automtic diaphragm actuator.

flavio81 · Oct 18, 2016

Odot, what AgX said was correct.

Welcome to the wonderful world of Canon FD system, where all your photographic dreams come true. The FD 50/1.4 is an excellent lens, right up with the very best of the 50/1.4 lenses, except maybe for the Leitz lenses.

AgX · Oct 18, 2016

-) the free run of the aperture blades is best controlled directly at the lens via the automatic-diaphragm actuator

-) a basic test on the aperture closing and coupling to the camera can be done after coupling the lens to a body and view through the finder whilst using the DOF button

-) a test on the transfer of the aperture setting to the body can be done by looking at the meter/display
The same for the auto/manual actuator.

-) a basic test on the body actuating the automatic-diaphragm actuator and the aperture-setting actuator can be done by releasing the camera and changing the exposure setting whilst looking into the lens, watching the aperture.
If setting the camera at multiple-exposure or disengaging the transport gear this all even can be done with film loaded, only sacrificing one frame.

-) a better test would be a exposure series over all aperture/speed combinations

Canon FD: Aperture blades not moving

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