On FD Lens - Question

[my_photography]

I only have 1 FD lens and was just testing out when I realised the diagram does not change when I change the aperture. Is this normal for FD lens?

[marty]

Hi. there. No fear, that's normal behavior. When dismounted from the camera the iris usually stays half way closed, opens up all the way when mounted and closes to the selected aperture during the release cycle then goes back full open at the end of the exposure.
Edit: the adapter takes usually care of locking the mechanism so it's manually operable.

Cheers, M.

[my_photography]

Any method to see the iris movement when the lens is dismounted from the camera?

[joy division]

on the backside of the lens, you should see a flange. if you push it against the tension of the spring, you can see the aperture blades close if you don't have the aperture wide open.

[koji]

Or you can use a Canon FD lens rear cap, you can see the iris can close when you rotate its aperture ring.

(When you go to the used lens shop in Japan, they supply a lens rear cap with a big hole in its bottom, so that
you can inspect iris movement easily. The rear cap press two metal things on the lens to release the aperture lock,
I think Canon "over-engineered" FD mount.)

[my_photography]

[scsambrook]

Sounds as though you may have the later style of FD lens which doesn't have the rotating breech-locking ring. If so, joy division's suggestion wont actually work. A rear cap will do the trick though.

[my_photography]

I am in the process of getting a FD lens. So I asked the seller to test the lens with the back cap since he does not have a FD Canon. I asked him to screw on and screw off the lens on the cap to see the movement of the diaphragm. Here is the answer I got: "with the back cap, the diaphragm move a little bit when i put on or off the cap. But there s not a real change when i turn the ring of diaphragm." Should I be worry? Is there anything wrong with the lens?

[koji]

Probably not (to worry or a bad lens).

When a rear cap is on, AND then you have to move the taller aperture linkage back and force
after setting higher f-stop (wide open wont change anything). There are two aperture linkage
bars behind the lens, you have to move the taller one, shorter one wont move anyway.

So your rear cap must have a big opening or the lens should be mounted one of those
FD->E adapter or FD->m4/3 adapter which have opening.

So checking FD lens at the store front is not easy thing unless you have FD camera or a special
rear cap.

According to your corresponding guys's description, the lens might be totally OK. But the above
method is a sure thing.