Canon FD 28mm f/2.8 won't attach

Started Nov 6, 2012 | Discussions thread
photonius
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Re: Canon FD 28mm f/2.8 won't attach
In reply to samuraidave, Dec 25, 2012

samuraidave wrote:

Thank you so much for your help, everyone. I just today got my small screwdriver set so I took the lens apart, and now the silver bayonet attachment ring moves! However, I'm stumped as how to line up the spring loaded levers. No matter what I do I can't seem to get it so the aperture ring makes any change. The larger lever on the rear is doing its job fine though, and the smaller lever moves also. Just no change in aperture. I'm also not sure what position the little steel ring with a hook on it should be in. This is the piece that surrounds the center glass. It has 3 possible positions, and I am not sure which.

With the disassembled lens, I can't help. perhaps something is in the wrong position.

Anyway, as to how an FD lens should work.

The large lever is the one that the camera body moves to stop down the lens to the effective aperture in A (auto) mode.  So, it has only two positions so to speak, open, or stopped down. In the stopped down position, the aperture may of course still be open, if the exposure system of the body asks for open aperture (say, f1.4). This lever, if used on for example, a bellows, or any other full manual way, where no body or other system can stop down the lens, must be looked in the "stopped-down" position. To lock it, you push it until it clicks into the locked position. You can also push it into the open position again, if manual mode is not necessary anymore.

The short lever: this is the lever where the body sets the aperture. So, if the body asks f4 from the lens, a lever in the body will push this short lever to f4. The lens still remains at the open aperture however, until the shutter is released, the the body stops down the lens via the large lever.

So, far, so good.  To use the lens in manual mode, lock the large lever in the stop-down position. Move the aperture ring from A to any desired aperture, say f4.  Big Note: this works only when the lens is mounted. For some reason, the aperture movement is linked with the silver breech mount.  If the lens is in manual mode, stopped down, but not mounted, it will not work. To make it work, you will have to release the mount ring by pressing the little lever under the mount at the red dot position. You will notice that the aperture opens/closes as you move the silver mount ring (depending on manual setting of the aperture ring, say f4). To get the full range of aperture movement (say from f1.4 to f16), the mount ring must be fully closed as it is when mounted on a body.

So, the latter issue is maybe something that confounded you. However, another possibility is that something is broken with your lens, or that when disassembling/reassembling, you somehow didn't link breech lock and aperture correctly.

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