Diaphragm does not close

Discussion in 'Canon FD' started by flolaco, Oct 15, 2017.

  1. Hello all,

    I bought a canon AE1 (not program) long time ago, and I discover that diaphragm is not closing when i trigger the release button.

    My lens is an old FD 85mm S.S.C with no release button and a chrome ring. And the battery is good.
    I also try to "play" with the diaphragm of the lens when it's unmount. I move the "spindle" (or lever) (at the opposite side of the red point) and the diaphragm is closing well.

    What I do :
    I put the aperture ring to f16, I put the shutter speed to bulb. I arm the camera.
    I open the backside of the camera with no film to see what's happening through the lens.
    When I shoot and stay the button press, I see that the diaphragm is not close.
    I suspect the "diaphragm control lever" (cf page 2 of this service document on this page) because I see the control lever still at the top.
    And when the control lever is still at the top, one of the spindle/lever (the spindle that move when I lock/release the lens from the camera) of the lens is also at the top, which prevent the diaphragm to close.

    I did a second test :
    I put the aperture ring to f16, I put the shutter speed to bulb.
    I arm the camera and I open the backside of the camera with no film to see what's happening through the lens.
    But this time, I action the "stopped-down lever", I see from the front of the lens that the diaphragm is now close (finally). I release the "stopped-down lever". Then now I shoot and stay the button press, I see that the diaphragm is close and the "diaphragm control lever" is down !
    Perfect !
    If I shoot again but with no "stopped-down lever", the diagram will not close again.

    So, why the diaphragm is not closing ?
    I have to tell you that the exposure mesure is not functioning, the needle is always go down, even with a lot of light
    Thanks a lot
  2. Does the problem only happen with the FD 85mm, or with any FD lens? Also try this. Take off the lens and look into the camera's mirror box. You'll see a lever on the right side of the mirror. It should be resting at the top. This lever is spring loaded and should move down as you push it and return to the top when you release it. See if the lever is indeed moving freely.
  3. I only have this lens.

    The lever on the right (the diaphragm control lever) is impossible to move with my hands. I can't move it freely.
    What I see about this lever is :
    - When I "charge" the camera, this lever is moving about 1mm approx (but is not moving down, and if I touch it at the same time, it's still impossible to move it)
    - when I charge de camera then I engage the stopped-down lever, I can move the diaphragm control lever freely.

    So, this lever should move freely when the camera is not charge ? And when it's charged ?
    I think it's should not move freely because the mesure is happening at the full apperture. If it's moving freely, the diaphragm will close.
  4. I have an FD camera facing me. You have two levers that affect the way the camera and lens operate. Actually, there are three, but I'm not gonna get into the third because it doesn't matter in this context. That lever on the right side that moves up and down is your full-aperture metering lever. It indexes with the lens to tell it how far to stop down during the moment the picture is taken. Along the bottom of the mount area is another lever. This is the important one. This is the lever that actually stops down the lens at the moment the picture is taken. When facing the camera, this lever moves from right to left. As it does so, it uncovers a red dot.

    With my camera -- an FTb (I have an AE-1 downstairs in my camera cabinet although it should work the same) -- both levers move freely whether the camera is cocked or not. Only the bottom lever moves during the moment the picture is taken. It moves very rapidly from right to left and then back right again. But this is a manual camera. With the AE-1, the side lever may pre-position itself for proper exposure. I'm not sure. But the important thing is that neither lever is locked in place.

    Since you have at least one lever that is locked in place on the camera, it is that mechanism that I would consider to be at fault. Good news is it's repairable. Bad news is the repairs will likely cost more than the camera is worth. I would consider a repair or replace strategy, and the possibility of purchasing another AE-1 through a reputable dealer that offers a warranty, or at least a return option. You might want to consider an upgrade to the AE-1 Program too. In addition to having a Program mode, which the AE-1 lacks, the AE-1P has user-interchangeable focusing screens and a motor drive option (Motor Drive MA), whereas the AE-1 has a fixed focusing screen and takes only the Winders A and A2.
  5. Thanks for your reply.

    About the lever on the right. From my point of view, I think it should move freely. The lever of the lens is making a counterweight on the lever of the camera. The lever of the lens have multiple position, one for each aperture stop. This is this mecanism that tell the camera which aperture I've choose from the ring. But because I have no other AE1 (working) front of me, I can't be sure.

    The purpose of this lever is only to close the diaphragm, right ? Sorry I didn't understand what did you say "actually stops down the lens".
    For me, the red dot should be cover (mask), not visible. If the red dot is visible, it means that the lever is engaged.

    Is it possible to you to confirm me that, both levers is moving freely or lock, when camera is cocked or not ?

    Thanks you for your advice about buying another one, especially the program version.
  6. Yes, the lever to the right of the mirror should move freely. As you change apertures, this lever will connect to an adjoining lever on the lens and “ride” on it. It tells the camera what aperture the lens is set to. When the lens is set to “A,” it works in reverse, the camera then tells the lens what aperture to use. I brought this up in an earlier post because it relates to your other problem, which is that your meter appears not to be working.
  7. So the meter is not working because the lever can't move ?
    It's weird because :
    - If it stay at the top, it means that my apperture is 1.8, so if I do the mesure into a black room, it should tell me that it's okay, but it's not ...
    - If I use the "stopped-down lever", this lever is working again, so the mesure should work on this case, but it's not.
  8. What happens when you set the lens to “A”? The needle in the viewfinder should move up or down depending on the light. And the lens aperture should stop down to whatever aperture the camera sets.

    With all of your problems, your camera could be toast. With AE-1’s being so cheap, it maybe just better for you to pick up another one.
  9. The needle is moving to the extreme down, and the red dot is blinking. And when I trigger, no diapgram is closing.
  10. The red dot blinks to warn you your exposure is wrong. Try this. Set the ASA to 100, put the lens on "A," set the shutter speed to 1/125, go outside, press on the shutter button, and see what the exposure is. Depending on the light, the needle should point to F5.6 or something close to that. If the needle still hugs the bottom of the viewfinder, and a red dot is still flashing, your camera is messed up. As for why it doesn't stop-down, the only suggestion I have is to try another lens on the camera. This will tell you if the problem is with your 85mm, or the camera.
  11. Vincent Peri

    Vincent Peri Metairie, LA

    Well, in full sunshine, more like F/16...
  12. Not really. Point a reflective meter at a black car in the sun, and it won't read F/16.

    The point being the meter should read to a F-stop, and not hug the bottom of the viewfinder with a red blinking light like what is happening to the OP.
  13. Why would you point a meter at a black card? Jim is quoting the Sunny F/16 rule, and he is correct. Proper exposure in sunny conditions at ISO 100 is 1/125 @ f/16. If you read an 18% gray card that is well illuminated in bright sun conditions, it will give the Sunny F/16 reading. Your suggestion is more for deep shade. Still, what you're suggesting isn't out of line. The meter needle definitely shouldn't be bottoming out and the red LED should definitely not be blinking. Time for a repair -- or another camera.

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