Aperture lever stuck to wide open

Set the exposure mode to "M" (Manual). You'll have to set both the aperture and shutter speed yourself.

You'll also get no exposure assistance from the camera's light meter. You can review the picture after taking one and/or use the histogram to tune the exposure.

You must lock the aperture ring to f/22, so the camera can engage the aperture adjustment lever on the lens. Then, you can change the aperture with the command wheel.

When you change the aperture with the command wheel the aperture ring on the lens doesn't move when the camera actually adjusts the lens aperture.

Take the lens off and locate the aperture adjustment lever on the lens mount.

Unfortunately, this won't work with older AF lenses. So if you are using an older lens, the only thing you can do is change the camera setting to M (Manual) to adjust the aperture on the lens yourself.

I think the aperture is not shutting down to the opening you set it to. In an SLR, the aperture is normally fully open for viewing through the lens. When you press the button, the mirror flips up and the aperture closes to the figure you have set, then the shutter fires. If you have set a daytime aperture and the aperture sticks, you get a wide open aperture and an overexposed shot, but at night, you have set an open or almost open aperture anyway.

It is possible that the shutter is the problem, but the aperture is more likely to go wrong in my experience. It only takes a drop of oil on the blades. There ought to be a button or lever to shut the aperture down for depth of field preview which you could use to test this, or just look in the lens when the shutter fires to see if the aperture closes.

You probably have to set the aperture manually on the lens, because it might not have CPU contacts. I think changing the aperture on the camera will probably have no effect, so just try twisting the aperture ring to wide open.

You usually have to set the aperture at the minimum setting (highest number) so that if the camera is choosing the aperture, it can stop down to the required value.

No good having it set at f2.8 if the shot needs f11.

If the lens is very old, it might have a manual iris that you have to set yourself on the lens. The lenses that stop down automatically will have a tiny peg on the mount that a suitable camera can operate. Gentle pushing of this peg while looking through the lens will tell if it is stopping down - set it wide open first.

If you have a depth of field preview button, this will also have the same effect with the lens on the camera if the body matches up with the lens.

You are correct that the switch locks the aperture. In order for your camera to function correctly in the auto-focus mode you must lock the aperture to the smallest opening (largest number such as f22). The switch has two positions. The position where the switch is lined up with the orange line is the locked position. When the lens functions properly and on the camera, the lens aperture is forced wide open by a pin on the camera body pushing a lever on the lens that opens the aperture. As part of the sequence when you push the shutter button, the camera releases its pressure on the spring-loaded lever on the lens, allowing the aperture to close to the setting that the "computer" has determined as correct. You will find this lever on the outside of the black ring that surrounds the rear lens element. With the lens removed, find the lever and make sure that with the lens set to the f22, sliding the lever counter-clockwise against the slight spring tension, the aperture opens wide and returns to f22 when released. If this is not the case, the problem is in the lens. If this works, then the problem is either in your camera body or in the alignment between the body and lens. If this does not get you on the right track, let me know what you find and we will proceed from there.

You have a case of AE(auto exposure) Unit faulty or getting bad. It suppose to register as it move within the AE unit according to the exposure calculation but somehow it is broken. Technician usualy replace the AE unit and takes care of the problem. It can also be rebuilt if new parts are not available. This requires complete disassembly and mirror box removal. The average cost of repair probably runs around $100. Yes, "A" mode is correct for most of the shots and it was a state of art electronic system and more computerized than you think. It has 3 IC chips in there for precessing and 1 chip for the exposure. All works together for good. -James

I would start to diagnosis the problem as follows: When the lens functions properly and is on the camera, the lens aperture is forced wide open by a pin on the camera body pushing a lever on the lens that opens the aperture. As part of the sequence when you push the shutter button, the camera releases its pressure on the spring-loaded lever on the lens, allowing the aperture to close to the setting that the "computer" has determined as correct. You will find this lever on the outside of the black ring that surrounds the rear lens element. With the lens removed, find the lever and make sure that with the lens set to the smallest f-stop (largest number such as f22), sliding the lever counter-clockwise against the slight spring tension, the aperture opens wide and returns to f22 when released. If this is not the case, the problem is in the lens. If this works, then the problem is either in your camera body or in the alignment between the body and lens. Also, the electrical connection between the camera body and the lens is via the five little ball like metal contacts (4 together and one wider spaced) found on the black ring on which the aperture ring is located. If either these contacts or the contacts on the camera body are dirty, the automatic functions may fail. DO NOT use any liquid cleaner. Gently rub the contacts with a rubber pencil eraser, being very careful to hold the camera body or lens in a position that will allow any debris to fall downward away from the body or lens. Do not overdo it. If this does not get you on the right track, let me know what you find and we will proceed from there.

P.S.: Have you made sure you have fresh batteries in the camera?

It does sound like your lens diaphragm/aperture ring coupling mechanism is in need of repair.

The lens has a lever marked A/M near the aperture ring. If the lever is in the 'A' position, the lens will stay wide open until you trip the control lever at the back of the lens next to the rear optics. In the 'M' setting, you can see the aperture move as you change the f-stop setting on the ring. Set the lens to anything but wide open and move the control lever with your finger. You should see that aperture move.

They will - fully open in Av mode, and with any aperture in manual mode - after you allow the Ds through the custom settings menu to use aperture settings different then "A". To choose correct exposure with such a lens in manual mode you can use the AE-button - it stops down the aperture, reads the EV and sets the shutter speed according to the chosen aperture.