Originally posted by JohnBee Wow... I must really be loosing my mind, because I could of sworn(up and down) that my K lenses all responded to the aperture ring manually without stopping down... in fact... I could or sworn that I was using it just recently on a scenery shot at f11 thinking... wow! an I ever glad I don't have to force focus because the screen is so dark. In fact... I know the viewfinder was dark due to the ring setting!
Therefore, am I to conclude that there was something wrong with my camera prior to today or am I going mad?
PS. I've been on allergy medication for a few days now. I guess its taking its tole on me
You are going mad. Might be the allergy pills too (same difference)...lay off the Benadryl for a week and then see how it works.
All K-mount lenses focus/compose wide open on your dSLR unless the aperture lever has been physically removed or chopped off. Your non-A Pentax-K lenses should only stop down at exposure time, when green button metering, or when using the optical preview feature and then only when the camera is in M mode.
To make it easier:
- Examine one of your Pentax-K lenses with back cap off when it is off the camera
- It should be stopped down to the aperture set on the ring
- Manually move the aperture actuator lever
- The aperture will change to full open
- When you mount the lens on the camera, the lever engages the coupler in the body and opens the lens
- When an exposure is made with a non-A lens, the coupler releases the lever to stop the lens down to the aperture set on the ring just prior to exposure and engages it to open the lens back up after the exposure is made
- When you engage the optical preview, the coupler does the same thing to stop down the lens
Note that this action is somewhat different when the aperture ring is in the "A" position on lenses that support that feature. On those lenses, the lever moves the appropriate amount for the aperture set by the camera body.
As for testing that the aperture is stopping down at exposure time...That is easy. Stop the lens down to f/8 in M mode with the shutter speed at 1s. Look into the front of the lens while doing the exposure. You should see the lens stop down and reopen. Put the camera in P mode and do the same thing. The lens should remain wide open for the duration of the exposure.
If the lens does not stop down for exposure in M mode, there may be a broken linkage in the lens. Check that the lever works the aperture properly when the lens off the camera. On some older film cameras, it was possible for the arm to slip past its coupler if misaligned. This is not possible on your K20D. The only way for the lever to fail to engage is if it has been shortened (snipped/sawn off) at some time. There is an outside possibility that the lever might be bent over enough to jam outside its gate on the body leaving it wide open at all times, but this would be very unusual.
If your lens is always stopped down when mounted to the camera and there is nothing wrong with the lens, there is something wrong with your camera.
Steve