Originally posted by igowerf I assume by "bayonet" you mean that aperture lever? My Super Takumars have those and they also have a switch to choose between Auto and Manual aperture. In Manual aperture mode, the aperture closes down when I turn the aperture ring. In Auto mode, the aperture stays open while I turn the ring.
Huh? M42 lenses - like your Super-Takumars - do not have a bayonet. They have an auto-manual selector for stopping down or not, but 'auto' only works on M42 cameras. Leaving the lens in auto mode will keep it wide open the whole time.
Originally posted by igowerf The AE-L button should still work regardless of whether the lens has an automatic aperture or not because the camera will meter based on what it sees when you hit the button. If he wants to adjust the shutter speed, he'll need to be in M mode.
Yes, the AE-L button will work with M42 lenses. But you don't need to use it - you will get the same results in Aperture Priority mode. Why do an extra step when you don't have to?
I understand what you're saying - because with M42 lenses, shutter priority mode doesn't change your shutter - M mode is the only way to force the shutter to a set value. But you'll need to make sure the lens is at the right aperture anyway, so I see no utility whatsoever to shooting with M42 lenses in M mode.