The F4S I recently bought makes a high-pitched noise when I press the DOF preview button and when it stops down the aperture prior to an exposure, even without a lens mounted. It sounds like something is rubbing against a tightly wound coil spring or fine pitch threads on a screw. It works fine, but I'm concerned that the noise is not normal; I don't have another F4 to compare it to. I don't recall ever hearing an F, F2, or F3 make this sound. Is it normal for an F4? Advice is appreciated. Neal [EMAIL PROTECTED] Florida, USA