Ed,

It sounds as though a slight trace of oil has found its way onto the iris blades and this causes the sluggish action, leading to overexposure. I suggest you get the lens looked at by a camera technician.

By Ed on Sunday, August 31, 2003 - 10:15 pm:

I've got a 645 1000s w/ standard 80mm, the apeture is sticking as i try to stop it down either when the lens is set to M or when using the depth of field preview. I opens out again fine but needs coaxing to the smaller apetures. Seems to work as the shutter fires, but i don't know how much longer for... Any one come across anyhting similar?

Ed