Hi! I recently bought a nice praktica Super TL with an Oreston 1.8/50. What i've noticed is that when the shutter is depressed, the lens diaphragm closes and opens at a fast speed which seems constant, unrelated to the shutter speed. For example, with a shutter speed selected at 1/4 sec or slower where the problem is easiest to observe, the diaphragm will stop down to the selected aperture when the shutter is depressed, but it will open again BEFORE the shutter closes, i.e. the shutter is still open when the lens aperture goes wide open again. Looks like there is no synchronization between the shutter and the diaphragm. This happened with every auto lens i tried, the Oreston behaved normally on my Yashica TL Super. However if you press the shutter release and keep it pressed, the diaphragm stays stopped down throughout the exposure. Is this normal? Certainly, if the diaphragm opens up before the shutter closes, the picture will be overexposed? If the lens has a manual setting this can be avoided, but what if there's no manual switch? Thanks.