Dear Les,
     Aaaaaakk.
     Okay, now I have overcome my initial fears....What kind of optical
result would I get unscrewing the front element of a 150 Symmar S? I have
undone it all the way for interesting focal length changes, but never just a
half a turn. Off to experiment.
     Uncle Dick
PS: Do scientific confectionary manufacturers make up batches of
experimints?