"There is a PK-11 and a PK-11A which are much shorter tubes and the PK-11 DOES interfere with electronic connection block and should not be used on AF- lenses and cameras."
Use a PK-11A on any D-SLR when you need a small amount of extension (to focus closer).
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My significant other (Deborah Allen) used it as a spacer between two teleconverters so get extra reach for telephoto les (at that time a 500mm F4 AiP lens).
"There is a PK-11 and a PK-11A which are much shorter tubes and the PK-11 DOES interfere with electronic connection block and should not be used on AF- lenses and cameras."
Use a PK-11A on any D-SLR when you need a small amount of extension (to focus closer).
=================
My significant other (Deborah Allen) used it as a spacer between two teleconverters so get extra reach for telephoto les (at that time a 500mm F4 AiP lens).