Hi everyone. I picked up a cheap Bower 300 mm f5.6 telephoto lens that seemed to have a M42 screw mount. It is not a M42 nor is it a T mount. When I measure the outside thread of a M42 mount with a digital caliper I get approx 41.77 . When I measure this one I get approx 42.6. Remember it's a screw on mount and it's bigger that a M42. BTW I use a Lumix GH1. Is there anyone out there that might have a clue what type of mount this may be ?