I'm looking at a Vivitar 2x AF teleconverter for general use now & then. Obviously cost is an issue or I wouldn't be looking at Vivitar. I assume AF is auto focus. Any comments ?
I'll add my two cents. Having worked for Piper Aircraft Corp. in Lock Haven, PA, for 21 years the aircraft registration number (tail number) was refered to as the "N" number of the aircraft.