I would go for super-simple and cryptic.
The focal plane symbol (circle with a horizontal bar through it) is cool.
You could also use the triangle with cut corners to represent silver halide.
The Leica winged arrow that's on the knob film advance of Barnack cameras.
A doublet (cemented positive+negative lens) is a great symbol, part of the history, and declined by many lens manufacturers (Leitz, Schneider, Zeiss)
The russian optical factories have really nice logos as well (here's a list:
http://cameras.alfredklomp.com/logos/)
Or you could just use a photo of
this guy.