- The ENTER key on a calculator is a clear sign that it employs the Reverse Polish notation or RPN method to evaluate mathematical expressions. My first RPN calculator was the 1978 model HP32E which I owned and used for over 20 years. My first serious programming was done on an HP41C, basically a handheld computer which was also used as the third level backup system computer for the first nine space shuttle missions. It's always fun to hand your RPN calculator to an unsuspecting victim and watch them search for the nonexistent "=" key - its a geek thing. Canon 40D, 1/500 sec @ f/2.0, 50mm macro lens.
From 365 Project The Air Force Memorial in glows against low hanging clouds and mist. Located on a promontory in Arlington, Virginia, overlooking the Pentagon and adjacent to Arlington Cemetery, the memorial's three 270 feet tall stainless arcs evoke the spirit of flight. Taken with a Canon 40D, 5.0s exposure at f/8.0, ISO 200, 28mm equivalent focal length, mounted on a tripod.
This is a reproduction on an early 20th Century "squirrel cage" carbon filament light bulb built by Thomas Edison. In today's modern reproductions the filaments are made of tungsten, which burns three times brighter than the original carbon filament versions. They are really getting popular in vintage bare blub fixtures. This one was hanging over my table at Tarrant's Cafe , 1 W. Broad Street in Richmond Virginia. Canon G15, 1/15 sec @ f/8.0, ISO 200, in macro mode.