I recently gave my “Movement in Photography” talk to the Facebook Camversation group. It was great to talk to about 100 photographers from around the world. One subject of my talk was the “Harris shutter”.  It’s a technique developed by Bob Harris, a Kodak engineer, and involves taking a three exposures on one film frame using three coloured filters; red, green and blue, and with one exposure per filter.  The idea is that where no movement has happened the colours come out normal, and where movement has happened you get red, green or blue colours appearing.  You also get the additive colours where these primary colours overlap.  It’s a fun…