Trigonometry for photographers, or not
The photography world learned yesterday the sad but not entirely unexpected news of Henri Cartier-Bresson’s demise. Cartier-Bresson was 96 years old, and had prepared his legacy by setting up a retrospective and foundation in Paris. The catalog of the retrospective is one of the finest coffee-table books you can get, by the way. Cartier-Bresson is best known for his theory of the “decisive moment”. Although some wags would say the decisive moment was really when he reviewed his contact sheets, Cartier-Bresson clearly perfected a technique of anticipating the event and being ready to capture it on film, helped in this by his Leica rangefinder cameras.
Cartier-Bresson was known for his caustic wit and his often provocative statements. In an interview to Le Monde, he derided the “academic clichés of Weston” (les poncifs académiques de Weston), referring no doubt to Edward Weston’s still life studies of peppers. Someone using lightweight equipment like Cartier-Bresson has the luxury of spontaneity large-format photographers like Weston did not. Indeed, Brett Weston, Edward Weston’s second son, quipped that “Anything more than 500 yards from the car just isn’t photogenic” when working with a 8×10 view camera.
You don’t have to carry a behemoth camera to realize the virtues of forward planning. When doing landscape photography, it is helpful to know ahead of time what kind of lens or camera to pack, and the position of the sun. There are many ephemeris tables online to find the latter, but the easiest way to select a lens is to use a map. You could use a protractor to measure angles, but they are relatively small and fiddly to use. As I often shoot with a Fuji G617 panoramic camera and a Hasselblad system, I made a series of translucent templates to help with this – all I need to do is superimpose them on the map (such as a 1:24,000 topographic map produced by a National Geographic map machine).
I wrote a quick program in Python and PostScript to produce templates in PDF format for various film formats and lens focal lengths, ready to print on a laser printer (I used Four Corners Paper IFR Vellum). I hope this will be useful. As an example, here is the template I use with my Fuji G617.