Tuesday, November 29, 2011

Old School Tuesday: The Zone System

I was listening to the Pro Photo Show Podcast with Gavin Seim talking about Light and Zones, and it brought back a lot of memories.  I swear I could smell the ammonium thiosulfate as he described why we still need to know and use the Zone System in the digital world today.  Give the show a listen, there's some pretty good stuff, then head over to his web page f164.com and check out his journal.  Some more info on the Zone System and other tidbits there.

For those that are new to photography, or have never heard of the zone system, it was developed by Ansel Adams and Fred Archer to determine optimal exposure and development of film.  In a nutshell, you break a scene down into a gradient of 11 stops going from pure black to pure white and expose for what you want the viewer to focus on:

0Pure black
INear black, with slight tonality but no texture
IITextured black; the darkest part of the image in which slight detail is recorded
IIIAverage dark materials and low values showing adequate texture
IVAverage dark foliage, dark stone, or landscape shadows
VMiddle gray: clear north sky; dark skin, average weathered wood
VIAverage Caucasian skin; light stone; shadows on snow in sunlit landscapes
VIIVery light skin; shadows in snow with acute side lighting
VIIILightest tone with texture: textured snow
IXSlight tone without texture; glaring snow
XPure white: light sources and specular reflections

Since you can't always expose for the entire scene, you need to set the camera so that the zone that is most important, say a subjects face, is exposed properly.  But that is where many photographers stop.  Using lights and reflectors you can often get each zone properly exposed in camera.  This area a stop brighter, that area two stops darker.  If the scene is too big to light artificially or too complicated, using a tool like Photoshop can allow you to raise or lower a zone in a scene a stop or two to correct the exposure on the zones.  If you're Joe McNally you just keep adding SB900's... A better way to do this is to bracket your shot, so each zone is properly exposed spanning several frames, then bring them all together in post.  This is the basis of High Dynamic Range images, or HDR.  Many think of HDR Photography as a new method, but it's essentially just a new twist on what Ansel Adams was doing back in the day.  I'll leave a couple links for some books that might help master the subject, they'll take you to Amazon so you can check out some reviews and take a "look inside" as they say, if available.  I highly recommend you check out your friendly neighborhood library to see if they can be checked out there first.  That's my first stop to learn about photography!