18% Grey card

For my first short-film that I made for assignment one I wasn’t disciplined enough to carefully white-balance every shot; so my first film does I feel have some issues with consistent white-balance.  So I starting with assignment 2, every shot made in a different location, light or just different day, I always take a new white-balance measurement on my camera using a small grey-card in my X-Rite color-passport that I use for still photography.  This means that I can control the white-balance accurately and even make manual adjustments from a known starting-point should I want to warm or cool the image I am making.

This is important because I discovered that I can not correct my white-balance after taking the movie shot as I can with my still photography.

Since I first wrote this short blog I have read a book by John P. Schaefer, ‘The Ansel Adams Guide Book 1, Basic Techniques of Photography’ which offers additional useful uses for the 18% grey card. A grey-card can be used to calculate the correct exposure of a scene by using the Zone-system that Ansel Adams developed back in the 1930’s. Taking a spot-reading of the grey-card in the lighting conditions of the scene and barring in mind the light-meter is offering a reading for mid-grey which is zone V on Adams’ scale the correct exposure can be calculated allowing for shadows and highlights by either stopping up or stopping down from the averaged measurement taken off the light-meter. An understanding of the zone-system is required but is simple to learn.
zone 0 is black zone X is pure-white, zone II to zone VIII are regarded as textual zones ie within a range that can produce practicle visible texture. Each zone represents one stop either above or below zone V which is the averaged reading that your light-meter provides you with. This averaged reading reading would want to turn snow grey and a pile of coal grey.

Another use for a grey-card is for pre-exposures, not much use for film-making but good for still photography providing you are using a film camera or a digital camera that allows double exposures, my D-800e does; so i will try this out for extreme dynamic-range challenges in the field for landscape style images.


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