Recently, I've returned back to school to brush up on some the digital photography techniques I may have missed and get up to date on the newest and latest in the field. To my surprise, I learned the most basic and oldest rules of metering. Somehow missed a long time ago.
Basic Exposure Constant, otherwise known as BEC, is a set of rules for metering that has been around since the earlier days of photography when cameras didn't have built in light meters and photographers didn't have hand held ones for that matter. The BEC is a system that determines the correct exposure of the image with out using a light meter.
So how does it work? .
Let's start out with the F16 rule:
"On a sunny, bright day defined by sharp distinct shadows, the exposure will be F/16 @ the reciprocal of the ISO."
Next here is the Aperture chart:
F/22 Super sunny bright/reflective light-medium shadows, hard edges
F/16 Sunny bright,-dark shadows, hard edges
F/11 Partially cloudy-medium shadows, soft edges
F/8 Overcast bright light-no shadows
F/5.6 Overcast dull/blue sky-no shadows
F/4 Dark/no sky-no shadows
F/2.8 One hour before sunset-no shadows
So what does all this mean?
This is how I've come to understand it. It means your Aperture/ f-stop will be determined by the lighting conditions in which you are shooting (Aperture chart). The ISO speed will also be determined by the lighting conditions, thus giving you a shutter speed of 1/ISO.
Example: When taking a photo of people on the ski slopes on a bright sunny day the settings will be: F/22-ISO 100-Shutter speed 1/100.
If your light meter stops working you now know how to properly expose an image using BEC. Thought I'd pass along this little nugget of wisdom. Keep on learning!
