What's that gadget at photo shoots?

Jay is correct. When they hold it in front of the person, they are taking an incident reading. It measures the light falling on the subject. The meter in your camera takes a reflective reading which reads the light bouncing off your subject. In most cases the incident reading is more accurate since it's not fooled by different colors and shades.

Light meter. You tell it what ISO you're shooting at, and at what shutter speed, and it'll tell you what aperture to set your camera. Some also trigger the flash, to get the same measurements.

It tells you what settings to use for a properly exposed image.

Thanks Jay... I liked her better all jittery and nervous.

Now go buy one: http://www.google.com/products?hl=en&source=hp&q=Incident+meter&um=1&ie=UTF-8&ei=KIQ7S6CFDYnUlAfCjY2YBw&sa=X&oi=product_result_group&ct=title&resnum=4&ved=0CC0QrQQwAw
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