Editor's note: the following is a tongue-in-cheek, often irreverent, question and answer column published in the ASMP News solely for the entertainment of our readers. It does not necessarily reflect the views of ASMP, the local chapter or other ASMP members. All opinions and answers are solely those of the author, and he is welcome to them.

Readers' questions about any aspect of photography, or life in general, are welcome and Dr. Photography will answer them in future columns, if he happens to feel like it. Send mail to:
Dear Dr. Photography

Dear Dr. Photography,

What is a watt-second and how is it used in strobe lighting equipment?

Wondering in Walnut Creek


DP: A watt is defined as a measurement of power equal to one joule per second. It was named after the Scottish engineer J. Watt (1736-1819). Watt was always coming up with bright ideas in response to the various technological needs of his time. When presented with a particular problem, he was often known to respond "Well, let me think upon that for a second..." His lab assistants made the remarkable discovery that Watt spent a longer time deriving some solutions than others and that the time he spent was relative to the amount of his intellect and "brightness" that was required. Thus, they came up with a measurement called the Watt-second which they used for determining the winner of the office betting pools on how long it would take Watt to find solutions to new problems, such as matching the color of his socks each morning.

Later, when Doc (Papa Flash) Edgerton was developing the strobe light at MIT, he needed a system to measure the power requirements and brightness levels of his new device. He adopted the watt-second as his measurement after excitedly bringing his invention home to show his wife for the first time, only to have her respond with "Watt was that, dear?" (It should be noted that Edgerton had previously solved the problem of matching his socks in the morning by working through the night and going home to bed in the morning. Thus, the problem of matching socks became an afternoon concern and of little further consequence.)

Photographers today continue to use the term to impress clients with the size and power of equipment in their studios, which allows them a greater latitude in their fees charged. Since most clients really don't care about such technical things, they are often happy to pay a higher price just to get the photographer to shut up.

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©1991 Scott Highton
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