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

Readers' questions about any aspect of photography, or life ingeneral, 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 instrobe lighting equipment?

Wondering in Walnut Creek


DP: A watt is defined as a measurementof power equal to one joule per second. It was named after the Scottishengineer J. Watt (1736-1819). Watt was always coming up with bright ideasin response to the various technological needs of his time. When presentedwith a particular problem, he was often known to respond "Well, letme think upon that for a second..." His lab assistants made the remarkablediscovery that Watt spent a longer time deriving some solutions than othersand that the time he spent was relative to the amount of his intellect and"brightness" that was required. Thus, they came up with a measurementcalled the Watt-second which they used for determining the winner of theoffice betting pools on how long it would take Watt to find solutions tonew problems, such as matching the color of his socks each morning.

Later, when Doc (Papa Flash) Edgerton was developing the strobe lightat MIT, he needed a system to measure the power requirements and brightnesslevels of his new device. He adopted the watt-second as his measurementafter excitedly bringing his invention home to show his wife for the firsttime, only to have her respond with "Watt was that, dear?" (Itshould be noted that Edgerton had previously solved the problem of matchinghis socks in the morning by working through the night and going home tobed in the morning. Thus, the problem of matching socks became an afternoonconcern and of little further consequence.)

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

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©1991 Scott Highton
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