guide number
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guide number
[′gīd ‚nəm·bər] (graphic arts)
A number that relates the output of a light source (such as a flashbulb) to the sensitivity of a particular film; when the number is divided by the distance in feet to the subject, it gives the T stop at which the lens should be set.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive
I've stood for awestruck moments on the eastern slope of Table Mountain, a flattened pile of windfaceted sandstone so enormous it seemed to thrum; then
guide number one whisked me away.
With a
guide number of 112 feet at ISO 100 the SB-910's power will blind you silly.
The anticipated cable television reference
guide number has not been officially released.
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