Definition of guide number in English:

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guide number


A measure of the power of a flashgun expressed in meters or feet.
Example sentences
  • Such technical items as ‘guide numbers’ don't seem to matter any more.
  • Unless you're shooting under those conditions, consider the guide numbers to be estimates.
  • Small flashes have guide numbers ranging from 45-80, while large shoe-mount units will be up to around 130.

For editors and proofreaders

Syllabification: guide num·ber

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