This handy tool gives you instant calculations of shooting range, aperture and guide numbers for manual flash settings.
The guide number for an electronic flash measures its ability to illuminate the subject to be Some flash units have a dial on the back (in fact, a simple circular slide rule) or a chart to help in calculating the desired settings. The aperture given.
FLASH GUIDE NUMBERS. COVER. An Extension to. The Textbook of Digital Photography. Flash. Guide Numbers. D ENNIS P. C.