Nikon Speedlight SB-700 User Manual

Also see for Speedlight SB-700: Manual Quick guide

Contents

Nikon Speedlight SB-700 User Manual Manual pdf 135 page image

H–6Tips on Speedlight Care and Reference InformationHGuide Number, Aperture and Flash-to-subject DistanceThe guide number (GN) indicates the amount of light generated by a ash unit. As the number increases, the ash output becomes greaterand the light extends further.There is a relation represented by an equation, guide number (m orft.; for ISO 100) = ash-to-subject distance (m or ft.) × f-number ofaperture. The SB-700’s guide number is 28 m (92 ft.) (for ISO 100,zoom head position: 35 mm, FX format, illumination pattern: standard,temperature: 20 C/68 F). When ISO sensitivity is 100 and f-numberof aperture is 8, the illumination of the SB-700 reaches 3.5 m (11 ft.),which is determined by the equation, ash-to-subject distance (3.5 mor 11 ft.) = guide number (28 m or 92 ft.) / f-number of aperture (8).For ISO sensitivities other than 100, multiply the guide number by•the factors (ISO sensitivity factors) shown in the table below.ISO 25 50 100 200 400 800 1600 3200 6400Factor 0.5 0.71 1 1.4 2 2.8 4 5.6 8See “Specifications” for more details. (• 0H-21)t Determining aperture and ash-to-subject distance forcorrect exposuref-number of aperture =guide number (GN for ISO 100; m or ft.) ×ISO sensitivity factor / ash-to-subject distance (m or ft.)Flash-to-subject distance (m or ft.) =guide number (GN for ISO 100; m or ft.) ×ISO sensitivity factor / f-number of aperture