57■ Calculating the Flash Effective RangeWhen setting the lens to manual f/stop, calculatethe guide number at main flash with the use offlash's zoom position and ISO. Divide the resultingguide number by the aperture in use. Thus, themaximum distance is obtained. The minimum dis-tance is obtained in dividing this max. distance byapprox. 10.However, if the minimum distance obtained is 0.7mor less, the minimum distance will be 0.7m. Referto page 59 for the guide number table.FLASH EFFECTIVE RANGE[Example] :With a 85 mm lens at f/4 and sensitivity at ISO100① For the zoom position 85mm and sensitivity at ISO100, the guide number is 54.② 54 (guide number) /4 (aperture) = 13.5m (max. distance)③ 13.5m (max. distance) /10 = 1.35m (min. distance) Thus, flash effective range is approx. 1.35m - 13.5m.