Nikon SB-26 Instruction Manual - Page 52

11 Confirm subject is at the distance shown by the indicator bar / in the SB-26's LCD panel (from step 10). To determine the subject-to-camera distance, read the distance scale on the lens barrel. If the bar location matches the subject-to-camera distance from steps 10 and 11, the subject will be correctly exposed with the selected aperture, shutter speed, and light output amount. If the subject-to-camera distance does not match the appropriate shooting distance, readjust the indicator bars by: a. Pressing ı button to switch from FP1 (F with 1) to FP2, or vice versa. The bar / location then moves to show an alternate shooting distance. b. Moving closer to or further from the subject. c. Choose a different number for the zoom-head posi- tion (altering guide number). 12 Look into camera's viewfinder again, then compose and lightly press the shutter release button to check that the ready-light is on in the camera's viewfinder g. Ready-light also appears on the SB-26 Â. 13 Fully depress shutter release button to fire flash. Guide number in FP High-Speed Sync Flash The "guide number" helps you determine an exact flash- shooting (flash-to-subject) distance for the selected aper- ture (f/stop number). FP guide numbers vary with the ISO film speed in use, shutter speed and zoom-head position. Use the equation below for your calculations, and check the following chart for guide numbers. This same equation can be applied to determine an appropriate aperture once the distance is known. [flash-shooting distance] = [guide number] [f/stop] For example, in FP1 operation with an aperture of f/4, a shutter speed of 1/500 sec., a zoom-head position of 35mm and a film speed of ISO 100, the chart recommends a guide number of 12 (or 39 for feet): If measuring in meters; [flash-shooting distance] = 12 4 = 3 if measuring in feet; [flash-shooting distance] = 39 4 = 9.75 Next, adjust subject and flash/camera location for 3 meters, or 9.75 feet, to obtain correct exposure in FP1 flash opera- tion. Chapter 4 FP High-Speed Sync Flash FP1 guide number (at ISO 100; for meters/feet) Shutter speed 1/250 1/500 1/1000 1/2000 1/4000 24mm 14/46 10/33 7/23 5/16 3.5/11 Zoom-head position 28mm 35mm 50mm 70mm 15/50 17/56 20/65 23/74 11/36 12/39 14/46 16/52 7.5/25 8.5/28 10/33 11/36 5.3/17 6/20 7/23 8/26 3.7/12 4.2/14 5/16 5.6/18 85mm 24/77 17/56 12/39 8.5/28 6/20 FP2 guide number (at ISO 100; for meters/feet) Shutter speed 1/250 1/500 1/1000 1/2000 1/4000 24mm 10/33 7/23 5/16 3.5/11 2.5/8.2 Zoom-head position 28mm 35mm 50mm 70mm 11/36 12/39 14/46 16/52 7.5/25 8.5/28 10/33 11/36 5.3/17 6/20 7/23 8/26 3.7/12 4.2/14 5/16 5.6/18 2.6/8.5 3/10 3.5/11 4/13 85mm 17/56 12/39 8.5/28 6/20 4.2/14 Using a film speed other than ISO 100 For film speeds other than ISO 100, multiply the above fig- ures by the factors shown in the following chart. If the film speed in the previous example had been ISO 400 rather than ISO 100: [flash-shooting distance] = 12 4 x 2 = 3 x 2 = 6 if measuring in feet; [flash-shooting distance] = 39 4 x 2 = 9.75 x 2 =19.5 You should have obtained 6 meters, or 19.5 feet, for correct exposure. Adjustment factors for other ISO film speeds ISO film speed 25 50 100 200 400 800 1600 Factor x 0.5 x 0.7 x 1 x 1.4 x 2 x 2.8 x 4 102 103