Nikon autofocus speedlight SB-900 User Manual page 56

Auto aperture flash
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Monitor pre-fl ashes
• Monitor pre-flashes on or off can be set by using the custom setting. (kC-22)
• The SB-900 fires a series of imperceptible monitor pre-flashes immediately
before the flash fires to obtain information on the subject.
• To perform the Auto FP-High Speed Sync (kD-55) or FV Lock (kD-55),
activate the monitor pre-flashes.
Flash shooting distance range in Auto aperture flash mode
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Notes on using a telephoto lens in the Auto aperture fl ash mode
• When shooting a distant subject using a telephoto lens in "Auto
aperture flash" mode, underexposure may occur even though the
subject is within the flash shooting distance range.
• Use of the i-TTL mode is recommended.
D–6
The flash shooting distance range is indicated by
numbers and a bar chart in the LCD.
• Set the shooting distance within this range.
• The range varies depending on ISO sensitivity,
camera's image area setting, illumination pattern,
angle of coverage and aperture. For more
information, see "Specifications." (kF-16)