Nikon R1 Instruction Manual page 119

Auto Aperture (AA) flash mode
The SU-800's built-in sensor measures the flash illumination reflected from the
subject and controls the flash output in combination with data automatically
transmitted from the camera and lens to the SU-800, including the ISO sensitivity
value and exposure compensation value as well as the aperture and focal length
of the lens.
• Auto Aperture flash is available only when the SB-800 is used as a remote flash unit. (A
warning indicator appears if the SB-R200 or SB-600 receives an Auto Aperture (AA) flash
mode signal.)
• If the flash mode is set to Auto Aperture flash while a non-CPU lens is mounted, the AA
mode display blinks as a warning, and the flash units will not fire.
• For flash shooting distance range in the Auto Aperture flash mode, read the instruction
manual of your Speedlight.
 Notes on performing flash operation in the Auto Aperture flash mode
When taking a distant subject, underexposure may occur even though the
subject is within the flash shooting distance range. Use of the TTL auto mode is
recommended with cameras compatible with TTL auto flash.
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