Nikon R1 Instruction Manual page 73

 If the red ready-light blinks immediately after shooting
 In the M (manual) mode, set the manual flash output level for
Groups A and B.
In the TTL mode, when the SB-R200 flash has fired at its
maximum output and underexposure may have occurred, the
red ready-light on the SB-R200 blinks for approx. 3 sec. (The
ready-lights on the SU-800 and in the camera's viewfinder do
not blink.)
To compensate, set a higher ISO sensitivity or use a wider
aperture and reshoot.
Press the [SEL](FUNC.) button to display the manual flash
output level (blinking). Press the [] or [] button to increase
or decrease the value. Press the [SEL](FUNC.) button once
again and the manual flash output level stops blinking. The last
value to blink is the one that has been set automatically.
• Manual flash output level can be set separately for each
group.
• Manual flash output level can be set in 1 step increment or
decrement from M1/1 to M1/64 output level (M1/8 is preset
when shipped from the factory).
• Pressing the [] or [] button continuously increases or
decreases the value quickly.
• Manual flash output level blinks during adjustment and stops
after blinking six times unless an adjustment is made. The
last value to blink is the one that has been set automatically.
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