Bolt VS-570SMI Wireless TTL Flash for Cameras - Manual (Page 19)

Using Flash Exposure Compensation | 19
Using Flash Exposure Compensation
In automatic TTL mode, you can use flash exposure compensation to adjust the VS-570’s flash output
incrementally, just as you would adjust exposure with the exposure compensation function on your camera.
To apply flash exposure compensation, press the up or
down buttons on the flash to increase or decrease flash
exposure by 1/3 stop—up to 3 stops total. The LCD will
display EV+ or EV- next to the exposure value to indicate
whether it is increased or decreased.
H TTL
EV+