Sony ILCE-7S - Manual (Page 69)

Assigns zoom in (T) function to left-handed rotation and zoom-out (W) function to right-
handed rotation.
Note
This function is available only with a power zoom lens whose operation direction is
variable.
[50] How to Use Using shooting functions Using the flash
Using flash (sold separately)
In dark environments, use the flash to light up the subject while shooting and to prevent
camera-shake. When shooting against the sun, use the flash to lighten the image of the
backlit subject.
1. Attach the flash to the product (sold separately).
2. Press the shutter button fully down.
Note
You cannot use the flash when recording movies.
While charging the flash, flashes. After charging is completed, the flashing icon will
light up.
Do not use a commercially available flash with high-voltage synchro terminals or with
reverse polarity.