Sony ILCA-99M2 Manual page 291

The flash works in dark environments or when shooting towards bright light.
Fill-flash:
The flash works every time you trigger the shutter.
Slow Sync.:
The flash works every time you trigger the shutter. Slow sync shooting allows you to shoot a
clear image of both the subject and the background by slowing the shutter speed.
Rear Sync.:
The flash works right before the exposure is completed every time you trigger the shutter. Rear
sync shooting allows you to shoot a natural image of the trail of a moving subject such as a
moving car or a walking person.
Wireless:
Allows you to shoot by removing the external flash (sold separately) and using it at a distance
from the camera.
The shading effect gives the subject a more three-dimensional feel.
Note
The default setting depends on the shooting mode.
Some [Flash Mode] settings are not available, depending on the shooting mode.
[307] List of MENU items
Flash Comp.
Adjusts the amount of flash light in a range of –3.0 EV to +3.0 EV. Flash compensation changes
the amount of flash light only. Exposure compensation changes the amount of flash light along
with the change of the shutter speed and aperture.
MENU →
1
Selecting higher values (+ side) makes the flash level higher, and lower values (- side)
makes the flash level lower.
Note
[Flash Comp.] does not work when the shooting mode is set to the following modes:
[Intelligent Auto]
[Sweep Panorama]
The higher flash effect (+ side) may not be visible due to the limited amount of flash light available, if
the subject is outside the maximum range of the flash. If the subject is very close, the lower flash
Camera Settings1
(Camera Settings1) → [Flash Comp.] → desired setting.