Samsung Galaxy NX500 Camera User Manual (en)

Shooting Functions > 
You can also drag the slider or touch 
 to adjust the intensity.
Adjusting the flash intensity may not be effective when:
The subject is too close to the camera.
You set a high ISO sensitivity.
The exposure value is too big or too small.
It is too bright or too dark.
In some shooting modes, you cannot use this function.
If you attach an intensity-adjustable external flash to the camera, the intensity 
settings of the flash will be applied.
If the subject is too close when you use the flash, some light may be blocked, 
resulting in a dark photo. Ensure that the subject is within the recommended 
range, which varies by lens.
When a lens hood is attached, the light from the flash can be blocked by the 
hood. Remove the hood to use the flash.
Flash settings
Set the flash mode, exposure value, flash brightness, or multi flash when 
you attach an external flash to the camera. You can also set wireless sync to 
control the external flash. The flash settings are supported only when you 
attach a compatible, optional external flash (SEF-580A).
Setting external flash
To set external flash,
In Shooting mode, press [m] 
 External Flash 
 an option.