We can use the +/- to increase or decrease exposure. This is the feature called Exposure Compensation. Unfortunately, this feature does not work with flash. When the internal flash is used, rather than increasing or decreasing exposure, we need to increase or decrease the flash power, and this is what variable power means. Keep in mind that this capability is only available when the camera is in M-REC.
Why is this variable power (of flash) necessary? This is similar to exposure compensation. Under certain situations, we want to increase the exposure. Since exposure compensation does not work with flashes, to increase (resp., decrease) exposure is equivalent to increase (resp., decrease) the power of the flash under the same aperture and shutter speed. Therefore, this is the way of using variable power.
To activate variable power, follow the procedure below:
This VARIABLE POWER menu provides a list of flash power compensation values with a step size of 0.3 stop. The maximum and minimum are +2.0 stop and -2.0 stop, respectively. You can use the up arrow and right arrow of the multi-selector to scan this list. Once the desired compensation value appears, press the right arrow of the multi-selector to select it. In the following, the left (resp., right) image shows that the compensation of +0.7 stop (resp., -0.3 stop) is highlighted.
Note that once this option is chosen, it will stay even after the camera is turned off. Therefore, you need to go through the above procedure again to reverse the setting..
The following images show the same scene with different flash power output. From left to right, the flash output power is set to -2 stop, -1 stop, 0 stop, +1 stop and +2 stop. The images were shot with the aperture-priority mode with shutter speed 1/125 sec (the flash synchronization shutter speed) and F8.3. The impact of flash output power on the image is obvious. Thus, the variable power feature can serve as a way of performing exposure compensation when the internal flash is used.
|-2.0 stop||-1.0 stop||0 stop|
|+1.0 stop||+2.0 stop|
|Click on the image to see a larger one|