Using Variable Power: Flash Compensation

We can use the +/- to increase or decrease exposure. This is the feature called Exposure Compensation. Unfortunately, it does not apply to 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 feature is only available when the camera is in the program (P) mode, aperture-priority (A) mode, shutter-priority (S)mode, and manual-exposure (M) mode.

Why is this variable power (of flash) necessary? This is similar to exposure compensation. Under certain situations, we want to increase or decrease exposure. Since exposure compensation does not work with the flash, to increase (resp., decrease) exposure is equivalent to increase (resp., decrease) the output power of the flash under the same aperture and shutter speed. Therefore, this is the way of using variable power.

Activating Variable Power

To activate variable power, follow the procedure below:

• Set the camera to the P mode, A mode, S mode or M mode by holding the MODE button and turning the command dial at the same time.
• Press the MENU button once to enter the first page of the SHOOTING MENU. You will see the following screen:
  
• Use the down arrow of the multi-selector to enter the menu system. The first menu item is highlighted as shown in the left image below. Then, press the MENU button twice to enter the third page as shown in the right image below.

• Use the down arrow of the multi-selector to highlight the Speedlight Opt. option as shown in the left image below. Then, use the right arrow to select this option. The SPEEDLIGHT OPT. menu appears as in the right below.

• Use the down arrow of the multi-selector to highlight the Variable Power option as shown in the left image below. Then, use the right arrow to select this option. A list of selections appears in the lower-right corner of the monitor as shown in the right below.

• This list consists of flash power compensation values from -2.0 stop to +2.0 stop with an increment of 0.3 stop. You can use the up arrow and right arrow of the multi-selector to scan this list. Once the desired compensation value appears, use the right arrow of the multi-selector to select it. The left screen shot below shows the -1.0 stop option is highlighted.

  Suppose we wish to use +0.7 stop. We should highlight +07.stop and press the multi-selector to make a selection. Then, press the MENU button to return to the shooting mode. Note that this the monitor does not show this variable power setting. However, when you enter the SPEEDLIGHT OPT. menu next time, you will set the variable power setting that is currently in effect.

  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..

Examples

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.