One of the benefits of working with a dedicated speedlight flash unit is that it opens up a whole world of excellent automatic flash exposure possibilities. In many cases, smart flashes are designed to provide the speed and ease of automatic exposures with the accuracy and control of manually adjusted flash outputs.
Still, sometimes smart flashes get fooled. That’s why so many photographers insist on manual control of their flashes at all times. But those photographers might be missing out. There is a third way, a happy medium between an “all auto, take what it gives you” approach, and one that requires deliberate intervention with the camera and strobe controls on every exposure. This approach relies on using TTL automatic exposure settings, as well as the features of a given flash that provide even more control over the flash’s automatic output. That’s what we’re going to look at with this post, and over the next few weeks. What are the tools that provide the Type A among us with the control we want, while still providing the many benefits of an automatic flash output?
Today we’re going to look at a really straightforward but still totally useful automatic flash control: flash exposure compensation.
Expressed by a lightning bolt with a +/- next to it, the flash exposure compensation control is pretty simple to use. Just like the exposure compensation on a camera, flash exposure compensation tells the automatic metering system that you’d like more or less light, depending on the setting. Continually finding the flash underexposing a high-key scene? Increase the exposure compensation to a stop or more. Do you find that the fill flash is looking too strong in bright daylight? Try using the flash exposure compensation to tell the flash you’d like to see less light.
To control flash exposure compensation, look for the lightning bolt icon with the +/- next to it on the back of the flash. On the new Nikon SB-5000, it’s at the top of the rotary selector found below the LCD. Simply click it to activate flash exposure compensation, and then dial in the value plus or minus from the “correct” exposure. On a Canon 600EX-RT, the +/- icon near the bottom of the LCD corresponds to the button just below it. In Manual mode, this button adjusts the overall output of the flash. But in ETTL mode, this button controls the Flash Exposure Compensation to as much as three stops over or under the “correct” exposure.
If you’re in a particularly tricky lighting situation, or you just want to make sure your bases are well covered, consider using flash exposure compensation via Flash Exposure Bracketing. Found on all top-of-the-line flashes, flash exposure bracketing allows you to dial in the flash exposure compensation for each of three frames, so that you can take three pictures in succession, each with a different amount of flash exposure compensation, and determine which amount of exposure compensation is appropriate going forward.
To access this feature on a Canon 600EX-RT, look for the third button just below the LCD on the back. Notice the LCD reads FEB just above the button on the screen? Pressing it will activate the flash exposure bracketing icon on the screen. Then, using the select dial, rotate to set the flash exposure compensation to be applied to each of the three separate exposures. In third-stop increments, this can be anywhere from one-third of a stop to a full three stops over- and under-exposed. The flash exposure bracketing icon then disappears, and the flash is returned to its normal shooting mode—unless you set a custom function to turn off auto cancellation of the FEB function after three shots. This is a great technique for determining appropriate flash fill, especially when working in bright daylight when it can be difficult to see the results on the LCD screen.
Speaking of bright daylight, did you know that really smart flashes use their TTL evaluative metering to determine that you’re shooting in broad daylight, and so you’re likely to be using the flash as a fill, thereby automatically reducing the flash’s output accordingly? That’s a seriously smart flash. And it’s indicative of how the devices of today have been designed to provide every mechanical advantage possible to photographers who shoot in fast-paced, changing environments where automatic flash control is helpful. Stay tuned for more improvements to TTL automatic flash next week.