Get the right exposures for your photos.
Finalcombo: Abackground exposure 1 1/3 stops over thecamera's spotmeter reading maintained aslight backlight effect without blowingout highlights. Flash setting of -1 1/3EV illuminated subject without an obviousflash effect. Combinations in this rangelook most natural.Fillflash is a method of using flash—usually in backlitsituations—so that it doesn't look like flashat all, but a perfectly exposed, ambient-lightpicture. Using fill flash correctly means understandinga single basic principle: every flash shot isreally two exposures occuring simultaneously.Oneexposure is the ambient exposure. Lightnessor darkness is determined by a combination off-stops and shutter speeds. The other is theflash exposure. Lightness or darknessis determined by flash power and, if your flashis an auto unit, flash duration. You also canvary exposure by changing the distance of flashto subject, or your lens's f-stop. But shutterspeed has no effect on an electronic-flash exposure.
Manycameras today with built-in flash heads do thisbalancing act automatically; you need only setthe camera to fill flash (or pop up the flashhead) and snap away. But for full control overfine-tuning fill flash, you need a dedicatedTTL flash/camera system, or at least a built-inflash allowing flash exposure compensation.Here's how to do it.
1)Set the ambient exposure first; this is thegeneral exposure for the background—sunset,skyline, garden trees, etc. Whatever cameramode you use, make sure the shutter speed selectedis at or below the fastest flash-sync speedyour camera allows.
2)Determine how much fill you want. Usually youdon't want a full flash exposure (unless youwant it to look exactly like a flash shot),but one half, one third, or one quarter of fullexposure. For half intensity, dial in -1 EVof flash compensation; for one-third fill, -11/3 or -1.5 EV; for one quarter, -2 EV.
3) Shoot!
1) Set the camera to a general exposure for thebackground, as above.
2) Fool your flash unit into thinking you're usinga faster film. The easiest way is to reset thefilm speed dial on the flash: For half flash power,set the flash ISO to double the actual film speed.(For example, if you're shooting 100-speed film,set the flash dial to ISO 200.) For one-thirdflash power, set the flash to 2.5X the actualfilm speed. For one-quarter flash power, set theflash to four times the actual film speed.
3) Shoot!
Youmay have to fiddle with your exposure settingsin this case. Many non-TTL flashes have a limitednumber of autoflash settings available—threeapertures is quite common—so you may have toshift your ambient exposure by means of theshutter speed.
Noteon flash-sync speeds: SLR focal-plane shutterscan synchronize with electronic flash only upto a certain speed. Most newer cameras can syncto at least 1/125 sec; high-end AF cameras oftensync to 1/250 sec. Check your manual foryour camera's top sync speed. If you gofaster than maximum sync speed, you'll get justa band of flash or no flash at all in the picture.
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