The Canon EOS Digital Rebel XSi/450D Companion

FLASH SHOOTING

USING THE XSI’S ONCAMERA FLASH

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Using the XSi’s On-Camera Flash

In Chapter 7, you saw how you can use the on-camera flash to even out an ex-

posure by brightening a dark subject when your background is too bright. You’ve

also seen how you can use fill flash to even out darker shadows in a scene.

But there will be times when you’re in a dimly lit room and simply need some

extra light. In these snapshot-type situations, the XSi’s on-board flash can do a

good job of illuminating your scene, but you might need to take a little more

control to get a good shot.

Flash Exposure

When you half-press the shutter button while the flash is popped up, the XSi

calculates an exposure, just as it does when the flash is down. However, with the

flash up, it bases its exposure on its understanding of how much light the flash

will be able to add to the scene. e camera will never pick a shutter speed slower

than 60 to ensure handheld shooting. It will also never pick a shutter speed faster

than 200, because it’s not possible for the entire sensor to be exposed to the flash

if the shutter speed exceeds 200.

When you take a shot after metering, the camera will turn the flash on. When it

sees that enough light has been added to the scene to properly expose it at the

current settings, it then turns the flash off. In other words, while it might appear

that the flash is always just a quick flash of ...