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E-TTL II: Smarter Flash Performance
Canon's high-end Digital SLRs employ E-TTL II, the most advanced flash metering technology,
to solve problems encountered by photographers. Occasionally, if you lock focus and
recompose your shot, this could result in a non-optimal exposure with previous systems.
E-TTL II remedies this by ignoring the active focusing point, considering distance information
and evaluating pre-flash information immediately before the exposure occurs. Sometimes
in flash photography, mirror-like objects in the image cause the sensor to register localised,
abnormally high levels, and would result in underexposure. E-TTL II knows to ignore
those levels, resulting in the correct exposure. This feature is useful when shooting
a subject with a highly reflective object in the background, or if the subject itself
is highly reflective. Metered areas with large discrepancies between ambient and
pre-flash readings are excluded or down-weighted because they are assumed to
contain a highly reflective subject. These readings are weighted, averaged and
compared with the ambient light reading and the main flash output is then set and
stored in memory, ensuring consistent flash output through a number of shots.
Speedlite 580EX
Approx. 25% faster recycling time compared to previous 550EX.
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Superior evenness of exposure, centre to corner of frame.
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Slightly higher max. guide number at 105mm setting (GN 58–meters at ISO 100).
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Auto conversion of flash coverage with compatible Digital SLRs.
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White Balance info communicated instantly to compatible Digital SLRs.
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Full swivel, 180° in either direction (first TTL flash with this ability).
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AF-assist beam now compatible with all AF points on every EOS SLR.
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Select Dial for easy inputs and user control.
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Speedlite 430EX
Significantly greater user control via new LCD panel on rear of flash.
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Wide-angle pull-down panel covers 14mm lens (on a full-frame camera).
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Slightly higher max. guide number at 105mm setting (GN 43–meters at ISO 100).
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Auto conversion of flash zoom coverage with compatible Digital SLRs.
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White Balance info communicated instantly to compatible Digital SLRs.
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Bounce upward to 90°; swivel right (to 90°) and left (180°).
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