Canon EOS 20D Digital, Service Manual

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5) White balance
(1) Auto white balance
The auto white balance has been improved from that of the EOS 10D and
EOS DIGITAL REBEL/EOS 300D DIGITAL to make color reproduction more
accurate and natural. Moreover, with DIGIC II and an improved algorithm,
the white balance is now more stable. Also, color reproduction (natural reds)
under low color temperatures such as tungsten has been improved along
with improved skin tone reproduction.
The EOS 20D incorporates a new system that incorporates the flash's color
temperature information (when fired) in the image processing. When the
built-in flash or SL580EX is used and the white balance is set to "AWB" or
"Flash," the white balance will be more accurate for low-light shots.
(2) White balance correction
As with the EOS-1D Mark II, you can
correct the color temperature for the white
balance mode currently set. You can thereby
obtain the same effects as using a color
temperature conversion filter or color
correction filter. Each color can be corrected
up to nine levels in single-level increments.
The blue/amber bias and magenta/green
bias corrections (diagonal coordinates) can
also be set in combination.
On the CIE xy color graph, the correction
direction will be as shown in Fig. 009. The
preset white balance color temperature
(approx. 2800K - 10000K) is based on the
blackbody radial locus. The EOS 10D could not obtain the proper white
balance for types of lighting that had bad color rendition. But now, since the
magenta/green bias can also be corrected in addition to the blue/amber bias
(with WB-BKT), the camera can match various types of lighting.
With the EOS 20D, the WB correction and WB
bracketing can both be set together on the LCD
monitor. While looking at the point coordinates,
use the Multi-controller to move the point to the
desired coordinates. Then turn the Quick Control
Dial to set the bracketing. On the right of the
screen, "SHIFT" shows the correction information
and "BKT" shows the bracketing information.
Fig. 011 shows samples of WB correction.
Technical Information
7
White fluorescent light
Blackbody
radial locus
Tungsten
light bulb
Daylight
color graph
Fig. 009 WB correction conceptual diagram
Fig. 010 WB correction/BKT setting screen
None B: +5 levels A: +5 levels M: +5 levels G: +5 levels
Fig. 011 WB correction samples