Canon EOS 6D Instruction Manual page 157

w: HDR (High Dynamic Range) ShootingN
If you shoot a moving subject, the subject's movement will leave
afterimages.
To prevent camera shake, the ISO speed may be set higher than usual.
HDR shooting is not possible with ISO expansion. (HDR shooting is
possible within the range of ISO 100 - 25600.)
When shooting HDR images with [Auto Image Align] set to [Enable],
AF point display information (p.240) and Dust Delete data (p.281) will not
be appended to the image.
If [Auto Image Align] is set to [Enable] and the HDR picture is shot
handheld, the edges of the photos will be cropped, lowering the
resolution slightly. Also, if the images cannot be aligned properly due to
camera shake, etc., auto image alignment may not take effect. Note that
when shooting with excessively bright or dark exposure settings, auto
image alignment may not work properly.
If you perform handheld HDR shooting while [Auto Image Align] is set
to [Disable], the 3 images may not be properly aligned and the HDR
effect may be minimal. In such a case, using a tripod is recommended.
Auto image alignment may not work properly with repetitive patterns
(lattice, stripes, etc.) or flat, single-tone images.
The color gradation of the sky or white walls may not be reproduced
correctly. Irregular colors or noise may appear.
HDR shooting under fluorescent or LED lighting may result in unnatural
color reproduction of the illuminated areas.
Since HDR shooting merges the images, it will take a longer time to
record the HDR image to the card than with normal shooting. During the
processing of the images, "buSY" will be displayed in the viewfinder and
on the LCD panel and you cannot take another picture until the
processing is completed.
In HDR mode, the options grayed out in the camera menu cannot be set.
Note that when you set HDR mode, the Auto Lighting Optimizer, highlight
tone priority, and exposure simulation will be set to [Disable] before
shooting.
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