Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 307)

General Movie Recording Precautions
Caution
Red < > internal temperature warning icon
If the camera's internal temperature increases due to prolonged movie recording or
under a high ambient temperature, a red <
> icon will appear.
The red < > icon indicates that movie recording will soon be terminated
automatically. If this happens, you will not be able to shoot again until the camera's
internal temperature decreases, so turn off the power and let the camera cool down
a while. Note that the time until movie recording stops automatically when the red
<
> icon is displayed varies depending on shooting conditions.
Recording a movie at a high temperature for a prolonged period will cause the red
<
> icon to appear earlier. When you are not recording, always turn off the
camera.
Recording and image quality
If the attached lens has an Image Stabilizer and you set the Image Stabilizer switch
to <
>, the Image Stabilizer will operate at all times even if you do not press the
shutter button halfway. This will consume battery power, and it may reduce the total
movie recording time. When the Image Stabilizer is not necessary, such as when
using a tripod, it is recommended that you set the Image Stabilizer switch to
<
>.
If the brightness changes as you record a movie with Program AE or shutter priority
AE, the movie may appear to stop momentarily. In this case, record movies with
manual exposure.
If there is a very bright light source in the image, the bright area may appear black
on the screen. Movies are recorded almost exactly as they appear on the screen.
Image noise or irregular colors may occur when shooting at high ISO speeds, high
temperatures, slow shutter speeds, or under low light. Movies are recorded
essentially as they appear on the screen, except with Canon Log View Assist.
Video and audio quality of recorded movies may be worse on other devices, and
playback may not be possible, even if the devices support the camera's recording
formats.
If you use a card with a slow writing speed, an indicator may appear on the right
of the screen during movie recording. The indicator shows how much data has
not yet been written to the card (remaining capacity of the internal buffer
memory), and it increases more quickly the slower the card is. If the indicator (1)
becomes full, movie recording will stop automatically.
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