Canon EOS 5Ds Instruction Manual page 474

Troubleshooting Guide
I have to press the shutter button twice completely
to take a picture.
If [z4: Mirror lockup] is set to [Press V twice to shoot], set it to
[Disable].
The image is out of focus or blurred.
Set the lens's focus mode switch to <AF> (p.52).
Press the shutter button gently to prevent camera shake (p.54-55).
If the lens has an Image Stabilizer, set the IS switch to <1>.
In low light, the shutter speed may become slow. Use a faster shutter
speed (p.206), set a higher ISO speed (p.158), use flash (p.244), or
use a tripod.
See "Minimizing Blurred Photos" on page 235.
There are fewer AF points.
Depending on the attached lens, the number of usable AF points and
patterns will differ. The lenses are categorized into nine groups from A
to I. Check which group your lens belongs to. Using a lens in Groups F
to H will have fewer usable AF points (p.103-104).
The AF point is blinking or two AF points are displayed.
Regarding lighting up or blinking of the AF points when you press the
<S> button, see page 94.
The AF point at the registered area is blinking (p.94, 418).
The manually-selected AF point (or zone) and the registered AF point
are displayed (p.93, 418).
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