Canon EOS-1D C Instruction Manual page 378

Troubleshooting Guide
No images can be shot or recorded.
Make sure the card is properly inserted (p.35).
If the card is full, replace the card or delete unnecessary images to
make room (p.35, 284).
If you try to focus in the One-Shot AF mode while the focus
confirmation light <o> in the viewfinder blinks, a picture cannot be
taken. Press the shutter button halfway again to refocus automatically,
or focus manually (p.46, 111).
The card cannot be used.
If a card error message is displayed, see page 37 or 392.
An error message is displayed when the card is inserted in
another camera.
Cards with capacities greater than 128 GB are formatted in exFAT.
This means that if you format a card with a capacity over 128 GB with
this camera and then insert it into another camera, an error may be
displayed and it may not be possible to use the card.
The image is out of focus.
Set the lens focus mode switch to <AF> (p.43).
To prevent camera shake, press the shutter button gently (p.45, 46).
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.171), set a higher ISO speed (p.128), use flash (p.193), or
use a tripod.
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