SIGMA DP3 Merrill - Manual (Page 44)

43
SHUTTER BUTTON
The shutter button of the DP3 Merrill cameras has two positions. When
you press the shutter button “halfway down”, the camera’s autofocus
systems will activate. When pressing the button “all-the-way down”, the
shutter will release to take a picture.
TIP

Before you start to take pictures, we recommend that you operate
the camera, to become familiar with the “halfway down” position
and other features of the camera.

Normally, if the card is not inserted in to the camera body, it is not
possible to release the shutter. If you would like to release the shutter
without a card, please set from [
Camera Settings] (P.28) →
[Release without Card].
Disable
(Default)
When the card is not inserted in the camera body, it
is not possible to release the shutter.
Enable
It is possible to release the shutter, even if the card
is not inserted in the camera body.