I'll describe here how to automatically capture images with Canon A75 using gphoto2 software.
After connecting camera first step is to enable capture mode:
gphoto2 --set-config /main/settings/capture=1
Next capture image and download it:
gphoto2 \ --set-config /main/capturesettings/shootingmode=Manual \ --set-config /main/capturesettings/shutterspeed=1/50 \ --set-config /main/capturesettings/aperture=4.5 \ --capture-image-and-download
To see list of available configuration settings execute:
gphoto2 --list-config
To see possible values of certain setting:
gphoto2 --get-config /main/capturesettings/shutterspeed
To use a GUI to set configuration:
gphoto2 --config