My Canon EOS 450D is not recognised as mass storage by my system when connected via USB. In order to get photos from camera to PC, you can use gphoto2:

#!/bin/bash
echo -n "[pullphotos] Detecting camera ...";
gphoto2 --auto-detect > /dev/null;
sleep 1s;
echo " Done";

echo -n "[pullphotos] Pulling photos ...";
gphoto2 -P &> /dev/null;
sleep 1s;
echo " Done";

echo -n "[pullphotos] Rotating photos ...";
jhead -autorot * &> /dev/null;
echo " Done";

This script copies all images currently stored on the camera into the current folder and rotates them if necessary¹. The necessary programs gphoto2 and jhead are available as packages with the same name from the Ubuntu repositories. Note that you have to empty your camera’s storage manually afterwards.

Furthermore, note that gphoto2 is a very powerful tool. It allows you to configure and control many aspects of your camera via USB, including remote capture—something you might want to employ?