You have to find out which device it is mapped to: USB mass storage devices work like emulated SCSI disks, so e.g., if you don't already have SCSI hard drives in your system, it will likely be mapped to /dev/sda (=the first scsi hard disk) because .
Then depending on the model of your camera the data may be on partition 1,2,3, or 4. I have a USB memory stick that maps to /dev/sda1, and another one that maps to /dev/sda4. No way of really telling that in advance...
Just try to mount all possible combinations: as root, do mount -t auto /dev/sda1 /mnt and play around with the partition number, until the mounting succeeds.
When you found the correct device name, you could add an entry to /etc/fstab (read the man page for more info), so you can simply mount it as a non-root user.