The PowerShot S2 is not a mass storage device so you can't just mount it to get the pictures. Instead it uses the Picture Transfer Protocol (PTP). A userspace tool which speaks this protocol is gphoto2. The PowerShot S2 is supported since version 2.1.6.

The 2.1.6 release is only available in the unstable branch:

#> apt-get -t unstable install gphoto2

or under Gentoo (the rest of the directions here work just fine under gentoo (thanks to original poster)).

{~} $ emerge gphoto2

To make it work for non-root users do the following to let hotplug set up the correct permissions for you:

#> /usr/lib/libgphoto2/print-usb-usermap |sed -e 's/^usbcam/libgphoto2/' > /etc/hotplug/usb/libgphoto2.usermap

The above step makes sure all cams supported by libgphoto2 are known to the hotplug daemon. Debian uses a different script than the default install thus the sed. The rest needed should be set up by the debian package already. If not refer to the gphoto2 manual. The only thing left is to add the users which are allowed to access the cam to the group camera.

Connecting the camera should print the following in the syslog:

Jul 30 16:47:09 rumpel kernel: usb 1-4: new high speed USB device using address 12
Jul 30 16:47:09 rumpel usb.agent[23381]:      libgphoto2: loaded successfully

Try your luck with the autodetection and you should see this:

$> gphoto2 --auto-detect
Model                          Port                                            
----------------------------------------------------------
Canon PowerShot S2 IS (PTP mode) usb:            
Canon PowerShot S2 IS (PTP mode) usb:001,012

The hotplug method mentioned above doesn't work anymore with a recent kernel and a matching udev version (udev replaces hotplug). I had to use the following rule placed in /etc/udev/rules.d/10-local.rules:

BUS="usb", SYSFS{idVendor}="04a9", SYSFS{idProduct}="30f0", GROUP="camera", MODE="0660", \
  PROGRAM="/bin/sh -c 'K=%k; K=$${K#usbdev}; printf bus/usb/%%03i/%%03i $${K%%%%.*} $${K#*.}'", \
  NAME="%c", RUN="/bin/sh -c 'chgrp camera /proc/%c && chmod 0660 /proc/%c'"

The rest is the same, add your user to the camera group and use gphoto2 –auto-detect –list-files to test.

You could of course use some GUI like the gtkam utility but I prefer a little script to do what I want. It fetches all available images to the current directory, autorotates them lossless using exiftran and deletes all images from the camera.

#!/bin/sh
 
#The cameras image folder. use '--list-files' to get the name of the image folder
FOLDER='/store_00010001/'
 
echo "fetching all files..."
gphoto2 --auto-detect --get-all-files --folder $FOLDER
 
echo "Autorotating images..."
exiftran -ai *.JPG 
 
echo
echo "Deleting images from camera (Abort now if not wanted)"
echo -n "Hit enter to continue "
read foo
 
gphoto2 --auto-detect --delete-all-files --recurse --folder $FOLDER

Bus 001 Device 007: ID 04a9:30f0 Canon, Inc. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x04a9 Canon, Inc.
  idProduct          0x30f0 
  bcdDevice            0.02
  iManufacturer           1 Canon Inc.
  iProduct                2 Canon Digital Camera
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           39
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xc0
      Self Powered
    MaxPower                2mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass         6 Imaging
      bInterfaceSubClass      1 Still Image Capture
      bInterfaceProtocol      1 Picture Transfer Protocol (PIMA 15470)
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval              10
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  bNumConfigurations      1