The all-glass Canon 7.1-21.3mm 3x zoom (35-105mm 35mm equivalent) boasts a maximum aperture of f/2.8-4.9, and is constructed with 8 elements in 7 groups.

Focus range is 80cm (32.7 in.) to infinity in normal mode. Macro autofocus range is 6cm (0.2 ft.) (wide-angle) / 20cm (0.7 ft.) (telephoto) to 70cm (2.3 ft.).

The autofocus is accomplished via a three-point TTL system with user-selectable AF points visible on the LCD monitor. The S40 also features an AF assist illuminator for accurate focusing even in dim to dark environments.

When powered down or in sleep mode the lens is retracted back into the camera body. The camera is powered on when you slide the front cover open.

The Manual focus option is enabled by pressing and holding the "MF" button while using the Up or Down on the 4-way switch. The manual focus range is 6cm (0.2 ft.) (wide-angle) / 20cm (0.7 ft.) (telephoto) to infinity. While manually focusing, the subject area covered by the active focusing point is digitally enlarged on the LCD to aid in critical focusing.

To save battery power or when outdoors in the bright light, switch off the LCD and frame your shots with the eyelevel optical viewfinder. There is no diopter adjustment. The LEDs on the side indicate recording, autofocus and flash status. The eyelevel finder shows approximately 87% of the captured image.

The builtin 5-mode (Auto, Redeye, Slow-sync, On, Off) flash will handle most average picture taking tasks. It has a maximum range of 13 feet (3.96m)

The zoom lens control is along the edge in front of the shutter button and the Mode Dial.   Next to the Mode Dial is the 4-way selector switch and below it is the Play mode switch.

The Mode Dial has positions for:

• Manual - you set both the shutter speed and aperture
• AV (Aperture priority) - the camera automatically selects a shutter speed to match the aperture you set. Aperture settings available are: F2.8, F3.2, F3.5, F4.0, F4.5, F5.0, F5.6, F6.3, F7.1, F8.0
• TV (Shutter priority) - camera automatically selects an aperture setting to match the shutter speed you set. Available shutter speeds are: 1/1500, 1/1000, 1/800, 1/640, 1/500, 1/400, 1/320, 1/250, 1/200, 1/160, 1/125, 1/100, 1/80, 1/60, 1/50, 1/40, 1/30, 1/25, 1/20, 1/15, 1/13, 1/10, 1/8, 1/6, 1/5, 1/4, 0.3, 0.4, 0.5, 0.6, 0.8, 1, 1.3, 1.6, 2, 2.5, 3.2, 4, 5, 6, 8, 15 seconds
• Program AE - camera automatically set the shutter speed and aperture settings like AUTO but the user can change many options like white balance, exposure compensation, saturation, sharpness and more.
• AUTO - camera sets everything automatically, this is "point and shoot" mode

The pre-programmed "Image Zone" modes include:

• Portrait - Sets a large aperture value to have a minimum depth of field so your subject is sharp but the background gets blurred.
• Landscape - Sets the focus to infinity and uses a small aperture
• Night Scene - Uses slow shutter speed (tripod recommended) to capture night backgrounds and synchronizes the flash to illuminate foreground subjects
• Sports - When you need to capture fast moving subjects
• Color Effects - Vivid, Neutral, B&W or Sepia tone
• Stitch Assist - The user will be aided by the LCD when creating multi-image panorama pictures. Five types of assistance are available:
  1. Horizontal - left to right
  2. Horizontal - right to left
  3. Vertical - top to bottom
  4. Vertical - bottom to top
  5. Clockwise starting at top left.
  
  
  
  
  Onscreen view of Stitch Assist mode
  
  

• Movie - capture full motion video and sound clips up to 30 seconds in length at 320 x 240 resolution at a rate of 15fps or up to 120 secs at 160 x 120 resolution.
  
  
  

  
  

  
  

  Across the top is the Flash mode button (thumbnail index button in Play mode), Macro focus mode button (the Jump button in Play mode), the slide switch to the right of the optical finder puts the camera into Play mode. The 4-way controller lets you navigate menu screens, when pushed in the center it is the SET button. When in Record mode the SET button is used to change the active Focus Point.

  The Menu button calls up the onscreen menu system, The DISPLAY button controls the color LCD and the amount of data that is overlayed on it.

  Along the left side of the LCD is the combination Exposure Compensation / White Balance / Flash Compensation and AE Bracketing button, push it to cycle through the modes and change them onscreen. The "MF" toggles the manual focus mode when held (in Play mode this is the single image Delete button. The bottom button cycles through the AE metering modes.
  
  
  

  
  

  
  

  Located on top of the camera are the builtin microphone and speaker.
  
  
  

  
  
  

  The I/O ports are also on the left side:
  

  
  The A/V OUT handles both the audio and video (NTSC or PAL, selectable).

  
  The lower connector is for the USB data cable.
  
  
  

  
  

  
  

  On the bottom in the battery compartment is the Compact Flash Type II card slot. The S40 is supplied with a 16MB CF card and can use any Type I or II solid state flash memory card or one of the IBM Microdrives. The card is ejected far enough to be easily removed, even Microdrives.
  
  
  

  
  

  
  

  The S40 is powered by a NB-2L lithium rechargeable battery pack.   A fully charged battery is good for approximately 170 images when using the LCD or up to 380 images when you use only the optical viewfinder. Or a playback time of approximately 300 minutes.
  
  
  

  
  

  
  

  The NB-2L pack is charged out of the camera in the included CB-2LT Compact Charger (100-240VAC). Charging time is approx 80 minutes or less. It plugs straight into an AC outlet, no cords required.