Casio has integrated a spherical lens and a high-sensitivity CCD into a single component. The lens has a maximum aperture of F3.5 and a fixed focal length of equivalent to a 37mm lens on a 35mm cameras. It is a non-auto focus (fixed focus) lens with a range of 31.5 inches to infinity in normal mode and can focus as close as 11.8 inches in macro mode. The lens has a builtin protective shutter that closes when the camera is powered down.

The optical viewfinder is bright but somewhat barrel distorted with a fairly narrow viewpoint, it shows approximately 85% of the captured image. There is no diopter adjustment.

The built-in flash has modes for auto, fill, red-eye reduction and off. The working range is approx. 2.6 to 4.9 ft.

Located on the top are the power on/off and shutter release buttons.

The controls are minimal but effective. Above the LCD is the focus switch with positions for normal and macro distances. All camera settings are changed via onscreen menus called up by the MENU button and selected with the 4-way controller. The operating mode is selected with the PLAY - RECORD switch. The DISPlay button turns the 1.6-inch color LCD on/off. The 4-way controller is also used to activate the digital zoom (if enabled.)

The EX-S20 has 10 megabytes of internal memory for saving images and movie clips. Optionally, any size Secure Digital or MultiMedia Card can be used via the expansion slot on the bottom. Image data can be copied to/from internal memory and a flash card via the Playback menu.

The camera must be placed in the included cradle to connect with a computer via the built-in USB 1.1 port and transfer data.   It also charges the battery.

On the front of the cradle is a "PHOTO" button that starts an automated slideshow display of the images in the camera. The CHARGE light is red during charging and green when the battery is fully recharged. The USB indicator lights up when the cradle is connected to the host PC.

The super-slim NP-20 lithium battery pack is charged whenever the camera is docked in the cradle. This 3.7 volt battery is rated at 680mA and Casio claims it will power the camera for 180 minutes in playback or 95 minutes (approx. 190 shots) in record mode with the LCD turned ON and not using the flash.

Recharging time is approx. two hours if the battery is fully depleted.