The Stylus 820 is equipped with an Olympus aspherical glass 5x zoom lens, 6.4 - 32.0mm (36 - 180mm equivalent in 35mm photography), 8 elements in 6 groups with 4 aspherical lenses. It has a 5.6x digital zoom feature. The maximum aperture is F3.3 (W) / F5.0 (T). The lens retracts into the camera when powered down and is protected by an automatic lens barrier.

The CCD contrast-detect auto focus system covers from 27.6" (0.7m) to Infinity in Normal mode, while Macro mode covers from 7.9" (0.2m) to infinity in Wide angle, 23.6" (0.6m) to infinity in Telephoto. Super Macro mode gets you as close as 1.2" - 27.6" (3cm-70cm).

The built in speedlight features Auto, Red-eye reduction, Fill and Forced Off modes. The maximum flash range is 12.8 ft. (3.9m) Wide / 8.5 ft. (2.6m) in Telephoto, using ISO 800.

There is no optical viewfinder, you frame, review and perform menu operations on this large 2.7-inch HyperCrystal LCD monitor with approx. 230,000 pixels of resolution. It delivers a high contrast image with a 160° wide-view radius.

Controls on the back: Top is the zoom lens control which also functions as the magnified playback and index mode buttons when in play mode. The Mode Dial has positions for Favorites (green start), Playback, Record, DIS mode, Scene, Guide and Movie. The MENU button calls up and dismisses the menu system, while the play button enters playback mode (also sets DPOF settings when in playback mode). The 4-way selector is used to navigate menu screens and select images for playback. In record mode the "Up" button changes exposure compensation, "Left" enables the macro focus modes, "Right" changes the flash mode and "Down" button enables the self-timer. The DISPlay button selects the amount of overlay information on the LCD image. The Shadow Adjustment/trash can button is used to delete images in playback mode. The "Shaking Hand" button turns the Shadow Adjustment mode on and off in record mode, and deletes images in playback.

On the top is the Power button and Shutter Release.

The multi-connector I/O port handles optional AC power adapter (DC IN 4.8V), A/V output (NTSC or PAL format) as well as Data I/O via a Mass Storage compliant USB (2.0 High-speed) connector, which is also PictBridge compatible for direct printing.

A black rubber O-ring goes around the I/O port door. The camera is "weatherproof and is not damaged by water spray from any direction" as long as the rubber ring is intact and the I/O port door is properly closed.

Still images and movie clips are stored in the camera's ~47MB of internal memory or on removable xD-Picture Card flash memory cards. Olympus brand xD-Picture Cards are required to use the camera's built-in Panorama feature. 16MB to 2GB xD-Picture cards are now available.

Power is supplied by a LI-42B 3.7v 740mAh Li-ion battery pack. Olympus does not specify the battery runtime. The included AC charger lets you charge one battery while using another. Lithium battery packs can be charged or "topped off" at any time without shortening the service life of the battery.