Testing/ Performance
The 1/2.5-inch CCD has 7.4 total and 7.1 effective megapixels and is shacked up with a brand new Digic III processor. The new image processor is credited with speeding up startup and burst times, along with adding a whole new face recognition system. The technology recognizes faces that are looking at the camera straight on and tracks them if they move. The camera then assures that faces are in focus once the shutter release button is pushed halfway. The SD800 IS did everything its press materials said it would, which is a rarity. The camera actually recognized and tracked faces quickly and kept them in sharp focus. Besides the sensor and processor technology, the Canon PowerShot SD800 has an optical image stabilization system that is also very effective. Nothing has been changed in this system from the earlier SD700 IS; it still has several modes and works extremely well in keeping movies smooth and pictures nearly blur-free.
Viewfinder 
The SD800 has a real image optical viewfinder that zooms along with the lens. It is not entirely accurate, but it is one of the better optical viewfinders I’ve seen in terms of accuracy. The viewfinder does not see the entire recorded picture, but at least its view is almost centered with the final product. If you frame a subject, you will just end up with some extra space above the head and below the feet. The glass itself isn’t the most high-quality; it looks a little bit blurry. Overall, the optical viewfinder is not as bad as some other optical viewfinders found on Digital ELPH cameras.
LCD Screen
The Canon PowerShot SD800 IS has a 2.5-inch low temperature polycrystalline silicon TFT color LCD screen. Although the SD800 LCD monitor is same size as on the SD700, the new model has an upgrade in resolution of 207,000 pixels over the SD700’s 173,000 pixels. This isn’t the most fabulous resolution on the market, but it is quite decent. The LCD screen offers 15 brightness adjustments in the setup menu and a nice wide view from all four angles (not diagonal though). The SD800’s LCD has a 100 percent view of the recorded image. The view on the LCD screen allows users to see the full frame, face tracking and auto focus system brackets, and file information. There is a Disp. button to the bottom left of the multi-selector that changes the view on the screen to include basic or full shooting information as well as turning the screen off.
Flash 
Placed in the top right corner of the front of the Canon SD800 is the built-in flash unit. The rectangular flash gets in the way of the left fingers when handling. When the fingers are not blocking the unit, the flash can light up subjects within 1.6 - 13ft. at the widest focal length and 1.6 - 6.6ft. at the most telephoto focal length in the lens. In the macro mode, the flash can light up subjects from 1 - 1.6ft., but none of the pictures I took in the macro mode with the flash turned out any good. The flash output can not be adjusted and it looked much too bright at that distance.
The right side of the multi-selector changes the flash modes: Auto, On and Off. This list sounds much too short, but that’s because the red-eye reduction and slow synchro modes are located in the recording menu and can be turned on and off there. When subjects are at an appropriate distance from the camera, skin tones are retained and the flash doesn’t make them look horribly unnatural. Canon listed its flash recharge time at 10 seconds or less, but it proved to lean toward the “or less” taking about 2-3 seconds between shots.
Zoom Lens
The older model, the SD700 IS, had a 4x optical zoom lens, so the SD800 IS’s 3.8x lens is a bit shorter. It is also wider. The focal lengths reach from 4.6 - 17.3mm, or an equivalent 28 - 105mm. This makes it easier to fit large groups into the frame without backing up and backing up and backing up. It also squeezes great landscape shots and such into one frame without requiring a stitch assist mode (although those are on the camera too). The Canon zoom lens is controlled by a tight zoom ring that surrounds the shutter release button. When the ring is tapped, there are 7 stops in the zoom range. The zoom range is not very good, as most cameras with a 3x range get 6 stops of focal lengths. The poor control is seen when zooming on the live preview. It is hard to frame a subject when the lens moves out and in quickly to its closest “stop.” There is no on-screen indicator of where users are currently in the zoom range. The camera has maximum apertures of f/2.8 - 5.8. The aperture lets in plenty of light at the 28mm focal length, but it very limited otherwise, although it does not seem to affect the camera’s performance. The limited aperture is something to keep in mind should you push its low light capabilities while zoomed on a subject. 
The Canon PowerShot SD800 IS has an optical image stabilization system that operates a few different ways. It can be set in the recording menu to turn on when shooting only or to work continuously. The IS system can be optimized to stabilize horizontally only with the “Panning” mode or it can be turned off altogether. The system is so effective though that it really should not be. It keeps video looking smooth and reduces the number of blurry pictures from the camera.
