Top of camera controls

Top of the camera are a variety of controls, at the top right of this image is the shutter release button surrounded by the zoom controller (not proportional, simply zoom in / zoom out). Below this is the drive control button (normal, continuous, self-timer, remote). Beside this is the main power / record / play dial with the mode sub-dial, each exposure mode is described in more detail below:

AUTO	Automatic Exposure Camera has complete control over exposure, point-and-shoot operation, the majority of manual features are disabled, you can't alter exposure compensation, ISO or use RAW mode.
P	Program Auto Exposure Very similar to AUTO exposure but you have access to all the normal manual controls, can set the ISO, exposure compensation, use AE lock, bracketing etc.
Tv	Shutter Priority Auto Exposure In this mode you select the shutter speed and the camera will attempt to select the best aperture for a proper exposure. Shutter speed is displayed on the LCD, press the left / right arrows to select different shutter speeds. A half-press of the shutter release causes the cameras exposure system to calculate the aperture, if it's outside of the cameras exposure range (for instance trying to take a shot at 1/500s in darkness) the aperture will appear in RED. The LCD view changes to reflect the look of the final image at this exposure. Available shutter speeds (40 total): 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 secs
Av	Aperture Priority Auto Exposure In this mode you select the aperture and the camera will attempt to select the best shutter speed for a proper exposure. Aperture is displayed on the LCD, press the left / right arrows to select different apertures. A half-press of the shutter release causes the cameras exposure system to calculate the shutter speed, if it's outside of the cameras exposure range the shutter speed will appear in RED. The LCD view changes to reflect the look of the final image at this exposure. Available apertures (13 total): F2.0, F2.2, F2.5, F2.8, F3.2, F3.5, F4.0, F4.5, F5.0, F5.6, F6.3, F7.1, F8.0
M	Full Manual Exposure In this mode you select the aperture and the shutter speed from any combination of the above. Left and right arrows select shutter speed, up and down arrows select aperture. The LCD view changes to reflect the look of the final image at this exposure. It appears as though the G1's metering system is disabled in this mode as there's no exposure meter as seen on other cameras.
	Pan-focus In this mode the focal length is locked to maximum wide angle (you cannot zoom). No auto focus is performed, instead the focus is locked (much like a fixed focus lens camera) which allows very fast (almost lag free) shots to be taken. Useful for situations when you need a fast reaction.
	Portrait In this mode apertures are kept as large as possible (small F number) to produce a blurred background to help define the subject in a portrait shot.
	Landscape In this mode the flash is by default disabled (although you can enable it) and focus is locked at infinity. Apertures are kept as small as possible (large F numbers) to produce the largest possible depth of field. Macro focus is also disabled. Designed to be used for taking landscape shots.
	Night Scene Known on other cameras as "Slow Sync Flash". Put simply in this mode slow shutter speeds are used to capture a dimly lit background (buildings at night for example) and the flash fires briefly to illuminate a foreground subject.
BW	Black & White Shoots in black & white.
	Stitch Assist Designed to make shooting of panorama / stitch shots easier. You have a choice of five different stitch modes: left-right, right-left, down-up, up-down or 4-frames in a square. The display changes to show previously shot frames in the sequence to help alignment of each frame. Exposure and White Balance are locked to the first frame.
	Movie Mode Shoot short (up to 30 second) movie clips @ 320 x 240. Audio is also recorded.

An excellent range of exposure modes makes the G1 a camera which can be used by the beginner, keen amateur and prosumer alike. A good range of shutter speeds, apertures and ISO's means that you should be able to shoot just about any type of shot in just about any situation.

The F8 situation

Those observant about you did indeed notice Canon's small print on the press release, under Shutter Speeds it said "Aperture value is fixed to F8 if users set the shutter speed from 1/640 to 1/1,000 s in Shutter priority AE mode or Manual mode.". Well, under testing I can confirm it's not possible to use shutter speeds 1/640, 1/800 or 1/1000s with any aperture other than F8. In any mode this exposure limitation seems to stick.

We asked Canon why the F8 limitation and this was their reply (direct from Tokyo):

The PowerShot G1 adopts a single mechanism that serves as both for the iris and the shutter. This mechanism releases the shutter by closing the iris diaphragm completely.

In this mechanism, the iris diaphragm must be closed quickly when releasing the high-speed shutter. The closing speed of the iris diaphragm, however, has a limit to keep the precision and the durability of the mechanism.

Because of the above-written limit of iris diaphragm closing speed, the iris aperture must be closed to some extent to shorten the moving distance of the iris diaphragm, when releasing the high-speed shutter. This is the reason why the aperture value is fixed to F8 when using the high-speed shutter of 1/640 sec. or higher in the PowerShot G1.

Rear of camera controls

On the back of the G1 you'll find the flip-out LCD with a variety of buttons surrounding it. Each of the buttons is described in more detail below:

Record Mode

	Flash Mode Toggles through the flash modes: Flash Off, Auto Flash, Flash On with Anti Redeye, Flash On (Fill-in). (The availability of different flash modes varies with the selected exposure mode). Flash mode is displayed on the top LCD and rear LCD (if enabled).
	Spot Metering Enables / Disables spot metering. Only available in P, Tv, Av and M exposure modes. When spot metering is enabled the camera meters only from a small rectangle in the center of the frame, this rectangle is shown on the rear LCD (if enabled). Spot metering status is displayed on the top LCD and rear LCD (if enabled).
	Macro Focus Switches the cameras autofocus system between normal focus range (70 cm +) and macro focus range (6/20 cm - 60 cm). Available in all exposure modes except Pan-Focus and Landscape.
	Auto Exposure Lock (AE-L) Takes an exposure reading and locks it for the next shot. Only available in P, Tv and Av exposure modes. Something very unique to the G1, if you have the flash enabled the camera will fire the flash and take a meter reading against the flash output, lock it and use it for the next shot. Once the shot is taken metering is reset.
	Multifunction Button This button scrolls between four different camera settings: Exposure compensation: +/-2 EV in 0.3 EV steps White balance: Auto, Sunny, Cloudy, Incandescent, Fluorescent, Manual Preset Bracketing: 3 frames: 0/+/- 0.3, 0.7, 1.0, 1.3, 1.7 or 2.0 EV Flash output compensation: +/-2 EV in 0.3 EV steps Use the left / right arrows to select different values.
DISPLAY	Display Mode Toggles between three LCD display modes: No display, Image only display, Image and camera settings display.
SET	Setting / Menu confirm Used to confirm changed camera settings or options in the camera menus.
MENU	Enter / Leave the Record Menu

There is a "delete before saved" shortcut just like on the S10 / S20, if you're looking at an image review, press SET then * to call up the delete yes/no dialog.

Play Mode

	Toggle Thumbnail view Toggles between display of full screen image or 3 x 3 thumbnails on the LCD screen.
	Playback Zoom Zoom the displayed image either 2.5 or 5.0 times, the 4-way controller can be used to scroll smoothly around the zoomed image.
JUMP	Jump Jump through playback images by 10 frames forward or backward.
DISPLAY	Display Mode Toggles between three LCD display modes: Image only display, Image and brief frame information, Image and detailed exposure information.
SET	Setting / Menu confirm Used to confirm changed camera settings or options in the camera menus.
MENU	Enter / Leave the Play Menu