Canon PowerShot A640

Reviewed April 2007

Introduction

From the PowerShot A620 springs the Canon PowerShot A640 and A630, both of which retain the same body design and 4X optical zoom as the A620, but with the addition of a 2.5-inch LCD monitor and an increase in resolution: the A630 to 8 megapixels, and the A640, the focus of this review, to 10 megapixels.

While the exterior shape of the A640 is roughly the same as the A620, this model sports a dark-gray metallic finish with a lighter gray grip, as well as a metallic lens barrel and lens trim — the latter being removable to accept a conversion lens adapter.

The 2-stage Shutter Release with the Zoom Lever around it are perched at the top front part of the grip, making both easily accessible. Pushed to the left, , the zoom control moves the zoom to the wide angle end, and when the camera is in playback it serves to display the Index view, , placing 9 thumbnail images per screen. When pulled a second time, it allows jumps of 9 images at a time forwards or backwards. Pulling the zoom control to the right, , moves the lens to the telephoto end, while when the camera is in playback mode it serves to zoom () into an image on screen up to 10X. In addition, when the SET button is pressed (see further), it is possible to go to the next image with the same level of magnification.

The Mode Dial is also positioned on top of the camera, with the On/Off button nearby. The Mode Dial has 12 positions separated into 2 groups: the Creative Zone, which begins with the Program mode and ends with the Custom position, and the Image Zone, which starts with the Portrait mode below the Auto mode, and ends with the Movie mode. The Auto mode is intended as the simplest mode, designed to make the A640 a point-and-shoot:

	The Auto Mode takes care of all settings, and all the user has to worry about is selecting the image size and quality, the flash mode, the self-timer and whether the Auto sensitivity should be set to its default, or the High range (see further).
	Program AE allows the camera to choose the aperture and shutter speed but leaves all other capture parameters up to the user.
	Shutter Priority allows selecting the shutter speed from a range that covers from 1/2500 second to 15 seconds, the precise upper value available depending on the zoom position, while the camera selects a corresponding aperture.
	Aperture Priority lets the user control the depth of field by selecting the aperture from a range that starts at f2.8 when the zoom is at the wide end, and f4.1 at the telephoto end, closing down to f8 for both, while the camera matches the selection to a shutter speed.
	Manual Mode provides complete control over all parameters and offers an exposure indicator to guide the user. The shutter speed range is the same as the Tv mode's, varying along with the zoom position for the upper range, and extending to as long as 15 seconds. And the aperture range is the same as is available with the Av mode.
	Custom makes it possible to pre-set a complete set of preferred settings — including the shooting mode: P, Tv, Av or M — and recall them at any time by selecting the Custom mode again.

The remaining modes are positioned on the other side of the Auto mode, starting with the Scene Modes:

	Portrait uses a wide aperture to shorten the depth of field and blur the background, emphasizing the subject, an effect that is more pronounced if the zoom is set to the telephoto end.
	Landscape forces a small aperture to maximize depth of field. The shutter speed can be quite slow, so the use of a tripod is recommended.
	Night Scene uses a slow shutter speed (1 second maximum) and the flash to capture both the foreground and the background. The flash mode can be changed or even set to Off, and the camera automatically adjusts the sensitivity.
	When the Mode Dial is set to this position, it is possible to choose any of 8 additional Scene modes using the 4-direction control: Night Snapshot is designed to capture people in front of a twilight or night background and reduce the effect of camera shake even without the use of a tripod. Kids and Pets optimizes the shutter speed and sensitivity to allow capturing subjects that move around. Indoor adjusts the white balance so that images can be shot with accurate colour under either fluorescent or tungsten (incandescent) lighting. Foliage enhances colour saturation to capture subjects such as autumn leaves or blossoms. Snow compensates the exposure so that people are correctly exposed against a bright snow backdrop. Beach also compensates the exposure for a highly reflective environment such as water and sand. Fireworks sets the shutter speed to 2 seconds and the focus to infinity to capture a fireworks display (the use of a tripod is necessary). Underwater applies a colour correction so that the image shows natural colours when images are captured using the optional waterproof case (WP-DC8). Colour Accent allows selecting a colour in a captured image displayed on the monitor, and saving the image with only that colour while all others are changed to black and white. Colour Swap allows selecting one colour in an already captured image, and then replacing it by another.
	Stitch Assist Mode serves to capture a series of frames that overlap slightly so that they can be assembled into a larger image later using the software included with the A640.
	The Movie Mode makes it possible to capture video clips in any one of four ways: Standard movie mode allows choosing the resolution (640 x 480 or 320 x 240 pixels) as well as the frame rate (30 fps or 15 fps). The mode allows the use of the 4X digital zoom, and the length of the recording is only limited to 1 GB. Compact serves to capture a low resolution (160 x 120 pixels) movie at 15 fps for up to 3 minutes, making the movie suitable as an attachment to an e-mail. Colour Accent is like the still image mode of the same name, and allows selecting one colour on the monitor that will remain while all others will be switched to Black and White. The maximum movie length is 1 GB. Colour Swap transforms a colour specified on then monitor into another colour. The maximum movie length is 1 GB. Whatever the movie type, the optical zoom position is locked at the first frame, as is the focus, but the exposure and white balance are adjusted as needed as the recording progresses. Sound is recorded in mono.

The LCD monitor of the PowerShot A640 measures 2.5 inches (6.35 cm) diagonally, and is composed of 115,000 pixels, which gives it an average resolution.

Starting with the monitor closed on the back of the camera, it is possible to open it towards the right 180°, then rotate it towards the front of the camera, and then swing it back onto the back of the A640. Alternatively, once fully opened to the left, it can also be rotated 90° downwards, making it possible to hold the camera overhead and still see the monitor.

In addition, the PowerShot A640 provides an optical viewfinder which has an etched AF cross at the centre. The viewfinder is centred at the top of the camera. Two LEDs are embedded on its right.

The upper one glows green when the focus is locked, and blinks green while an image is being stored. In addition, the top LED also serves to indicate the flash is needed, blinking orange when the flash is forced off but required, and solid orange when the the camera is going to use the flash and it is charged.

The lower LED blinks yellow when the camera is unable to focus, and remains solidly lit yellow when the macro mode, manual focus mode or the AF Lock are used.

The next control on the back of the A640 is the Mode Switch. The Mode Switch has two settings: pushing the switch to the left leads to the Playback mode, indicated by the usual icon , and pushing it towards the right leads to the Recording mode, marked by a red camera symbol .

The next button down on the left controls Exposure Compensation.

Exposure compensation is available in all modes except Auto and Movie and covers a range of ±2 EV in 1/3 EV increments. With the camera set to the Manual mode, the exposure compensation button serves to toggle back and forth between aperture and shutter speed, making it possible to set both. In addition, this button also serves as an AE-Lock (Auto Exposure Lock) or an FE-Lock (Flash Exposure Lock) when the flash is forced on.

With the A640 set to the Playback mode, the same button can be used to delete the image currently under review on the monitor, or the highlighted image using the Index screen.

The other button, on the right, only has a single function, available only when the camera is connected to a printer, or to a computer that has the software supplied with the A640 installed:

Connected to a computer, the button displays a short menu screen with five options:

Separating these two buttons from the other two below, the 4-direction control serves to browse the menus, or the images captured with the A640. At its centre, a button labeled FUNC. SET serves to superimpose the Function menu on the monitor (see the Characteristics section of the review for details about the Function menu), or to confirm a selection made in one of the menus. Moreover, two of the four directions of the 4-direction control access functions:

With the A640 set to the Recording mode, the up arrow serves to select the Flash mode: Auto, Auto with Red-eye Reduction, Forced On with Red-eye Reduction, Forced On, or Forced Off.

In Playback mode the button makes it possible to speed through images on the memory card when the Index view is used (see above), the up and down arrows then serve to choose one of the 4 JUMP modes: Jump 10 Images: jumps 10 images at a time. Jump 100 Images: jumps 100 images at a time. Jump Shot Date: jumps to the first image of each shooting date. Jump to Movie: jumps to a movie. Jump to Folder: jumps from the first photo in a folder to the first photo in the next folder. While the right and left arrows jump the selected number of images.

The down arrow controls the Focus modes: Macro mode which has a focus distance of 1 cm (0.39 inches) from the front of the lens when the zoom is at the wide angle end, and from 25 cm (9.8 inches) when the zoom is at the maximum telephoto setting. The Manual Focus mode, which superimposes a distance scale at the top of the screen, and if desired magnifies the centre part of the image to make focusing easier.

The last two buttons, below the 4-direction control, serve to call up the MENU, while the other, DISP., controls the information overlaid on the monitor:

• By default, in the Recording modes the image on the monitor has basic camera settings superimposed on it: AF area, capture mode, drive mode, ISO, metering pattern, compression and image resolution, flash mode and the current battery state. And, when the shutter release is pressed halfway, the shutter speed and aperture are indicated at the bottom.
• A first press of the DISP. button turns off the monitor, a good power-saving strategy when the optical viewfinder is used.
• A second press of the button turns the monitor back on, but only with the AF point and the exposure compensation value superimposed. Still, as with the default setting, the aperture and shutter speed are indicated when the shutter release is pressed halfway.
  
• In the Playback mode, by default, the image is shown with its file name at the top, and its position within the images contained in the folder, its resolution/quality settings and the date and time at which it was captured at the bottom.

• Pressing the DISP. button once reduces the image to a large thumbnail, presenting it in the upper left corner with potentially overexposed ares flashing black/white, and adds the capture mode, ISO, shutter speed , aperture, exposure compensation, flash compensation, white balance, metering mode, resolution and compression, file size and a histogram showing the distribution of brightness in the image.

• Pressing the DISP. button a second time simply presents the image by itself, free of any superimposed information.

The PowerShot A640 offers well laid out controls and is comfortable to use. It has a large grip that provides a good hold on the camera. It also offers a large monitor, albeit one with average resolution, which makes the menus and other indicators very legible, even in bright outdoor light. Moreover, the fact that the monitor can be rotated and positioned so as to be always visible makes it possible to capture shots of all types of subjects.