Canon PowerShot A640

Reviewed April 2007

Characteristics

The maximum image size of the PowerShot A640, 3648 x 2736 pixels, is produced by a 1/1.8 inch CCD with 10.4 million pixels of which 10.0 million pixels are effective. A total of 7 image formats are available to the user:

Any of these image sizes can be combined with any one of three JPEG compression levels, but a non-lossy format is not offered:

• Superfine: the highest image quality applies a compression with a ratio that averages around 7:1.
• Fine: an average compression level, applying a compression that is commonly at approximately 12:1
• Normal: the strongest compression, compressing images to a ratio of about 20:1.

Starting at 80 ISO, the sensitivity range of the CCD covers 100, 200, 400, and 800 ISO, when the A640 is set to P, Tv, Av or M modes. An Auto ISO setting that allows the camera to automatically set the sensitivity according the ambient light conditions is also available, and is the default mode for the Auto shooting mode and the Scene modes. In addition, a High ISO Auto is also available with the Auto Shooting mode.

The Canon zoom lens of the PowerShot A640 has a focal length range of 7.3 to 29.2 mm, equivalent to a 35 to 140 mm on a 35 mm camera. The maximum aperture at the wide angle end is f2.8, while at the telephoto end it becomes f4.1. In all cases, however, the aperture range extends to f8, although under some circumstances the Auto mode is capable of apertures of f11 and even f16, depending on the zoom position.

The toothed ring around the base of the lens barrel can be released using the button to the lower right of the lens, making it possible to clip on a lens adapter, LA-DC58F, onto which 58 mm diameter filters, or optional conversion lenses (Wide Converter C-DC58N, or Tele-converter TC-DC58N) can be mounted.

As noted in the Ergonomics section of the review, the A640 has an overall shutter speed range that covers from 1/2500 second down to 15 seconds. The top end of the range, however, can be as low as 1/1250 second depending on the zoom position. With low shutter speeds — 1.3 seconds or longer — noise reduction processing is automatically applied to the image before it is saved.

As with other PowerShot cameras, frequently needed camera settings are contained in the Function Menu, a menu that appears superimposed on the image on the monitor in all modes (note that the menu animation shown below is purposefully shown on a black background for legibility). But, while the Function menu is presented in all modes, only the Creative zone modes offer full access to all its options:

• ISO Speed: Auto, 80, 100, 200, 400, 800 ISO; and only Auto and High ISO Auto when the camera is set to the Auto shooting mode.
• White Balance: Auto, Day Light, Cloudy, Tungsten (incandescent), Fluorescent (warm), Fluorescent H (daylight), Underwater and Custom (measured under ambient light by basing the white point on a white surface).
• Drive Mode:
  • Single
  • Continuous: captures photos at 1.5 frames per second using a Large/Fine image size. If a high speed memory card is used, the camera can keep shooting until the card is full or the batteries are exhausted.
  • 10-second Self-Timer.
  • 2-second Self-Timer.
  • Custom Self-Timer provides a selectable delay time (0 through 10 seconds, or 15, 20, 30 seconds) and a choice of the number of photos to take (1 to 10).
• My Colours: provides control over the way colours are recorded:
  • Off: the default.
  • Vivid: emphasizes colour saturation and contrast.
  • Neutral: decreases colour saturation and contrast.
  • Sepia: captures the image with sepia (brown) tones.
  • Black and White: captures a gray scale image.
  • Positive Film: enhances reds, greens and blues.
  • Lighter Skin tone: lightens skin tones.
  • Darker Skin Tone: darkens skin tones.
  • Vivid Blue
  • Vivid Green
  • Vivid Red
  • Custom Colour allows adjusting freely contrast, saturation, sharpness, colours (red, green and blue) and skin tones.

• ± Flash: provides flash exposure compensation (±2 EV in 1/3 EV increments) when the A640 is set to Program, Portrait, Landscape, Night Scene, and Av or Tv when the Flash Adjust option in the menu (see further) is set to Auto. Alternatively, when the Flash Adjust option is set to Manual, or when the Manual shooting mode is used, the flash output can be adjusted in increments to 1/3 power, 2/3 power or Full power.

• Metering Mode: serves to select the metering pattern:
  • Evaluative.
  • Centre-Weighted.
  • or Spot, which can be tied to the Flexizone AF point (see further).
• Compression: Superfine, Fine or Normal (see above).
• Frame Rate (Movie): serves to select the frame rate, either 15 frames per second or 30 frames per second (see the Ergonomics section of the review).
• Recording Pixels (Still image): as outlined above.
• Recording Pixels (Movie): 640 x 480, 320 x 240 or 160 x 120 pixels (see the Ergonomics section of the review).

The other menu of the A640 is called up by pressing the MENU button on the lower right of the camera's back. With the A640 in a capture mode, the REC. menu is presented in the first of three sections, each identified by a tab at the top of the screen:

• AF Frame: offers 3 auto focus options:
  • AiAF: lets the camera select the focus point(s) using one or more of the 9 AF points clustered near the middle of the frame.
  • Centre: uses the centre AF point exclusively.
  • FlexiZone: allows moving the focus point to any position in the frame using the 4-direction control.
• Digital Zoom controls the digital zoom and provides the following options:
  • 1.4X: applies the digital zoom to all focal lengths, changing the effective length of the lens to a 49 - 196 mm equivalent.
  • 2.3X: applies the digital zoom to all focal lengths, changing the effective length of the lens to a 80.5 - 322 mm equivalent.
  • Standard: extends the optical zoom by the 4X digital zoom for a total magnification effect of 16X.
  • Off: the default setting.
• Flash Sync: decides whether slow synchro flash (see next option) fires at the beginning of the exposure (first curtain), or just before the end of the exposure (second curtain).
• Slow Synchro: On or Off. Enables the Slow Synchro flash mode.
• Flash Adjust: Auto or Manual. This option is only accessible when the camera is set to Tv or Av modes and allows selecting either Auto, which provides for flash exposure compensation with the ± Flash option of the Function menu, or set to Manual, which then offers an adjustment over 3 steps for the flash output in the ± Flash option of the Function menu.

• Red-Eye: On or Off. When set to On, the orange lamp that also serves as the AF-assist lamp and Self-timer lamp is used to minimize red-eye.
• Spot AE Point makes it possible to associate the spot meter to the AF point when the FlexiZone AF is used (this option can only be accessed when FlexiZone is active).
• Safety Shift: On or Off. When the camera is set to Av (Aperture Priority) or Tv (Shutter Priority) this function ensures that a workable combination of aperture and shutter speed are used should the selected combination not be effective.

• MF-Point Zoom: On or Off. Decides whether or not the centre portion of the image is magnified to help in focusing when the camera is set to Manual focus.
• AF-assist Beam: On or Off. Controls whether or not the camera automatically uses the bright AF-assist lamp when the ambient light is insufficient for the auto focus system to work.
• Review: controls the display of a just-captured image. Four options are available, Off, Hold, which leaves the image on screen until a camera button is touched, or preset times of 2 or 10 seconds.
• Save Original: On or Off. Decides whether or not the original — unaltered — image is saved as well as the processed one when either the Colour Accent or the Colour Swap modes are used.
• Reverse Display: On or Off. Decides whether or not the camera automatically reverses the image from left to right when the monitor is facing the front, as would be the case with a self-portrait.
• Display Overlay offers three settings:
  • Grid Lines: divides the screen into 9 equal areas as an aid to composition.
  • 3:2 Guides: grays out the top and bottom of the frame to help frame a 3:2 image without having parts of the image cropped out when the image is printed.
  • Both: displays 3:2 guides and grid lines.
• Date Stamp: Off, Date, Date and Time. Only available when the camera is set to the Postcard image format, it serves to decide whether the Date only, or the Date and Time or nothing will be permanently imprinted atop the image.
• Save Settings: saves the current configuration of settings so that it can be recalled entirely when the Mode Dial is turned to the C (Custom) mode.

The next section of the menu is Setup. The options contained in this menu are covered in the Interface and Software section of the review.

The last section of the menu displayed when the camera is in a capture mode is called My Camera. This section contains 5 options that serve to configure the sounds produced by the A640 when it is operated, and the image displayed when the camera starts as well as the sound it makes. The camera comes with one preset image, and one preset sound for each option, but with the A640 connected through USB to a computer running the software Canon supplies with it, the preset sounds and image can be modified.

Unlike the capture mode's three part menu, the Playback mode of the A640 contains four sections. The first section contains the playback options:

• Auto Play: plays back all the images on the card with a 3 second interval.
• My Colours allows adding effects to already captured images: Vivid, Neutral, Sepia, Black and White, Positive Film, Lighter Skin Tone, Darker Skin Tone, Vivid Blue, Vivid Green, Vivid Red.

• Sound Memo: makes it possible to attach a sound recording, up to 1 minute long, to an already captured image.
• Protect: tags images so that they cannot be accidentally deleted. Formatting the card, however, will delete all images including those that have been protected.
• Rotate: serves to rotate an image by 90° or 270°.
• Erase All: erases all images on the memory card, with the exception of those that have been protected.

• Transfer Order: serves to identify images that should be transferred automatically when the A640 is connected to a computer running the software included with the camera.

The second section serves to decide which images will be printed and how, and starts direct printing when the camera is connected directly to a PictBridge, Canon Direct Print, Bubble Jet Direct or DPOF compatible printer:

• Print: (accessible only when the camera is connected to a printer) starts the printing process.
• Select Images and Quantity: serves to select the images to be printed, and the number of copies to make of each image.
• Select All Images: selects all the images currently on the memory card for printing.
• Clear All Selections: clears all selections and print orders.

• Print Settings: serves to choose the type of print to make (Index or Standard, or Both), whether or not the print should have the date imprinted on it, the file name, and whether or not all the Print Data should be automatically deleted once the images are printed.

A 32 MB Canon MMC (Multimedia) card is included with the PowerShot A640, but the camera is also compatible with SD (Secure Digital) and with SDHC (SD High Capacity) cards. The card slot is located next to the battery compartment, and is covered by the same latching door.

The capacity chart shown below provides still image and movie capacities for the 32 MB card included with the camera, and with an optional 1 GB SD card:

The PowerShot A640 runs off of 4 AA-size batteries, and is retailed with a set of non-rechargeable alkaline batteries. It offers greater autonomy, however, if rechargeable Ni-MH batteries are used.

A small flexible plastic door covers the external connections of the A640. Located on the upper right side of the camera, the door covers three jacks:

• The A/V (Audio/Video) jack is positioned at the top. The cable is included with the camera and serves to connect the A640 to a television, NTSC or PAL as determined in the Setup options (see the Interface and Software section of the review), or any other device equipped with an A/V port.
• Next is the USB port (USB 2.0 Hi-speed) which serves to connect the camera to either a computer or a printer.
• Last is the DC-IN jack (4.3 V) which is intended for use with the optional AC Adapter kit ACK600.