This month's Technical Report presents an overview of the advanced digital camera PowerShot G2 featuring a CCD with 4 million effective pixels and a 3x optical zoom lens (equivalent to 34 - 102 mm in 35mm film format).
Concept of development
The PowerShot G2 (see Photo 1) is a new model released this September as a successor to the PowerShot G1 (3 megapixel-class digital camera) launched last year. It was developed to achieve the following objectives:
Create a top-of-the-line compact digital camera with the "highest image quality and leading-edge functions"
|
Feature 1: High image quality
4 megapixel CCD (effective)
The PowerShot G2 uses a 1/1.8" CCD with 4 million effective pixels (4.10 million pixels in total), offering a high-quality image of up to 2,272 x 1,704 pixels, giving eminently usable image quality not only in A4-size prints but also in A3-size prints.
High-resolution, retractable 3x optical zoom lens
The PowerShot G2 has a high-resolution 7 – 21 mm 3x zoom lens (35mm equivalent: 34 – 102 mm), with a maximum aperture of f/2.0 (wide angle) - f/2.5 (telephoto). The lens consists of 8 elements in 7 groups. The high-refraction glass-molded aspherical elements and a cemented doublet lens are optimally arranged to achieve good aberration compensation, giving a high-resolution image throughout the entire range.
The use of an iris diaphragm for the aperture results in pictures with pleasing out-of-focus effects that only a large-aperture lens can achieve.
The closest shooting distance from the front of the lens is 6 cm in macro mode at wide-angle (82 x 60 mm image field).
Primary color filter and New digital signal processing IC for high-quality image processing The CCD on-chip filter is a primary color filter, instead of the complementary color filter used in the PowerShot G1. Although the primary color filter gives superior color reproduction, it has drawbacks in luminance signal to noise ratio (S/N) and resolution. To compensate, the PowerShot G2 incorporates the New digital signal processing IC, (see Photo 2) developed independently by Canon, in which all image processing functions are integrated on one chip. Signal processing in the new system runs with Canon’s unique algorithm optimized for the primary color filter, eliminating false colors as well as improving resolutio. |
|
Wide range of sensitivity (ISO equivalent speed) settings
Sensitivity is selectable from a range of settings [Auto/50/100/200/400 (ISO equivalent)] just like choosing film for a 35mm camera.
In the Auto mode, the PowerShot G2 automatically adjusts sensitivity to the optimum value within the range of ISO 50 - 100 equivalent.
Precision white balance with six preset positions and manual
Very faithful color reproduction is realized by dividing the screen into hundreds of thousands of areas; evaluating color based on the white balance data collected from each area; and computing the RGB values precisely with Canon’s proprietary technique.
Preset white balance has 6 modes: Daylight, Cloudy, Tungsten, Fluorescent, Flash, and the new Fluorescent H mode for daylight fluorescent lighting. It is also possible to customize the white balance by having the camera evaluate a white piece of paper.
RAW mode to maintain maximum image quality
The PowerShot G2 is equipped with the RAW mode, which stores image data as captured without any signal processing. Later when processing the image, the user can adjust the image quality parameters to obtain the desired image quality. The file size of a RAW-format image is only about a quarter the size of a TIFF-format file.
Feature 2: Advanced functions
Fifteen shooting modes
In addition to the 12 shooting modes (Program, Shutter priority, Aperture priority, Landscape, Portrait, Pan-focus and others) incorporated into the PowerShot G1, new “color effect” positions are provided. The color effect positions are: vivid color, neutral color, sepia, and black & white (Table 1).
|
Complete manual shooting functions
As with the PowerShot G1, the PowerShot G2 is fully equipped with manual shooting functions, such as manual focus, manual exposure control, and manual white balance.
The manual focus function, in particular, has been made much easier to use by displaying a distance guide in the MF indicator on the LCD monitor, and by enlarging the center of the image (or the area around the selected AF frame) while the manual focus function is being used.
Slow shutter speeds of up to 15 seconds extend the shooting range beyond the auto range.
| AF system with three selectable focusing points
Like the PowerShot G1, the PowerShot G2 allows switching of the AF mode between Continuous AF and Single AF. It is now possible to select among the three AF ranging points (center, left, or right, see Photo 3), enabling the user to focus on an off-center subject without difficulty. |
|
Three light metering modes
The PowerShot G2 provides three light metering modes:
(1) Evaluation metering
(2) Center-weighted averaging metering
(3) Spot metering.
With the evaluation metering mode, the entire image is divided into blocks. Based on the state of exposure of each block, the camera evaluates complex lighting factors, such as brightness, background, and back or front lighting, to calculate the optimum exposure. The center-weighted averaging metering method measures light over the entire image, with emphasis on the center, weighting the sensitivity according to proximity to the center of the image. When the spot metering is selected, either the center or one of the outer AF frames can be used.
High-speed continuous shooting
In addition to the existing continuous shooting mode, the PowerShot G2 also offers the new "high speed" mode. In this mode, the total number of images that can be shot continuously is fewer than with the "normal" mode, but shooting at 2.5 images/second is possible (1.5 images/second in normal mode). Five pictures in the high speed mode and nine in the normal mode can be shot when Large/Fine mode is selected. When Small/Fine mode is selected, 30 pictures in the high speed mode and 64 pictures in the normal mode can be shot, best among 4-megapixel class compact digital cameras.
Digital zoom with continuous variation of view angle
The PowerShot G2 incorporates the digital zoom system introduced into the IXY DIGITAL 200/300 and the PowerShot A20/A10, in place of the digital teleconverter function used in the PowerShot G1. This system provides continuous zoom up to approximately 11x in combination with the optical zoom.
AE lock / FE lock
The PowerShot G2 offers AE lock / FE lock as in the PowerShot G1, enabling changing the composition of the image without changing the exposure.
Furthermore, the camera incorporates the program shift function that allows the user to freely change the shutter speed / aperture combination while retaining the same exposure.
| Histogram display of playback image The PowerShot G2 is capable of displaying the histogram of the image (see Fig. 1) during playback. This function allows the user to check the distribution of brightness in the image and the overall exposure of each photo. If the image includes any washed-out areas, the histogram flashes as a warning. |
|
Built-in flash with five different types of control
AEB (Auto Exposure Bracketing) shooting is possible
Compatible with large-capacity CompactFlash (CF) card (Type II)
Real-image optical zoom viewfinder
Magnified playback (approximately 3x/6x)
Compatible with the USB Interface
Switching between worldwide video systems (NTSC/PAL)
Feature 3: Comfortable operation
Design for optimal handling
The entire camera makes extensive use of curved surfaces. Especially the rear of the camera, where the operation controls are located, presents an organic continuation of the flexible curved surface, absorbing protrusions and depressions in the surface while improving the grip of the camera and its ease of operation.
The camera strap is now attached at both ends, instead of only one end of the PowerShot G1, for safe carrying and quick response.
Vari-angle LCD monitor
The PowerShot G2 was designed with a Vari-angle LCD monitor (100% picture coverage) which rotates freely to secure easy shooting from any angle such as high-angle, low-angle and photographing the photographer.
The optical viewfinder has eyesight correction with a range of -3 to +1 diopter.
Power-saving design recording 1,000 images on a single charge
The PowerShot G2 conserves energy with the New digital signal processing IC, a low-power design, and by using multiple power supplies for circuits with different requirements. When the LCD monitor is OFF, the PowerShot G2 can capture as many as 1,000 frames on a single charge of the rechargeable batteries (approximately 25% increase over the PowerShot G1).
Direct print mode
The PowerShot G2’s direct print mode enables the users to print out high-quality images by simply connecting the camera to the Card Photo Printer CP-10 with an interface cable. When connected, the camera controls the printer. A "Trimming" mode is available to print any portion of the image in enlarged form.
Instant switching between shooting and playback
Pseudo shutter sound like a 35mm camera
Feature 4: Comprehensive application programs and extensive system accessories
Comprehensive package of application programs
Software programs to manipulate images using a computer come with the PowerShot G2, such as ZoomBrowser EX/ImageBrowser EX for image import and management, retouching, automatic image layout, automatic attaching images to e-mails, as well as PhotoRecord for automatic layout and print of multiple images and PhotoStitch for creating panoramic pictures (see Photo 4).
| Extensive system accessories Optional accessories, which are sold separately, include the 0.8x wide converter (WC-DC58), d the 1.5x teleconverter (TC-DC58) and the Close-up lens 250D with which you can shoot the image field as small as 50 x 38 mm at maximum telephoto. In addition to being compatible with the EX Speedlites for EOS cameras, the PowerShot G2 also can be used with the Macro Ring Lite MR-14EX (see Photo 5). |
|
This issue of the Technical Report introduces the PowerShot G2. Table 2 compares the major specifications between the PowerShot G1 and the PowerShot G2, while Fig. 2 shows the names of exterior parts of the PowerShot G2.
Table 2 Comparison of major specifications between PowerShot G2/G1
| PowerShot G2 | PowerShot G1 | ||
| Image sensor | 4.13 megapixel (total) 1/1.8 in. CCD (effective pixel: 3.95 megapixel) |
3.34 megapixel (total), 1/1.8 in. CCD |
|
| Filter array | Primary color filter | Complementary | |
| Lens | 7(W) - 21(T) mm (35mm film equivalent: 34 – 102 mm) f/2.0(W) - 2.5(T) |
 |
|
| Optical zoom | 3x | |
|
| Digital zoom | 3.6x | Digital tele-converter (2x / 4x) |
|
| Optical viewfinder | Real-image optical zoom viewfinder | |
|
| LCD monitor | 1.8 in. low-temperature polycrystalline silicon TFT color | |
|
| Autofocus method | Switchable focusing points (Center or 3 selectable positions), TTL-AF (single / continuous) |
1 focusing point, TTL-AF (single / continuous) |
|
| Focusing range (normal) | 70 cm - infinity | |
|
| Focusing range (macro) (from lens barrel tip) |
W | 6 – 70 cm | |
| T | 20 – 70 cm | |
|
| Shutter type | Mechanical + Electronic | |
|
| Shutter speeds | 15 - 1/1,000 sec. | 8 - 1/1,000 sec. | |
| Light metering method | Evaluative / Center-weighted averaging / Spot (Center or AF Point) | Center-weighted averaging / Spot | |
| Exposure control method | Program AE / Shutter-priority AE / Aperture-priority AE / Manual | |
|
| Exposure compensation | ±2.0 EV (in 1/3-stop increments) | |
|
| Sensitivity | ISO 50 - 400 equivalent | |
|
| Flash range | W | 0.7 – 4.5 m | |
| T | 0.7 – 3.6 m | |
|
| White balance | TTL auto / Pre-set (6 positions) / Custom | TTL auto / Pre-set (5 positions) / Custom |
|
| Shooting modes | Auto / Creative zone / Image zone (additional of “Color effects”) |
(except “Color effects”) |
|
| Continuous shooting mode | High speed (approx. 2.5 image/sec.) / Normal (approx. 1.5 image/sec.) |
Normal | |
| Storage media | CompactFlash card (Type I and II) | |
|
| File format | DCF (DPOF-compliant) | |
|
| Image recording format | (SF / F / N) x (L / M1 / M2 / S)+RAW (13 combinations) |
(SF / F / N) x (L / M / S)+RAW (10 combinations) |
|
| Number of recording pixels |
L | 2,272 x 1,704 | 2,048 x 1,536 |
| M1 | 1,600 x 1,200 | 1,024 x 768 | |
| M2 | 1,024 x 768 | ||
| S | 640 x 480 | |
|
| Direct print (CP-10) |  |
 |
|
| Interfaces | USB / Video/Audio Output | USB / RS-232C / Video/Audio Output |
|
| Power sources | Rechargeable Lithium-ion battery (BP-511)(BP-512) / AC adapter | Rechargeable Lithium-ion battery (BP-511) / AC adapter | |
| Dimensions (W x H x D) |
120.9 x 76.6 x 63.8 mm | 119.7 x 76.8 x 63.8 mm | |
| Weight (camera body only) |
Approx. 425 g | Approx. 420 g | |
Fig.2 Nomenclature
