Practically all digital Canon compact cameras (and all of the newer camera models) are equipped with a zoom lens, allowing for an optical zoom range from 1:3 to 1:20+. The optical zoom can be extended via an optional digital zoom. All zoom lenses are equipped with a macro function, which again can be extended with a digital macro. Digital zoom and digital macro come at a cost, however: they reduce image resolution because only a part of the sensor is used for the final image.
Most Canon cameras are equipped with an optical i mage stabilizer; usually, these cameras carry the suffix “IS” in their name. “Optical” means that a lens element is moved to counteract camera shake. With this technique, it is possible to increase exposure times by a factor of 2-16 (1-4 f-stops) when shooting without a tripod. An image stabilizer is a very useful feature, especially for telephoto shots and for shooting in low light conditions.
Most Canon cameras use CCD (charge coupled device) type sensors; only a few use CMOS type sensors. Smaller models have sensors with a diameter of 1/2.5 inch (10 mm), while larger models have sensors with a diameter of 1/1.7 inch (14.9 mm). The focal length conversion factors are 6.2 and 4.6 respectively, compared to the 35mm format.
For most Canon cameras, the resulting image is delivered in the form of a JPEG file with selectable resolutions and formats, and selectable compression ratios. Top-range cameras offer an option to deliver the RAW sensor data, too. Actually, the prime motivation behind the development of the Canon Hacker’s Development Kit was to enable smaller, low-cost cameras to deliver sensor data in RAW format. It should be mentioned that digital zoom and digital macro do not work with RAW format; the format delivers the pure sensor data without any post-processing.
For the smaller models—especially the Digital Elph (Ixus) series—the shutter mechanism consists of a simple mechanical shutter plus an electronic shutter. Because the circuitry for the electronic shutter requires some space on the sensor chip, less sensor area is left for the light-sensitive parts — resulting in a less than optimal signal-to-noise ratio compared to a DSLR. Therefore, the top-of-the-range Powershot models, such as the G-series, use a mechanical shutter in order not to sacrifice valuable sensor real estate.
Similarly, the lenses of the low-cost cameras are not equipped with a diaphragm but rather with an ND (neutral density) filter that is switched on when the scene becomes too bright. Because the lens is always used at full aperture, it is not possible to increase the depth of sharpness (DOF) by stopping down with these cameras. Variations in brightness and shutter speed are compensated for by the ND filter and by changing the sensor’s sensitivity (ISO speed). Higher-priced cameras are equipped with a traditional diaphragm.
All Canon cameras are, of course, equipped with autofocus (AF) and automatic exposure (AE) control. Newer models even have face detection. Only the top-range models allow for manual control of focus, shutter speed, aperture, and ISO. With the CHDK, manual control of focus and exposure is achieved for all models—within the physical limits of the camera, of course.
All Canon cameras are equipped with an internal flash unit. Some larger cameras offer the option of connecting an external flash as well. Unfortunately, not all cameras allow fine-tuned manual control of the flash power. As a result, flash images can often look unnatural and flat. In many cases, the flash is too bright. The CHDK allows a manual flash on all models with three different power settings, resulting in more natural-looking flash images.
All Canon cameras are equipped with a video function, in some cases an HD video function. Because the camera’s image sensor has a much higher resolution than a video frame, digital zoom (Digital Converter) can be utilized to a certain degree for video shots without losing quality. In most cases, the optical zoom is disabled during video shooting, as the zoom motor’s noise would ruin the soundtrack. With the Canon Hacker’s Development Kit, this behavior can be overridden (for some cameras) and the optical zoom can be used while shooting video. Some editing will be required, however, for the soundtrack.
The built-in audio facility (microphone and audio digitizer) that is used for the video soundtrack can be used for photos, too. Voice notes can be attached to photos, or the camera can be utilized as a dictating machine.
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