Technologies and features common to canon dSLRs

Regardless of which dSLR you have or are considering, Canon has a long track record of employing consistent technologies within their dSLR lineup. Since digital photography came into its own, a defining characteristic of the progression of the industry has been the gradual addition of more and more high-end (professional) functionality to consumer models. The EOS Digital Rebel XT and the Digital Rebel XTi offer shooting modes, exposure features, speeds, and more importantly results that rival their more expensive counterparts, as evidenced in 2-4. Certainly this trend of adding advanced features at consumer-level prices is an advantage for photography enthusiasts.

Canon's Digital Rebel XTi is quite capable of producing professional results under demanding shooting situations. Taken with a Canon 24-105mm L lens, ISO 100, f/5.6 at 1/4000 second.

But more importantly, as Canon’s ongoing research and development continues to refine camera features, Canon has progressively applied new and improved technologies throughout its camera lineup. As a result, photographers can rely on a consistently high level of quality as well as overall similarity of features and functionality from one Canon dSLR camera to another. And as a result, as photographers move from one camera to another, the learning curve is lower, allowing quick integration of the new camera into the system.

In addition, functionality that is common to multiple camera models is a boon for photographers who use more than one camera body. For example, Canon’s Picture Style feature, a set of preprogrammed and customizable settings that set the color tone, contrast, saturation, and sharpness of images, means that photographers can set up multiple cameras to produce consistent image “looks” across all cameras. And with consistent image results, postcapture editing becomes consistently more standardized, which increases efficiency.

While the evolution of digital technology means that some newer cameras offer technologies that previous cameras could not, certain core technologies are common to all Canon dSLR cameras, as explained in the next sections.


There are two primary types of digital image sensors: CCD, or charge-coupled device, and CMOS, or complementary metal-oxide semiconductor. Both are types of chip technology; Canon uses CMOS sensors in their cameras. Both types of sensors absorb light and convert it into digital information (electrons), but accomplish the task differently in terms of how and where they process the light-to-electron conversion.

Canon is one of the few camera manufacturers that use CMOS sensors and that produce and market full-frame, 35mm-size image sensors — sensors that are used in the EOS-1Ds Mark III and the EOS 5D. Canon is also one of the only companies that design and manufacturer its sensors in-house for all of its dSLRs. This marriage of the camera and sensor technology has been instrumental in making Canon the leader in dSLR technology.

Here are current advantages and limitations of each type of sensor.

  • CCD sensors. CCDs are the oldest image sensor technology, proven in image scanners and other optical devices; in general, they offer low image noise but they have inherent limits. The sequential processing of electrical charges limits the speed at which CCDs can process images. Also, the voltages needed to initiate the relay of charges across the CCD require more power than CMOS sensors. This demand for more power at longer shutter speeds creates more heat and, subsequently, more digital noise in the image. In addition, CCD-based camera batteries must be larger and they require longer recharge times.
  • CMOS sensors. CMOS sensors work in a similar fashion to CCD sensors but use less power and can process images much more quickly due to differences in design. While the CMOS architecture offers the advantages of low power consumption and high speed, the technology has inherent disadvantages in that it produces more noise. Canon has, over the course of several years, addressed this problem with their extensive in-house technology. The result: Canon’s CMOS sensors now provide both faster operation and less digital noise.


After image capture but prior to the recording stage, camera image processing determines how the signals from the sensor are translated into a viewable image. In Canon dSLRs, this function is performed by the DIGIC Image Processor chip.

The DIGIC II Image Processor provides quick but high-quality image processing, as well as enhanced color and white balance, and optimized camera performance — all with relatively low power requirements. Newer Canon dSLRs feature the new DIGIC III Image Processor with even better performance.


All of Canon’s dSLR cameras offer the option of recording both a JPEG and a RAW image simultaneously. Simultaneous RAW+JPEG recording offers the best of both worlds — a preprocessed JPEG digital proof to quickly preview your shots, and the highest quality RAW images for those of you desiring the quality of the RAW format. This also translates into a considerable timesaver if you don’t want to convert RAW images to JPEGs before posting or e-mailing them.

New to the EOS 1D Mark III, the EOS 1Ds Mark III, and the EOS 40D is the sRAW format, with the s standing for small. Instead of RAW photography always producing full-sized files that occupy lots of storage space, these smaller files are great options if you like the advantages of RAW but don’t need the full resolution of a full-sized RAW file; they are about one-quarter the size.

There are of course situations where you may only need small JPEGs, such as for e-mail, the Web, or other online applications. Also you may need the extra frame rate provided when shooting just JPEGs (smaller files mean faster write time). In these cases just select which JPEG you need.


Canon dSLRs also offer the ability for photographers to modify image settings, including contrast, color tone, saturation, and sharpness. The controls for adjusting these settings vary by camera. On the EOS Digital Rebel XT, the settings are called Parameters.

On the EOS-1D Mark III, EOS-1Ds Mark III, EOS 5D, EOS 40D, and the EOS Digital Rebel XTi, the settings are called Picture Styles. In either case, they include a group of programmed settings that modify the look of pictures and offer the ability to modify the programmed settings as well as create user-defined settings. You can see an example of using the Portrait Picture Style in figure 2-5. Picture Styles and Parameters are discussed in more detail later in the chapter.

The Portrait Picture Style was applied to this image to enhance the portrait look. Taken with an EOS-1Ds Mark II, Canon 24-70mm L lens, ISO 100, f/10 at 1/125 second.


From the outset of introducing its mainstream dSLRs, Canon provided the ability for photographers to customize camera functionality by modifying custom functions via the camera menu. This feature allows you to modify the camera to suit your needs. For example, you can change the function of the cross-keys of the EOS Digital Rebel XT or set a Custom Function on the EOS-1Ds Mark III to turn on safety shifting in Shutter-or Aperture-priority AE modes. Custom functions are a boon to all photographers, and especially to those with specific shooting preferences, such as having the ability to set autofocus (AF) point selection on the EOS-1Ds Mark III. The number of custom functions varies by camera model, ranging from 9 on the Digital Rebel XT to 57 on the EOS-1Ds Mark III. Knowing the potential complexity of the Custom Function options, particularly on the EOS-1Ds Mark III, Canon gives you an option to set Custom Functions back to their default settings. On cameras with automatic modes, modifications to Custom Functions operate in all except Full Auto mode. Some of the more useful Custom Functions are explained later in the chapter.


Canon’s Picture Style feature had its beginnings as the Parameters feature in the EOS Digital Rebel cameras. Like Picture Styles, Parameters provided a set of preprogrammed and user-definable settings for contrast, color tone, saturation, and sharpening to achieve a look, much like different films offered different looks. Currently, the EOS Digital Rebel XT still uses Parameters, while the EOS Digital Rebel XTi (400D), the EOS 5D, the EOS 40D, the EOS 30D, and the EOS-1D Mark III and EOS-1Ds Mark III offer the newer Picture Style feature.

Category: Photography System

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