Diffractive Optics

Lenses do not form perfect images, and there is always some degree of distortion or aberration introduced by the lens that causes the image to be an imperfect replica of the object. Careful design of the lens system for a particular application ensures that the aberration or distortion is minimized. Telephoto and super-telephoto lenses are especially susceptible to chromatic aberration, which is an optical color defect. Diffractive optics (DO) technology, which was designed to correct these...

Dust And Waterresistant Construction

Like the Mark III camera series, certain longer-range Canon lenses are constructed to be dust- and water-resistant. Specifically, the EF300mm f 2.8L USM, EF 400mm f 2.8L IS USM, EF 500mm f 4L IS USM, and EF 600mm f 4L IS USM lenses all feature rubber linings for key points where unwanted elements can enter the camera. Moving parts, such as the focusing ring and switches, are sealed, as are switch panels, exterior seams, and drop-in filter compartments. You might notice that the extra rubber...

Assignment

You may just be getting acclimated to your new Canon dSLR, or you may have had it for a few years and are just now ready to expand your gear collection. Regardless of which category or place that you fall, you no doubt have some combination of equipment that is your favorite. Show your love to the other readers by taking a photo using your favored gear and post it on the Web site to share with other readers. Who knows Maybe you will find a kindred spirit My favorite Canon combo is the EF...

The Canon Eos D

The EOS 5D (see 2-8) was an instant hit upon its release and it is no wonder, considering that it offers a full-frame CMOS sensor with 12.8 megapixels and currently sells for less than 3,000. It has become a fast favorite of many professional photographers, due to the high resolution and lighter weight of previous full-frame dSLRs. Price has also contributed to its popularity. As I mentioned previously, the overriding difference aside from higher resolution is the build quality. The Mark III is...

Evaluating Color And Contrast

Understanding and judging color and contrast in your images are essential to producing good photography. Your lenses are where color and contrast begin and, to some extent, where they are controlled as they are processed as an exposure before being converted into a digital image. Histograms are available for you to use as an evaluative tool on your camera's LCD, as well as later in software image-editing applications. These graphs, which give you information about shadows, highlights, midtones,...

Floating System

Lesser-quality lenses often produce acceptable results when focused in a mid-range, common focusing distances. However, they can and do produce image aberrations at extreme focal ranges especially the closer ones. This is generally the result of inaccuracies between lens elements that work well when positioned together for common ranges, but are less accurate when at their least-common configurations. Canon lenses employ a floating system of optical elements, which automatically adjusts gaps...

How The Lens Communicates With The Camera

Most modern lenses have the ability to communicate electronically with the camera. All Canon EF mount lenses contain a microprocessor within the lens providing a set of information to the camera. When you turn on an EOS camera, the camera and lens communicate. The camera knows the focal length of the lens, and if it is a zoom lens, it knows the actual current zoom setting, the maximum and minimum aperture, and a host of other factors. When the camera is activated, all this information is...

Setting Picture Styles Or Parameters

Parameters and Picture Styles allow you to set certain guidelines for how your images are processed by the camera. You can select from numerous styles or looks, depending on the effect you are after. For example, on the EOS Digital Rebel XT, Parameters are available in automatic shooting modes, and they include two preset parameters for either standard color and sharpness or more subdued color, a Black and White (B W) parameter, and three user-definable sets of parameters. On newer cameras,...

Additional Canon System Components

The most expensive components of a photography system are camera bodies and lenses, but a variety of accessories increase your creative options. Additional components include Canon Softmat filters and close-up lenses, teleconvertors to increase the effective focal length of lenses, Speedlite flashes, circular polarizing and haze filters, a variety of remote control accessories, a wireless file transmitter, a data verification kit, a variety of eyecups and extenders, angle finders, and focusing...

Evaluating Depth of Field

One of the best ways to really learn about DOF is to find an interesting subject, preferably one that is stationary, and photograph it using any one of your lenses. Take one shot at the widest possible aperture (for example, one at f 2.8, one at a mid-point aperture such as f 8, and another at f 16), keeping your camera and your distance from the image constant. Notice how the DOF varies in each of the three images. Which one do you like best and why Post your results to the Web site. I took...

Building The Backbone Of Your System

You should treat your camera system as you would a good-quality audio system Purchase great speakers and work back toward the amplifier. As you upgrade other equipment, the system will continue to get better if you start with inferior-quality speakers, the other components don't matter as much. Consider lenses in the same manner Concentrate on getting good glass before you purchase a top-of-the-line digital SLR camera. Lenses range in focal length from fisheye to super-telephoto and are usually...

Autofocus Systems

Autofocus (AF) systems rely on one or more sensors to determine correct focus. Some AF systems rely on a single sensor, while others use an array of sensors. Most modern digital SLR cameras use through-the-lens optical AF sensors, which also function as light meters. The speed and accuracy of through-the-lens optical autofocusing is now more precise than what you can achieve manually with an ordinary viewfinder. Autofocus accuracy within a third of the depth of field at the widest aperture of...

What Resolution Is Right For

While most photographers focus on the number of megapixels to gauge a camera's resolution, the actual resolution is more complex than the number of pixels on an image sensor. For example, the camera may not use all the pixels in the digital image some pixels may be used for other imaging tasks. Other factors come into play as well, such as sensor size and digital noise, which is the grainy quality of a low-light digital image. Sensor size must be a consideration in evaluating megapixel count....

Looking At The Canon Dslr Lineup

Lining up the Canon dSLR models on a camera store counter creates an impressive array of choices. If you put the lenses of your choice on each camera body, the lineup quickly becomes a photographer's ultimate toy store. Each camera presents a unique opportunity that satisfies the shooting needs, requirements, and credit limit of one or another photographer. This section gives you an overview of Canon's dSLRs, with insights that you're unlikely to learn while browsing at a camera store. In the...

How Lenses Work

The lens acts as the eye of your camera, and, like the human eye, some lenses focus better than others. Some are better at seeing distances others are better at reading fine print. Camera lenses are typically made of many individual polished glass elements. For the camera, the function is the same to focus light rays onto a light-sensitive surface, or in this case, a digital sensor. The better the lens does the job, the sharper your picture. The simplest type of lens is a single-element convex...

What Is An Mtf Chart

A Modulation Transfer Function MTF chart represents basically how a lens is evaluated. You can find these charts, for example, on the Canon Web site where lens descriptions are found simply go to the product page for one of the specific lenses, and in the overview section they generally present an MTF chart for it. These charts are created from data based on how well the lens transmits evenly spaced lines of black and white as measured precisely in line pairs per millimeter 10, 20, or 30 line...

What Difference Does Frame Rate Make

The frame rate of a camera is the speed at which images can be continuously recorded and saved. Frame rate is governed by several factors, including the resolution number of pixels , the buffer size, the speed of the image processor, and the write speed of your memory card. Obviously, higher-resolution cameras such as the 5D and the IDs Mark III have more information to transfer, which takes more time. The buffer size in a digital camera is basically the amount of memory or storage the camera...