Category: Science of Lenses

Without a lens, a camera is little more than a light-absorbing machine incapable of producing anything really useful. In comparison to a camera’s extensive and complex technology and mechanics, you might think a lens is relatively simple; however, lenses encompass a tremendous history of technological and scientific research and application that dates back to the first telescopes and microscopes invented in the 1600s.

This chapter is all about the science and technology behind how lenses work, and why they work so well. Having a basic understanding of these ideas can help you as you expand your photography skills and select new and/or better lenses for your collection.

Evaluating color and contrast

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 [...]

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Diffraction

Diffraction

When light travels through lens elements and through your aperture opening, some small amounts of it are diffracted, meaning dispersed and essentially no longer a part of your image. Usually the amount of light diffracted is negligible under normal conditions; however, it can occur when you are shooting with an exceptionally small aperture setting, such [...]

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False colors

False colors

False colors can occur when photographing subjects with detailed, high-contrast geometric patterns — whether it is clothing or the pattern on an object in a product shot. Your camera’s image processor can misinterpret the signals from the image sensor and add colors to the image that are not actually there. False colors are not a [...]

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Moire patterns

Have you ever seen a distracting pattern on a person’s jacket or shirt when watching television? This effect, known as a moire pattern, is caused by geometric elements of a subject and image sensor conflicting with one another. It’s one reason that portrait photographers generally advise clients not to wear geometric patterns in clothing when [...]

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Chromatic aberration

Chromatic aberration

While not very common with Canon’s current, superior lens technology, some lenses, such as very wide-angle and long telephoto lenses, can occasionally suffer from an effect known as chromatic aberration, or color fringing. This is when the lens elements do not converge the colors of refracted light precisely onto the focal plane (see figure 5-4), [...]

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Lens flare

Lens flare

Lens flare is the result of unwanted light entering the lens and hitting the image sensor. How the effect occurs depends upon various factors such as the number of internal lens components, lens focal length, aperture size and width, and the type of light source and its brightness (such as the sun, a spotlight, etc.). [...]

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Ghosting

Ghosting

Pointing a camera and lens toward a bright light of any kind can produce ghosting, which has two prominent features: an area of overexposure that is completely white and a part of the image that is streaked and patterned. It is caused by strong light reflecting from the image sensor back to the lens of [...]

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What is an Modulation Transfer Function chart?

What is an Modulation Transfer Function 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. [...]

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What makes a lens good?

What makes a lens good?

What makes a good lens can be argued on a scientific basis or according to aesthetic considerations. Most people want a lens that produces a tack-sharp image with great color rendition for superior image quality. Certainly, how the lens handles mechanically is also important; it has to function as the photographer’s instrument and be able [...]

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Focal length and aperture effects

Focal length and aperture effects

While some photography technologies relate only to your camera’s internal operation, and knowing them won’t necessarily make you a better photographer, understanding some others can have a direct impact on your compositional skills and your ability to control your camera more completely. FOCAL LENGTH AND IMAGES Knowing the relative behavior of lenses, how focal length [...]

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Canon lens technologies

Canon lens technologies

Canon’s lens technology leads the industry in producing supersharp, high-resolution pictures. Optical engineering plays a fundamental role in the design of a dSLR camera, and consequently, lenses must also be engineered to even greater levels of precision. Through the development and use of such technologies as diffractive optics, fully electronic mounts, and image stabilization, just [...]

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How the lens communicates with the camera

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 [...]

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How lenses work

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 [...]

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