Canon EOS Rebel T1i EOS System Brochure 2010 - Page 14

Taken with EF 100-400mm f/4.5-5.6L IS USM Optical Image Stabilizer Mode 2 The standard settings of the Optical Image Stabilizer are set so that it is most effective when photographing stationary subjects. However when panning with a moving subject is attempted (tracking of the subject horizontally or vertically), the shake-correction of the OIS may inadvertently over-compensate and interfere with framing. To help resolve this, Canon developed Optical Image Stabilizer Mode 2. In this mode, if you move the lens to follow a subject for a predetermined time, the Optical Image Stabilizer does not correct for the intentional panning while continuing to correct any camera shake that's perpendicular to the panning motion. The result is a virtually smooth viewfinder image as you follow the moving subject. Hybrid Image Stabilizer During normal shooting situations, sudden camera movement in rotational camera angle can cause significant image blur. During macro or close-up photography however, the image blur caused by linear camera shake-when the camera moves parallel to the subject-is more pronounced. Optical Image Stabilizer is optimized to counteract rotational or angular camera shake and works well for most camera shooting situations. To help compensate for linear camera shake, a new acceleration sensor determines the amount of shift-based camera movement. The new Canon Hybrid Image Stabilizer technology employs a highly sophisticated algorithm that combines the feedback of both the acceleration sensor Linear Camera Shake and angular velocity sensor (found in current OIS technology) and moves the image stabilizer lens elements, effectively compensating for both rotational and linear camera shake. Hybrid IS dramatically enhances the effects of Optical Image Stabilizer especially during macro shooting, which may be difficult for conventional image stabilization technologies. 28 EF LENSES Diffractive Optics Canon's use of diffractive optics (DO) results in high-performance lenses that are much smaller and lighter than traditional designs. Canon's unique multilayer diffractive elements are constructed by bonding diffractive coatings to the surfaces of two or more lens elements. These elements are then combined to form a single multilayer DO element. Conventional glass lens elements disperse incoming light, causing chromatic aberration. The DO element's dispersion characteristics are designed to cancel chromatic aberrations at various wavelengths when combined with conventional glass optics. This technology results in smaller lenses with no compromise in image quality. Canon has also developed a new triple-layer type DO lens that uses an advanced diffractive grating to deliver excellent performance, with superb control of color fringing. This configuration is ideal for zoom lens optics and provides significant EF 400mm f/4 IS DO USM •f/4 • 1/1250 sec. Refractive Optical Element Chromatic aberrations Refractive Optical Element and Multi-Layer Diffractive Optical Element Combined Image formation in the blue, green and red wavelength order Multi-Layer Diffractive Optical Element Chromatic aberrations reversed from that of a refractive optical element Chromatic aberration canceled out Image formation in the red, green and blue wavelength order Red Green Blue Correction of Chromatic Abberation by the Multi-Layer Diffractive Optical Element. reductions in size. A good example is the EF 70-300mm f/4.5-5.6 DO IS USM lens, which is 28 percent shorter than the EF 70-300mm f/4-5.6 IS USM lens. Ultrasonic Motor Canon developed the world's first lens-based Ultrasonic Motor (USM) to power the lens autofocus mechanism. Instead of large noisy drive trains powered by conventional motors, Canon USM lenses employ the minute electronic vibrations created by piezoelectric ceramic elements. The focusing action of the lens is fast and quiet, with virtually instantaneous stops and starts. USM lenses also draw minimal power from the camera, ensuring longer battery life. Canon makes two types of Ultrasonic Motor lenses. Ring-type USM lenses, found in large aperture and supertelephoto designs, permit manual focusing without first switching out of the Ring-type USM auto mode. Micro USM designs bring the performance benefits of Canon's USM technology to a wide assortment of affordable EF lenses. Micro USM L-series Lenses Most highly regarded among professional photographers, Canon L-series lenses are distinguished by a bold red ring around the outer barrel. What makes them truly distinctive, however, is their remarkable optical performance - the result of sophisticated Canon technologies, such as Ultralow Dispersion UD glass, Fluorite and Aspherical elements and Super Spectra Coating. Fluorite / UD Elements Reducing color fringing, or chromatic aberration, has been one of the great challenges in the design of telephoto lenses. L-series telephoto lenses - like the EF 70-200mm f/2.8 IS II USM and EF 300mm f/4L IS USM - employ Canon's Ultra-low Dispersion glass to minimize this effect, providing much improved contrast and sharpness. Even more effective at suppressing chromatic aberration Anomalous dispersion Glass Red Blue Red Blue Fluorite Comparison of optical characteristics between optical glass and Fluorite are Fluorite elements, used in high-end super-telephoto L-series lenses. Composed of crystallized calcium fluoride (CaF2), a single Fluorite element, although costly, has roughly the corrective power of two UD-glass elements, giving these L-series lenses their spectacular performance and relatively compact design. Aspherical Elements Wide-angle lenses and fast normal-focal-length lenses often suffer from spherical aberration. When the light rays coming through the center of the lens do not converge at the same point as light rays coming through the lens edge, the Spherical aberration of spherical lens. Convergence of parallel light rays by an Aspherical lens. image appears blurred because there is no sharp point of focus. Canon's Aspherical elements use a varying curved surface to ensure that the entire image plane appears focused. Aspherical optics also help to correct curvilinear distortion as one might find in ultra wide-angle lenses. Canon designs aspherical elements with extremely precise variable curvature of one or both sides, making possible lighter, more compact lenses. Subwavelength Structure Coating SWC is a new proprietary lens coating that helps control ghost and flare to a far greater degree than with earlier coating technologies. Utilizing SWC technology on large-curvature lens elements that are mainly found in wide-angle lenses, will significantly minimize the occurrence of ghosting and flare caused by reflected light in environments that have posed problems. SWC is used on the latest Canon wide angle lens, EF 24mm f/1.4L II USM. EF 24mm f/1.4L II USM •f/6.3 •13 sec. Focus Preset Focus Preset enables you to program a focusing distance in the camera's memory. Normal picture taking and focusing are unaffected by preset distances. For example, at a soccer game, you Focus Preset the goal area. Shoot normally elsewhere on the field, but once the action moves toward the goal, the user can instantly return to the preset distance by turning a ring on the lens. 29