Technology Used in Interchangeable Lenses
Canon's interchangeable lenses for interchangeable-lens digital cameras, such as digital SLR (single-lens reflex) and digital cinema cameras, are realized through advanced proprietary technologies and know-how. This page introduces some of the technologies incorporated in the EF lens lineup.
SWC (Subwavelength Structure Coating)
Lens Coating Technology Created by Nanotechnology
The reflection of light from the lens surface causes flare and ghosting. In the past, the surface was coated with a thin film to control reflected light, but it could not be sufficiently controlled in some cases depending on the angle of incident light.
SWC developed by Canon is a new type of technology for preventing reflection by using an array of countless wedge-shaped nanostructures smaller than the wavelength of visible light arranged on the lens surface to control the reflection of light. As there is a smooth transition between the refractive indexes of glass and air, it is possible to eliminate the boundary between substantially different refractive indexes, which enables significant control over the occurrence of reflected light. It is also very effective with light that has a large angle of incidence, which could not be controlled using conventional coating.
A Compact, Reduced-Weight Telephoto Lens
The Diffractive Optics (DO) lens for SLR cameras is designed to utilize the opposing chromatic dispersion patterns of diffractive and refractive optical systems built into the lens. Canon has applied optical principles to substantially reduce both the size and weight of this telephoto lens for SLR cameras. (EF400mm f/4 DO IS USM)
Diffraction gratings are bonded next to each other in a close-proximity arrangement on the surfaces of the elements inside the DO lens system. Adjacent gratings are separated by no more than a few microns. Canon has created the world's first camera lens of this type.
Next, the company conducted an even more thorough study of the materials and shape of the diffraction gratings, developing a three-layer DO lens that utilizes three diffractive optical elements. Incorporating the three-layer DO lens into the EF70-300mm f/4.5-5.6 DO IS USM zoom lens, Canon also successfully reduced the size of telephoto zoom lenses.
High definition video can be viewed in the CANON VIDEO SQUARE.
Hybrid IS (Image Stabilizer) to Simultaneously Correct for Angle Camera Shake and Shift Camera Shake
Even a small shake of the hand while the shutter is open can result in image blur. Hand shake causes lens movement around the camera, resulting in either camera rotation around the optical axis or camera movement in the lateral direction. Angle camera shake (Fig. 1), which causes lens movement around the camera, can be corrected by the Image Stabilizer (IS), the conventional mechanism for compensating for hand shake. IS, however, is less effective at correcting blur caused by parallel camera movement, known as shift camera shake (Fig. 2), when taking close-up shots, such as during macro photography.
For more dependable correction against angle camera shake and shift camera shake, Canon now incorporates an acceleration sensor to detect motion in the parallel direction in addition to the existing vibration gyro (angular velocity sensor) to detect angular motion. A new anti-shake algorithm calculates the optimal hand shake correction based on camera movement detected three-dimensionally by the two sensors. The Hybrid IS technology is the world's first to correct both angle and shift camera shake in interchangeable lenses for SLR cameras.*1
- *1 As of July 17, 2009, based on a Canon survey
Silent and Smooth AF
STM Delivers Silent and Smooth Movie Servo AF Performance
A lens's operating noise during auto-focusing can be obtrusive, especially when recording movie shooting. That is why Canon employs an STM (stepping motor) in its EF lenses that minimizes operating noise.
Designed to operate in synchronization with pulsed power, the STM rotates a single step per pulse of electrical signal. Accordingly, STMs, which are also known as pulse motors, offer superior response and controllability at start and stop. Their simple mechanical structure also contributes to smooth, low-noise lens operation and smaller lens sizes.
The lead-screw type STM, employed in such as the EF-S18-135mm f/3.5-5.6 IS STM and EF-M18-55mm f/3.5-5.6 IS STM, delivers exceptionally silent and smooth operation.