In response to demands of photographers, this standard zoom lens is designed with Canons Optical Image Stabilizer technology while retaining the compactness and lightness of previous models. Its stabilization allows sharp hand-held shots at shutter speeds up to four stops slower than otherwise possible. It consists of 11 elements in 9 groups and uses an Aspherical lens element to correct aberration for excellent image quality throughout the zoom range and a circular aperture for exquisite rendering of out-of-focus backgrounds. Without a lot of size, weight or cost, this lens expands picture-taking possibilities any time slow shutter speeds are needed.
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EF-S18-55mm f/3.5-5.6 IS
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| Photo 1: EF-S 18–55mm f/3.5-5.6 IS | ||||||
Development objectives The EF-S 18-55mm f/3.5-5.6 IS (Photo 1) is a standard zoom lens developed specifically for the EOS 40D and other APS-C sensor EOS Digital series cameras. The lens combines light weight, small size and superb cost performance with image stabilization. The primary aims of the lens's development are outlined below. Feature 1 : Image stabilization in a lightweight, and compact body Canon's engineers have been able to fit an image stabilizer unit in this lens while keeping it equivalent in size and weight to the non-IS EF-S 18-55mm f/3.5-5.6 II USM. A number of innovations made this possible including the compact zoom optics, the new smaller image stabilizer unit, the mechanical layout optimized to fit in very limited space, and the miniaturized electronic circuit board. | ||||||
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| Figure 1: Construction of the EF-S 18-55mm f/3.5-5.6 IS | ||||||
Feature 2 : Outstanding optical performance The goal of the lens's optical design was to retain the acclaimed quality of the optics developed for the EF-S 18-55mm f/3.5-5.6 II USM while adding a new image stabilization mechanism. The inclusion of a precision aspherical element in the design provides excellent aberration correction, particularly of spherical aberrations, and ensures top image quality at all focal lengths (figures 2 and 3). The focal length range is equivalent to 29-88mm in 35mm-film format. | ||||||
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| Figure 2: Optical assembly of the EF-S 18-55mm f/3.5-5.6 IS | ||||||
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| Figure 3: MTF characteristics of the EF-S 18-55mm f/3.5-5.6 IS | ||||||
| Bold lines: 10 lp/mm, fine lines: 30 lp/mm. Black lines are the MTF at full aperture; the blue lines at f/8. Solid lines represent sagittal (radial) MTF and the broken lines represent meridional (tangential) MTF. | ||||||
Feature 3 : New smaller high-performance image stabilizer unit A priority of this lens design was to keep its weight and size on par with that of the non-IS EF-S 18-55mm f/3.5-5.6 II USM. This meant that the image stabilizer unit had to fit in a very tight space. We slashed the size and weight of the image stabilizer unit by redesigning the unit and reducing its component count. Some characteristics of the unit's new construction (Photo 2, Figure 4) are:
An optimized algorithm controls the drive of the new image stabilizer unit. With image stabilization on, the lens can deliver a stabilization gain of four f-stops in shutter speed.* The lens is also able to automatically distinguish between panning and camera shake in normal shooting, and adjusts the IS mode accordingly. This feature permits for optimal image-stabilization in both situations and frees the user from concerns about mode selection. * Generally, the effective limit for stable unaided handheld shooting is a shutter speed of about 1/[focal length x 1.6] seconds for APS-C sensor cameras. | ||||||
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| Photo 2: Image stabilizer unit of the EF-S 18-55mm f/3.5-5.6 IS | ||||||
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| Figure 4: Exploded view of the image stabilizer unit | ||||||
Feature 4 : Optimal optics for digital SLRs The lens configuration and coatings have been designed to minimize the flare and ghosting due to surface reflections from the imaging sensor that is found in digital SLRs. The configuration and coatings also provide excellent color balance. Other features • Fast autofocusing A high-speed CPU and an optimized AF algorithm control the compact drive motor for fast autofocusing. • Minimum focusing distance of 0.25m The minimum focusing distance is 0.25m at all focal lengths, which is closer than that on the EF-S 18-55mm f/3.5-5.6 II USM. The maximum magnification is 0.34 (at 55mm). • Circular aperture produces beautiful bokeh The lens features an electro-magnetic diaphragm with a circular aperture that produces attractive bokeh (blurring effects). • Redesigned switch shape prevents accidental mode changes The focus mode switch has been reshaped to prevent the switch from being moved accidentally while shooting or transporting. • Improved operability and high-grade exterior finish This lens has been furnished with the same zoom-ring pattern and coating as our high-end models, giving a firmer grip and creating a high-grade exterior finish. • Environmentally friendly design The lens optics uses only environmentally friendly lead-free glass. Furthermore, the lens design meets the environmental requirements of the European Union's RoHS Directive (Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment). |
