Standard f/4L-series zoom lens with image stabilizer
The EF24-105mm f/4L IS USM (Photo 1) is a new high-performance standard zoom lens developed to complete the f/4L zoom lens line-up with the EF17-40mm f/4L USM and EF70-200mm f/4L USM.
The development concept is as follows:
Wide zoom range covering the range from 24mm wide-angle to 105mm medium telephoto
Ultrahigh image definition
Image stabilization equal to about three shutter speeds
Digital cameras compatibility
Dust- and moisture-proof construction
Optical system features
Wide zoom range
The optical system of the EF24-105mm f/4L IS USM is a new design featuring image stabilization in addition to high ratio zoom and ultrahigh image definition. Use of a multi-group zoom mechanism where all lens groups move during zooming allows about a nearly 4.4x zoom ratio from 24mm wide-angle to 105mm medium telephoto.
It also adopts the inner focusing system by the second group and the parallel shift-lens image stabilizer system by the twelfth and thirteenth groups (image stabilizer lens group)(see Fig. 1).
Fig. 1 EF24-105mm f/4L IS USM Optical System |
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Ultrahigh image quality - the trademark of the L-series
The optical system of 18 elements in 13 groups uses three precision aspherical lenses of two types, molded glass (GMo) and replica. The system helps minimize distortion that occurs at wide-angle focal lengths and aberrations that occur during zooming, enabling neutral and natural rendering of the subject throughout the entire zoom range.
In addition, the Super UD lens, made of ultralow-dispersion glass developed by Canon, is employed for minimum chromatic aberrations throughout the entire zoom range. The lens delivers excellent quality images with both high resolution and contrast throughout the entire zoom and focusing ranges, which can be expected only with the L-series lenses (see Fig. 2).
Fig. 2 MTF Characteristic Charts of EF24-105mm f/4L IS USM
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Closest focusing distance of 0.45 meters
The minimum focusing distance of 0.45 meters through the entire zoom range is achieved by increasing the power of the focusing lens group. Maximum magnification is 0.23x at 105mm telephoto (field of view: 106 x 158mm).
Lens coating optimized for use with digital SLR cameras
The EF24-105mm f/4L IS USM has element shape and coating optimized for use with digital SLR cameras. As a result, it successfully realizes both good color balance and minimization of ghost and flare attributable to surface reflections from the digital imaging element.
Functional features
Image stabilization of about three shutter speeds
The EF24-105mm f/4L IS USM is the first L-series standard zoom lens with an image stabilizer.
With a dedicated high-performance compact IS unit and a vibration gyro for precise camera shake detection, the EF24-105mm f/4L IS USM achieves image stabilization equivalent to using a shutter speed about three steps faster. It has the following excellent features as well:
| • | The image stabilizer is activated within half a second after pressing the shutter button halfway, allowing the user to capture the decisive moment. |
| • | The same image stabilizer effects can be attained when using a monopod as in hand-held shooting. |
| • | There are no restrictions on using a tripod. |
Excellent dust- and moisture-proof construction
By employing dust- and moisture-proof construction (see Fig. 3) in the lens mount, switch panel, zoom ring, focusing ring and zoom elements in the lens to prevent dust and water from reaching the interior, the lens can be used in harsh environments.
*It applies when the lens is used with a dust- and moisture-proof body.
Circular aperture for attractive bokeh effects
Thanks to the EMD (electromagnetic diaphragm), the circular aperture of the lens provides attractive blur effects (bokeh).
Silent, high-speed AF
In addition to the silent ring-type ultrasonic motor (USM) and inner focusing system, high-speed CPU and optimized AF algorithm contribute to high-speed autofocus.
Manual focusing enabled even in AF mode
The EF24-105mm f/4L IS USM has full-time mechanical manual focusing that allows manual focus after one-shot AF operation without leaving AF mode.
Switch design that prevents unintended switching
The focus mode switch and IS switch are designed to prevent unintended switching during shooting or when being carried.
Non-rotating filter ring
Since the filter does not rotate while zooming or focusing, it allows smooth operation of circular PL (polarizing) filters.
To prevent vignetting, using the Canon 77mm PL-CII filter is recommended.
Dedicated large scalloped hood with superb light blocking
The EW-83H, a large scalloped hood dedicated to the EF24-105mm f/4L IS USM, has superior antireflection flocking on the inner surface. It is highly effective in keeping unwanted light out of the lens.
Environmentally friendly design
The optical system contains only environmentally friendly lead-free glasses.
Effective from July 2006, EU (European Union) will restrict the use of certain hazardous substances* in the electrical and electronic equipment according to the ''EU's Restrictions on Hazardous Substances (RoHS) Directive''.
The EF24-105mm f/4L IS USM is already in compliance with Canon's own standard covering the RoHS directives including those still being finalized.
*Six substances: lead, mercury, cadmium, hexavalent chromium, bromine flame retardant PBB (polybrominated biphenyl), and PBDE (polybrominated diphenyl ether).
Fully redesigned telephoto zoom lens with image stabilizer
The EF70-300mm f/4-5.6 IS USM (Photo 2) is the telephoto zoom lens developed as the successor to the EF75-300mm f/4-5.6 IS USM, the world's first interchangeable lens with image stabilizer for SLR cameras.
As digital SLR cameras became rapidly popular, the EF70-300mm f/4-5.6 IS USM is fully redesigned with improved optical system and image stabilizer.
The development concept is as follows:
Higher image quality than its predecessor
Image stabilization of about three shutter speeds
Compatible with digital cameras
Higher-speed AF
Better usability
Optical system features
Higher image quality than its predecessor
With improved power of each lens group, EF70-300mm f/4-5.6 IS USM has a wider zoom range than its predecessor (70mm vs. 75mm) wide-angle focal length while maintaining the 15 elements / 10 group optical system and six-group zoom. The use of a UD lens in the seventh element minimizes residual chromatic aberrations, achieving excellent quality images with higher resolution and contrast throughout the entire zoom range than its predecessor (see Fig. 4).
Fig. 4 MTF Characteristic Charts of EF70-300mm f/4-5.6 IS USM |
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It also adopts the front focusing system by the first group and the parallel shift-lens image stabilizer system by the second group (image stabilizer lens group (Fig. 5).
Fig. 5 EF70-300mm f/4-5.6 IS USM Optical System |
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Lens coating optimized for use with digital SLR cameras
The EF70-300mm f/4-5.6 IS USM has element shape and coating optimized for use with digital SLR cameras. As a result, it successfully realizes both good color balance and minimization of ghost and flare attributable to surface reflections from the digital imaging element.
Functional features
Image stabilization of about three shutter speeds
With a newly-developed dedicated IS unit and an improved control algorithm, the EF70-300mm f/4-5.6 IS USM achieves image stabilization equivalent to using a shutter speed about three steps faster. It has the following excellent features as well:
| • | The image stabilizer is activated within half a second after pressing the shutter button halfway, allowing the user to capture the decisive moment. |
| • | Either of the image stabilizer modes can be selected: Mode 1 is effective for stationary subjects and mode 2 is best for panning with a moving subject. |
| • | The same image stabilizer effects can be attained when using a monopod as in hand-held shooting. |
| • | There are no restrictions on using a tripod. |
Much higher-speed AF
The high-speed CPU and optimized AF algorithm contribute to much faster autofocusing than its predecessor while maintaining the same front focusing system and micro USM drive.
Zoom ring locking mechanism
When carrying a camera on a neckstrap with this lens attached, the weight of the lens system could cause the lens to extend, possibly damaging the lens if it hits something, Therefore, it has a locking zoom ring that keeps the lens at the wide angle (shortest overall length) when it is being carried.
Sliding the zoom ring lock lever on the side of the lens locks the zoom ring position.
Switch design that prevents unintended switching
The focus mode switch and IS switch are designed to prevent unintended switching during shooting or when being carried.
Circular aperture for attractive bokeh
Thanks to the EMD (electromagnetic diaphragm), the circular aperture of the lens provides attractive bokeh (blur effects).
Environmentally friendly design
The optical system contains only environmentally friendly lead-free glasses. The EF70-300mm f/4-5.6 IS USM is also in compliance with Canon's own standard to cover the RoHS directive articles.
This issue of the Technical Report introduces two high-performance zoom lenses.
Tables 1 and 2 show the major specifications and depth-of - field data of both lenses.