Concept of development
With the increasing popularity of digital SLR cameras, calls for large aperture single-focal length lenses with excellent image quality and pleasing bokeh (blur effects) for portraits have increased. To meet this demand, the EF85mm f/1.2L II USM was released in March 2006, and now the EF50mm f/1.2L USM (Photo 1), developed to further improve the L-series lineup of ultralarge aperture single-focal length lenses, is available.
The key development concepts are as follows:
• Ultralarge maximum aperture of f/1.2
• Superb image quality over the entire shooting area
• Dust - and moisture - resistant construction
• Digital camera compatibility
Feature 1: Ultralarge f/1.2 maximum aperture
The optical system of the EF50mm f/1.2L USM is completely new. It uses a Gauss type optical system with 8 elements in 6 groups and unit focusing (Fig. 1).
The ultralarge aperture of f/1.2 and high definition throughout the entire shooting area befitting an L-series lens.
Feature 2: Superb image quality over the entire shooting area
The 8th element is a large aperture precision aspherical lens, which helps minimize aberrations that occur during focusing giving a large f/1.2 maximum aperture with high definition befitting of an L-series lens throughout the entire shooting area (Fig. 2).
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* Thick lines: 10 lines/mm; thin lines: 30 lines/mm. The darker black lines represent the MTF characteristics at maximum aperture; the blue lines at f/8. The solid lines trace the radical S (sagittal) curve, while the broken lines trace the tangential M (meridional) curve. |
Feature 3: Excellent dust- and moisture-resistant construction
By utilizing dust- and moisture-resistant construction (Fig. 3) in the lens mount, switch panel and focusing ring to prevent dust and water from reaching the interior, the lens can be used in harsh environments.
*This applies when the lens is used with a dust- and moisture-resistant EOS body and a filter is attached to the front of the lens.
Feature 4: Lens coating optimized for use with digital SLR cameras
The EF50mm f/1.2L USM has element curvature and coating optimized for use with digital SLR cameras. It successfully realizes both good color balance and minimization of ghost and flare attributable to surface reflections from the digital imaging element.
Feature 5: Superb operability
• Circular aperture for attractive bokeh effects
Thanks to the electromagnetic diaphragm's (EMD) circular aperture, the lens provides attractive bokeh (blur effects).
• Silent , High-speed AF
The ring-type ultrasonic motor (USM), high-speed CPU and optimized AF algorithm contribute to silent, speedy autofocus.
• Manual focusing - even in AF mode
The EF50mm f/1.2L 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 is designed to prevent unintended switching during shooting or while being carried.
• Non-rotating filter ring
Since the EF50mm f/1.2L USM does not change in length and the filter does not rotate or move while focusing, it allows smooth operation of accessories including circular polarizing (PL) filters.
• Dedicated large cylindrical hood with superb light blocking
The ES-78, a large cylindrical hood dedicated to the EF50mm f/1.2L USM, has superior antireflection flocking on the inner surface. It is very effective in keeping unwanted light out of the lens (Photo 2).
• Distance information for improving flash exposure precision
Distance information is sent to the camera during AF, making the EF50mm f/1.2L USM compatible with the E-TTL II autoflash system for optimal flash exposure.
Feature 6: Environmentally friendly design
The optical system contains only environmentally friendly lead-free glasses. Furthermore, EU (European Union) restricts the use of certain hazardous substances in the electrical and electronic equipment according to the ''EU's Restrictions on Hazardous Substances (RoHS) Directive''. The EF50mm f/1.2L USM meets Canon's own standard to comply with the RoHS Directive.
*The 6 substances: lead, mercury, cadmium, hexavalent chromium, bromine flame retardant PBB (polybrominated biphenyl) and PBDE (polybrominated diphenyl ether).
Lightweight compact L-series telephoto zoom lens with image stabilizer
Concept of development
The EF70-200mm f/4L IS USM (Photo 3) was developed to meet the needs of many users who wanted an image stabilizer in the EF70-200mm f/4L USM, a lightweight, high-performance zoom lens with excellent mobility.
The development concepts are as follows:
• Pursuit of high quality throughout the entire zoom range
• Image stabilization equal to about four shutter speeds
• Digital camera compatibility
• Dust- and moisture-resistant construction
Feature 1: Compact optical system
The optical system of this lens is a new design featuring high definition on par with the EF70-200mm f/4L USM and image stabilization.
The basic lens configuration is the same as the EF70-200mm f/4L USM, but the latest design technology has been used to add the image stabilizer while maintaining the same compact size as the EF70-200mm f/4L USM (Fig. 4).
Feature 2: High definition throughout the entire zoom range
The optical system of 20 elements in 15 groups uses one fluorite lens element and two UD lens elements, which helps minimize the chromatic aberrations that tend to occur in telephoto lenses. It delivers high image quality (Fig. 5) with both high resolution and contrast befitting of an L-series lens throughout the zoom range and shooting area.
Feature 3: Image stabilization equal to about four shutter speeds
The EF70-200mm f/4L USM image stabilizer lens group (6th group) utilizes shift-lens image stabilization. In addition to a dedicated high-performance IS unit and a vibration gyro for precise camera shake detection, an improved image stabilization algorithm gives image stabilization equivalent to using a shutter speed about four steps faster (Fig. 6, Photos 4 and 5).
The image stabilizer used in the EF70-200mm f/4L USM also has the following excellent features.
Sample Shot 1
(EOS-1Ds Mark II at 70mm, 1/5sec,
image stabilizer on)
Sample Shot 2
(EOS-1Ds Mark II at 70mm, 1/5sec,
image stabilizer off)
| · | The image stabilizer has two modes: Mode 1 is effective for stationary subjects and Mode 2 is best for panning with a moving subject. |
| · | The same stabilizer effects as hand-held shooting can be attained when using a monopod. |
| · | There are no restrictions on using a tripod. |
| · | The image stabilizer can also be used when using the EF1.4X II/ EF2X II extenders.* |
| * | There are restrictions for some cameras. Please refer to Table 3. |
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| * | The autofocus is supported for the EOS-1Ds Mark II, EOS-1Ds, EOS-1D Mark II N, EOS-1D Mark II, EOS-1D, EOS-1v HS and EOS-3 at the center AF points. |
| ** | The Image Stabilization function can be used on the following camera models: EOS-1Ds Mark II, EOS-1Ds, EOS-1D Mark II N, EOS-1D Mark II, EOS-1D, EOS 5D/30D/20D/20Da/ 10D/Kiss Digital X/Kiss Digital N/Kiss Digital/D60/D30, EOS-1v HS, EOS-1N HS/DP/RS, EOS-3, EOS 7/7s/55/Kiss/New Kiss/Kiss III/Kiss III L/Kiss 5/Kiss 7/Kiss Lite/3000/888/IX E/ IX 50, EOS DCS1/DCS3/D2000/D6000/D30. |
Feature 4: Lens coating optimized for use with digital SLR cameras
The EF70-200mm f/4L IS USM has element lens curvature and coating optimized for use with digital SLR cameras. As a result, it successfully gives both good color balance and minimization of ghost and flare attributable to surface reflections from the digital imaging element.
Feature 5: Excellent dust- and moisture-resistant construction
By utilizing dust- and moisture-resistant construction (Fig. 7) in the lens mount, switch panel, zoom ring and focusing ring to prevent dust and water from reaching the interior, the lens can be used in harsh environments.*
*This applies when the lens is used with a dust- and moisture-resistant EOS body.
Feature 6: Superb operability
• High-speed silent autofocus
The use of ring USM, inner focus, a high-speed CPU and an optimized autofocus algorithm ensures autofocusing that is both quick and quiet.
• Manual focusing enabled even in AF mode
The EF70-200mm f/4L IS USM has full-time mechanical manual focusing that allows manual focus after one-shot AF operation without leaving AF mode.
• Extender support
The EF1.4X II and EF2X II extenders can be used with this lens.
• Tripod Ring A II (W)
The newly developed Tripod Ring A II (W) is available as an accessory. Improvements to the shape of the locking screw ensure the lens is fastened more securely than with its predecessor (Photo 6).
• Cylindrical hood with superb light blocking
Like the EF70-200mm f/4L USM, the EF70-200mm f/4L IS USM uses the ET-74 cylindrical hood that has excellent antireflection flocking on the inner surface.
• Distance information for improving flash exposure precision
Distance information is sent to the camera during AF, thus making the EF70-200mm f/4L IS USM compatible with the E-TTL II autoflash system for the optimal flash exposure.
• Switch design that prevents unintended switching
The switches including the focus mode switch are designed to prevent unintended switching during shooting or while being carried.
Feature 7: Environmentally friendly design
The optical system contains only environmentally friendly lead-free glasses. The EF70-200mm f/4L IS USM meets as well Canon's own standard to comply with the RoHS Directive.
This issue of the Technical Report introduces two new L-series lenses.
Table 1, 2 and 3 show the major specifications and data on use with extension tubes and extenders.