This month's Technical Report presents the latest technical information on EF70-200mm f/2.8L IS USM, a new EF lens with image stabilizer, available in late September. Also provided is information on the new extenders EF1.4X II and EF2X II, marketed this spring, but not yet reported on here.
Concept of development
The EF70-200mm f/2.8L IS USM lens (see Photo 1) was developed in response to the professional photojournalist community which has sought the addition of an image stabilizer feature to the 70-200mm class L-series lens. The concept behind its development is as follows: |
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Feature 1: Ultra-high image quality
Ultra-high image quality
The newly designed optical system of the EF70-200mm f/2.8L IS USM is based on the reputable EF70-200mm f/2.8L USM and retains the same outstanding level of image quality. This fixed-length lens has a zoom system of five lens groups with three moving groups. Inner focusing is accomplished by the second group, and an image stabilizer function is included. In the optical system comprised of 23 elements in 18 groups (see Fig. 1), UD (Ultra-Low Dispersion) lens is used in elements 2, 3, 11, and 16, to correct residual chromatic aberrations, resulting in extremely sharp images with excellent contrast throughout the entire zoom and focusing range (see 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 lighter lines represents the characteristics at f/8. The solid lines trace the radial S (sagittal) curve, while the broken lines trace the tangential M (meridional) curve.
Minimum focusing distance of 1.4 meters
A minimum focusing distance of 1.4m over the full zooming range was achieved by increasing the power of the focusing group. It also gives a maximum magnification of 0.17x at 200mm telephoto (140mm x 211mm image field).
Circular aperture for attractive defocusing effects
A newly developed circular aperture which remains virtually circular from f/2.8 to f/5.6 (see Fig. 3) provides attractive out-of-focus effects that only a large aperture lens can achieve.
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Optical configuration considering digital SLRs
Surface reflections of digital SLR imaging sensors are much greater than those of film. The optical system of the EF70-200mm f/2.8L IS USM is designed to minimize the negative effects to the images.
Environmentally friendly lead-free glass
Giving careful consideration to the environment, the optical system of the EF70-200mm f/2.8L IS USM consists of lead-free glass only.
Feature 2: High-performance image stabilizer
The EF70-200mm f/2.8L IS USM utilizes the same shift-type image stabilizer system as conventional Canon IS (image stabilizer) lenses, in which the supplementary optical system instantly moves perpendicular to the optical axis to cancel out the camera shake. It offers two image stabilizer modes: mode 1 effective for shooting stationary subjects and mode 2 effective for panning with a moving subject.
3-stop image stabilizing effect (shutter speed conversion)
Previous Canon IS lenses provided improvement in image stabilization equivalent to using a shutter speed two stops faster. The new image stabilizer unit featured in the EF70-200mm f/2.8L IS USM improves the sensitivity of the supplementary optical system and optimizes drive controls to achieve approximately 3-stop image stabilizer improvement (see Fig. 4). This improvement prevents image shake with a probability of better than 90 percent even when shooting at 200mm telephoto and a shutter speed of 1/25 second.
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Startup time of 0.5 seconds
The EF70-200mm f/2.8L IS USM adopted a new type of compact, lightweight, high-performance vibration gyro and improved signal processing circuits to start image stabilizer operation within about 0.5 seconds after pressing the shutter button halfway (previous models took about one second), allowing the user to capture the decisive moments without blurring the image.
Automatic tripod detection and malfunction prevention
The EF70-200mm f/2.8L IS USM incorporates the same automatic tripod detection function that is used with Canon’s super-telephoto IS lenses. Output signals from the vibration gyro are analyzed to determine if the lens is hand-held or mounted on a tripod. When the image stabilizer function is turned on and the lens detects that a tripod is in use, the shift lens is electronically centered and locked on the optical axis, preventing improper operation.
Image stabilizer effects on monopod equal to in hand-held shooting
Many professional sports photographers regularly use a monopod. The same image stabilizer effects can be attained when using a monopod as in hand-held shooting.
Feature 3: Silent, high-speed AF
The AF performance of the EF70-200mm f/2.8L IS USM is up to about twice as fast as that of the EF70-200mm f/2.8L USM by improving the AF drive circuits and AF algorithm of the ring USM drive and inner focus design.
Feature 4: Excellent dust and moisture resistance
Dust and moisture resistant construction is introduced in the mount area, switch panel, zoom ring and focusing ring to prevent water and dust from reaching the interior of the lens, enabling its use in harsh shooting conditions.
Feature 5: Outstanding operational ease
Focusing range selection switch
Focusing range can be set to two ranges with the focusing range selection switch: 1.4m to infinity or 2.5m to infinity. In shooting of distant subjects, it is useful to select 2.5m to infinity in order to eliminate unnecessary AF search for near subjects which are out of focusing range. This reduces AF focusing time.
Manual focusing available in AF mode
The EF70-200mm f/2.8L IS USM incorporates full-time mechanical manual focusing that allows manual focusing after one-shot AF operation without leaving AF mode.
Easy-to-operate, wide rubber zoom ring
A wide rotating zoom ring is used to enable fine-tuning of framing of the image.
Non-rotating filter ring
Since the filter ring does not rotate and the overall lens length does not change when zooming or focusing, it facilitates use of circular PL (polarizing) filters and gelatin filter holders without additional adjustment after focusing.
Note: Both gelatin filter holders IIIand IV can be used. One hood can be used on the type IV gelatin filter holder, but not on the Type III as vignetting may occur.
Detachable ring-type tripod mount
The EF70-200mm f/2.8L IS USM comes with a detachable ring-type tripod mount for the stable use with a tripod.
Feature 6: Compatible with extenders
When used together with Extenders EF1.4X or EF1.4X II, the EF70-200mm f/2.8L IS USM becomes a 98-280mm f/4 super-telephoto IS zoom lens. Likewise, used together with the EF2X or the EF2X II, it is a 140-400mm f/5.6 super-telephoto IS zoom lens.
The filter size of the EF70-200mm f/2.8L IS USM is 77mm, and the hood is the ET-86 (Petal-type). The lens dimensions are 86.2mm dia. x 197mm, and its weight is 1,470g (body only, 120g more with a tripod mount). The price is ¥280,000, including the hood, lens case, and ring-type tripod mount B (W) before tax in Japan.
Features of the new extenders, EF1.4X II and EF2X II
While maintaining the excellent imaging performance of the master lens, the high-performance extenders, EF1.4X II and EF2X II (see Photos 2 and 3), extend the focal length by 1.4 times (EF1.4X II) and 2 times (EF2X II) They have the following features.
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(1)Advanced dust and moisture resistance
The new extenders have a rubber ring on the camera-side mount, dust and moisture resistance equal to that with the EOS-1V around the outer edge of the lens-side mount, and gaskets at the extender release knob. These treatments give the extenders outstanding dust and moisture resistance.
(2)High image quality
EF1.4X II
With five elements in four groups, the optical system of the EF1.4X II (see Fig. 5) is exactly the same as that of the previous EF1.4X; however, the improved features such as new anti-reflection construction inside the barrel and edge-blackening of the lens elements reduce flare, providing even clearer image quality than the EF1.4X.
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| Fig. 5 EF1.4X II Optical Schematic | Fig. 6 EF2X II Optical Schematic |
EF2X II
With seven elements in five groups, the optical system of the EF2X II (see Fig. 6) was redesigned and optimized for the compatible master lenses, achieving more advanced imaging performance than the EF2X (see Fig 7).
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(3)Compatible with a wide range of EF lenses
As with the earlier extenders, the new models work with eighteen existing single focal length L-series lenses of 135mm or longer, in addition to the EF70-200mm f/2.8L USM, the EF70-200mm f/2.8L IS USM, the EF70-200mm f/4L USM, and the EF100-400mm f/4.5-5.6L IS USM. The effective maximum aperture of the master lens will be lowered by one stop when used with the EF1.4X II, and by two stops with the EF2X II.
The EF1.4X II is 72.8mm dia. x 27.2mm with a weight of 220g. The EF2X II is 71.8mm dia. x 57.9mm with a weight of 265g. The price for either model is ¥56,000 in Japan (pouch included, without tax).
*This issue of the Technical Report mainly introduces the EF70-200mm f/2.8L IS USM, a new image stabilizer zoom lens. Tables 1 to 6 depict the depth-of-field data under each condition.
•Table 1 : Depth of Field Data for EF70-200mm f/2.8L IS USM at Wide-angle
(f=70mm)
•Table 2 : Depth of Field Data for EF70-200mm f/2.8L IS USM at Wide-angle
(f=70mm) with EF1.4X II
•Table 3 : Depth of Field Data for EF70-200mm f/2.8L IS USM at Wide-angle
(f=70mm) with EF2X II
•Table 4 : Depth of Field Data for EF70-200mm f/2.8L IS USM at Telephoto
(f=200mm)
•Table 5 : Depth of Field Data for EF70-200mm f/2.8L IS USM at Telephoto
(f=200mm) with EF1.4X II
•Table 6 : Depth of Field Data for EF70-200mm f/2.8L IS USM at Telephoto
(f=200mm) with EF2X II