January 2010
A new product of the EOS DIGITAL series, a high power standard lens with superior performance.
Photo 1: EF-S 18–135mm f/3.5–5.6 IS
Photo 2: EF-S 15–85mm f/3.5–5.6 IS USM
In this month’s technical report we present two new lenses announced in October 2009 — the EF-S 18–135mm f/3.5–5.6 IS and the EF-S 15–85mm f/3.5–5.6 IS USM.
EF-S 18-135mm f/3.5-5.6 IS
Development objectives for the EF-S 18–135mm f/3.5–5.6 IS
In answer to the strong market demand for a standard zoom lens with excellent mobility, we developed the EF-S 18–135mm f/3.5–5.6 IS (Photo 1) as a zoom lens specifically for the EOS 7D and other APS-C sensor EOS Digital series ※1 cameras. The lens’ primary features are described below.
※1. EF-S lens compatible cameras (as of December 2009): EOS 7D, EOS 50D, EOS 40D, EOS 30D, EOS 20D, EOS 20Da, EOS Kiss X3, EOS Kiss X2, EOS Kiss F, EOS Kiss Digital X, EOS Kiss Digital N, EOS Kiss Digital
Figure 1: Optical assembly of the EF-S 18–135mm f/3.5–5.6 IS
Figure 2: MTF characteristics of the EF-S 18–135mm f/3.5–5.6 IS
- How to read MTF charts
- Bold lines: 10 lp/mm, fine lines: 30 lp/mm. Black lines are the MTF characteristics at full aperture; the blue lines at f/8. Solid lines represent sagittal (radial) MTF and the broken lines represent meridional (tangential) MTF.
Feature 1 — Outstanding optical performance
This zoom lens uses the zoom architecture (in which all five lens groups move when zooming) from the EF-S 18–200mm f/3.5–5.6 IS, which went on sale in 2008, but reduces the lens weight to 455grams and the filter diameter to 67 millimeters with a zoom ratio of 7.5x (focal length range of 18 to 135mm) by optimally distributing the magnification powers among the lens groups. The inclusion of a UD lens element in the final group corrects chromatic aberration, and the precision aspherical lens element in the final group provides excellent aberration correction, particularly of spherical aberration, and ensures top image quality at all zoom settings (figures 1 and 2). For reference, the lens’s focal length range is equivalent to 29 – 216mm in 35mm-film format.
Feature 2 — Fast and comfortable autofocus
The lens features exceptionally fast and comfortable autofocusing. The inner-focusing system, which focuses using the second lens group, is powered by a DC motor and controlled by a high-speed CPU and optimized AF algorithm. The focus mode switch has been reshaped to prevent it from being accidentally moved while shooting or transporting the lens.
Feature 3 — Excellent image stabilization
The image stabilization system on this lens shifts part of the fourth lens group (lens elements 11 and 12) perpendicularly to the optical axis to counter camera shake. The system is driven by a dedicated IS unit of the same type used on the EF-S 18–55mm f/3.5–5.6 IS lens. The IS unit’s control algorithm has been tuned to suit the lens’s architecture and characteristics, delivering a stabilization gain of about four f-stops in shutter speed. ※2
The lens is also able to distinguish, using the output of the vibration gyroscope, between pan shooting and normal shooting, and automatically adjusts the IS mode accordingly (Photo 3). This feature frees the user from concerns about mode selection.
Photo 3: EF-S 18–135mm f/3.5–5.6 IS switch panel
A mechanism that prevents accidental operation when using a tripod makes it possible to shoot using a tripod and image stabilization. The lens’s image stabilization function is effective even for slight camera shake during tripod shooting. ※3, ※4, ※5
- ※2. Image stabilization generally reaches its effective limit at a shutter speed of about 1/[focal length x 1.6] seconds.
- ※3. Image stabilization is most effective at shutter speeds between 1/200 and 1/30 of a second.
- ※4. Image stabilization has no discernable benefit at shutter speeds slower than 1/30 of a second.
- ※5. In certain conditions, depending on the tripod type or camera, there may be less blurring in the resulting photograph when the image stabilization function is off.
Other features
This zoom features an electro-magnetic diaphragm with a circular aperture that produces natural bokeh (blur effects) with uniform roundness, and its optimized coating technology minimizes flare and ghost for high-grade photos.
A number of new exterior design elements have been added to give the lens a more distinguished look than previous EF-S lenses. These include a new leather-tone coating for an elegant finish, an electrocast “Canon” badge located on the lens barrel, a platinum ring at the front of the zoom ring, and white-silver embossed figures for the model name and EF-S logo.
Accessories
The petal-shaped EW-73B hood (Photo 4) attaches with a two-pronged bayonet mount. The hood’s inner wall has been given a flocking treatment for better anti-reflective performance. The lens fits into the LP1116 soft pouch case.
All these features have gone into the EF-S 18–135mm f/3.5–5.6 IS to deliver both high performance and excellent value for money.
Photo 4: Petal-shaped EW-73B hood for the EF-S 18–135mm f/3.5–5.6 IS
EF-S 15-85mm f/3.5-5.6 IS USM
Development objectives for the EF-S 15–85mm f/3.5–5.6 IS USM
The EF-S 15–85mm f/3.5–5.6 IS USM (Photo 2), a standard zoom lens specifically designed for EF-S lens compatible cameras, ※1 marks a huge advancement over the EF-S 17–85mm f/4–5.6 IS USM, which went on sale in 2004. This zoom lens was developed to satisfy the demands of advanced amateurs in terms of image quality, specs, operability, and style.
※1. EF-S lens compatible cameras (as of December 2009): EOS 7D, EOS 50D, EOS 40D, EOS 30D, EOS 20D, EOS 20Da, EOS Kiss X3, EOS Kiss X2, EOS Kiss F, EOS Kiss Digital X, EOS Kiss Digital N, EOS Kiss Digital
Figure 3: Optical assembly of the EF-S 15–85mm f/3.5–5.6 IS USM
Figure 4: MTF characteristics of the EF-S 15–85mm f/3.5–5.6 IS USM
Feature 1 — Superb image quality even at 24mm
The zoom on this lens moves all four lens groups to adjust the zoom. The optimized distribution of magnification powers among the lens groups lets the lens cover a broad focal length range from 15 to 85mm (a 5.7x zoom ratio).
The inclusion of a UD lens element in the third lens group corrects chromatic and spherical aberrations, and the aspherical lens elements in the second, third, and fourth lens groups correct the high-order coma flare and distortion that wide-angle lenses are prone to. This optical design ensures the lens renders sharp images across the entire frame at all focal lengths (the focal length range is equivalent to 24 – 136mm in 35mm-film format) (figures 3 and 4).
Feature 2 — Superior operability
This lens is equipped with an inner-focusing system using the second lens group, similar to the EF-S 18–135mm f/3.5–5.6 IS. The minimum focusing distance at all zoom settings is just 35 centimeters.
The lens movement is exquisitely smooth thanks to the metal lens barrel construction. The ring USM drive, high-speed CPU, and optimized AF algorithm provide the lens with fast autofocusing as well as full-time manual control. The lens is exceedingly well balanced with a superb feel and grip.
The lens also features the reshaped focus mode switch found on our most recent lenses to avoid unintended mode changes, a special mount design that prevents the lens from being mounted by mistake on cameras that do not support EF-S lenses, and a rubber ring that stops the lens from scratching the camera.
Feature 3 — Excellent image stabilization
The image stabilization system shifts part of the third lens group (lens elements 12 and 13) perpendicularly to the optical axis to offset camera shake. The system is driven by the same IS unit found on the EF-S 18–135mm f/3.5–5.6 IS. The IS unit’s control algorithm has been tuned to suit the lens’s architecture and characteristics, delivering a stabilization gain of about four f-stops in shutter speed.※2 This allows more frequent use of slow shutter speeds.
A mechanism on the lens prevents accidental operation when using a tripod. It is possible to shoot while using a tripod with image stabilization on. (We recommend turning image stabilization off to save battery power when using a tripod.)
As with our past IS lens series, image stabilization can be used when shooting with a monopod.
The image stabilization gain when using a monopod is the same as when shooting handheld.
- ※2. Image stabilization generally reaches its effective limit at a shutter speed of about 1/[focal length x 1.6] seconds.
Other features
This zoom features an electro-magnetic diaphragm with a circular aperture that produces natural bokeh (blur effects) with uniform roundness, and its optimized coating technology minimizes flare and ghost for high-grade photos. 。
A number of new exterior design elements have been added to give the lens a more distinguished look than previous EF-S lenses. These include a leather-tone coating for an elegant finish, an electrocast “Canon” badge located on the lens barrel, a platinum ring at the front of the zoom ring, and white-silver embossed figures for the model name and EF-S logo.
And naturally both this lens and the EF-S 18–135mm f/3.5–5.6 IS use only environmentally friendly lead-free optical glass.
Accessories
The petal-shaped EW-78E hood (Photo 5) attaches with a two-pronged bayonet mount.
The hood’s inner wall has been given a flocking treatment for advanced anti-reflective performance. The hood’s exterior features a new leather-tone coating to match the high-end finish of the lens.
The lens fits into the LP1116 soft pouch case (Photo 6), which is also used for the EF-S 18–135 mm f/3.5–5.6 IS.
This month we have featured two new Canon zoom lenses that are perfectly matched for the EOS 7D. We are certain that once you feel these lenses in your hand and try them out, you will be excited by just how much more enjoyable these highly mobile lenses will make your photography life.
Photo 5: Petal-shaped EW-78E hood for the EF-S 15–85mm f/3.5–5.6 IS USM
Photo 6: LP1116 soft pouch lens case
| Model | EF-S 18-135mm F3.5-5.6 IS |
|---|---|
| Compatible image size | APS-C |
| Equivalent 35mm-film format | 29 – 216mm |
| Lens construction | 16 elements in 12 groups |
| UD lens elements | 1 |
| Aspherical lens elements | 1 |
| Circular aperture | Yes |
| Min. focusing distance | 0.45m (at 135mm) |
| Max. magnification | 0.21x (at 135mm) |
| Image stabilization gain | ~4 f-stops |
| Filter diameter | 67mm |
| Max. diameter | 75.4mm |
| Overall length | 101mm |
| Weight | 455grams |
| Hood | EW-73B (sold separately) |
| Case | LP1116 (sold separately) |
| Suggested retail price | ¥65,000 (sold separately) |
Table 1: Specifications of the EF-S 18–135mm f/3.5–5.6 IS
| Model | EF-S 15-85mm F3.5-5.6 IS USM |
EF-S17-85mm F4-5.6 IS USM |
|---|---|---|
| Compatible image size | APS-C | APS-C |
| Equivalent 35mm-film format | 24-136mm | 27-136mm |
| Lens construction | 17 elements in 12 groups | 17 elements in 12 groups |
| UD lens elements | 1 | - |
| Aspherical lens elements | 3 | 1 (double-sided aspherical lens) |
| Circular aperture | Yes | Yes |
| Min. focusing distance | 0.35m | 0.35m |
| Max. magnification | 0.21x | 0.20x |
| Image stabilization gain | ~4 f-stops | ~3 f-stops |
| Filter diameter | 72mm | 67mm |
| Max. diameter | 81.6mm | 78.5mm |
| Overall length | 87.5mm | 92mm |
| Weight | 575grams | 475grams |
| Hood | EW-78E (sold separately) | EW-73B (sold separately) |
| Case | LP1116 (sold separately) | LP1116 (sold separately) |
| Suggested retail price | ¥105,000 (sold separately) | ¥87,000 (sold separately) |
Table 2: Specification comparison between the EF-S 15–85mm f/3.5–5.6 IS USM and the EF-S 17–85mm f/4–5.6 IS USM
