Photo 1: EF200-400mm f/4L IS USM Extender 1.4x
This month's technical report presents the EF200-400mm f/4L IS USM Extender 1.4x (Photo 1).
We revamped four lenses in our EF super-telephoto lens series — the 300mm and 400mm in August 2011 and the 500mm and 600mm in May 2012 — to satisfy professionals and high-end amateurs. This product was developed with the aim of going one step beyond these lenses.
This lens is a super-telephoto lens with a built-in extender that has been newly designed so that one lens can cover a wide variety of shooting conditions and scenes. The extender switch lever lets users quickly switch the focal length range between 200-400mm and 280-560mm in one operation.
The lens carries a combination of fluorite and UD lens elements to deliver the image quality demanded of the super-telephoto lens series while also covering a focal length range of 200mm to 560mm with just one lens.
This high-power zoom lens is further equipped with superb operability alongside image stabilization functionality, reliable water and dust protection, and excellent durability.
The design carries forward the super-telephoto lens series' design concept and sensibility suitable for a flagship model while aiming for a high-grade feel and presence. The lens silhouette, which tapers from the front toward the mount, expresses the beauty of converging light. Each part has been expressly designed so that photographers can give their full attention to the shot. In keeping with this, the frequently used zoom ring has been placed in front of the focus ring (Figure 1).
The following sections describe the lens's main features.
Feature 1 - 200-560mm focal length range and high image quality of full-frame pictures
The lens's optical system achieves the high image quality suitable for a super-telephoto lens, despite being a zoom lens, as well as provides image stabilization functionality and a built-in 1.4x extender for a completely new super-telephoto zoom lens. The lens is arranged with 25 elements in 20 groups. When the built-in 1.4x extender is in use, the lens consists of 33 elements in 24 groups (including one rear filter element). The built-in extender itself is organized with eight elements in four groups (Figure 2).
One fluorite lens element and one UD lens element are used in the first lens group and three of the four elements in the focusing lens group are UD elements. The inclusion of these elements drastically reduces the occurrence of chromatic aberrations that tend to appear as color fringing around subject edges, giving high-quality images with excellent resolution and contrast. These elements also help the lens deliver high image quality when the built-in extender is in use (Figure 3).
The inner focusing system is provided by the third lens group (elements 11 through 14) and image stabilization by the fifth lens group (elements 17 through 19), which shifts in parallel.
The biggest feature of the lens, the built-in extender, provides optimal optical characteristics over the entire focal length range. It is placed by making space within the sixth lens group in the lens's rear fixed lens groups. The protrusion at the rear of the lens is used to house the built-in extender's optics when not in use.
Optimizing the lens arrangement and coatings virtually eliminates ghosting and flaring and achieves an excellent color balance. To cut ghosting caused by light sources within the frame, we used a subwavelength structure coating (SWC) on the front surface of the tenth lens group.
A fluorine coating is applied to the front and rear lens surfaces (not including the filter glass) that are exposed to the atmosphere so that any dust or contaminants on the lens surfaces can be easily wiped off with a dry cloth.
The lens is also designed to minimize color fringing when used not only with the built-in extender but also with external extenders.
The minimum focusing distance is two meters, regardless of the zoom position or whether the built-in extender is used.
Feature 2 - Built-in extender
As described in the introduction, photographers can switch the lens's focal length range between 200-400mm and 280-560mm in one operation with the extender switch lever (Note 1).
Note 1: Depending on the EOS camera model used, there are some limitations on the switching operation of the built-in extender. Please refer to your user manual and other references before using the built-in extender.
The built-in extender switching controls have been positioned for ease of use without interfering with the normal shooting operations of focusing and zooming (Figure 4).
The optical features of the built-in extender are as follows.
Typically, most lenses with built-in extenders insert the extender optics at a position where the light rays are travelling in parallel within the lens so that the overall lens length does not change. This is the method used in Canon's interchangeable lenses for commercial and broadcast video cameras.
Because of the different lens type in this case, however, it was difficult to find space to store the extender's optics and to design a mechanism to insert the optics, as the position of the afocal optics coincides with position of the focus ring, switch panel, and other controls.
Consequently, in view of operability, the extender optics were inserted in a location at the rear of the lens so that the switching controls are in a position that the hand can immediately reach while not interfering with the normal shooting controls.
But just inserting an external extender's optics (which are negative power optics (Figure 5-(2)-1)) as a rear convertor in a position where the light forms an image (converges) on the image plane (Figure 5-(1)) would result in extending the lens's back focus and overall length (Figure 5-(2)-2).
Therefore, we engineered the optics by inserting a positive power lens group (Figure 5-(3)-1) so the light rays about to focus on the image plane would converge and focus in front of the image plane (Figure 5-(3)-a).
This is followed with a negative power lens group (Figure 5-(3)-2) that sharply bends the light rays outwards and moves the position of the main focus point (Figure 5-(3)-3) forward (toward the subject). This arrangement extends the focal length and converges the focus on the image plane (Figure 5-(3)-b).
This arrangement also avoids extending the overall lens length because the positive power lens group converges the light somewhat so that the bundle of light rays incident on the negative power optics is smaller / narrower.
Thus, the workings of this combination of positive and negative optics make it possible to extend the focal length without changing the overall lens length.
Feature 3 - Superb image stabilization (IS) function
The lens has a shift-type image stabilizer that moves the fifth lens group perpendicular to the optical axis.
The lens has a specially designed slim IS drive unit. The IS drive unit uses an ultra-low friction mechanism for its internal sliding parts by means of rolling friction with conventional rolling balls. The further optimization of the component arrangement, along with the incorporation of our store of technology from our past IS lens series, delivers excellent image stabilization performance and enables the unit to be slimmer. The slimmer unit also helped fit in the built-in extender.
The IS controls are optimized for the IS unit's structure and characteristics. The stabilizer achieves image stabilization equivalent to four stops faster in shutter speed (at a focal length of 560mm, the built-in extender set to 1.4x, and using an EOS-1D X) (Note 2).
In addition to IS modes Mode 1 and Mode 2, Mode 3 is designed to work with sports photography.
Note 2: Measured in accordance with CIPA (Camera & Imaging Products Association) standards.
Feature 4 - Excellent reliability / durability and operability
In the lens barrel design, we did everything to reduce its weight while ensuring its strength. We used very precise simulations to verify the precision of each lens element (Figure 6).
We made extensive use of magnesium alloys for the main components.
Next, we added waterproofing and dust-proofing to prevent moisture and dust from infiltrating the lens and making it possible to shoot in harsh conditions. Waterproofing and dust-proofing was used around the built-in extender's switching controls and around the switch panel, the mount section, the drop-in filter, and all control rings.
This lens includes the following functions also found on previous super-telephoto lenses.
- AF stop buttons placed at the front of the lens to stop autofocusing at specific positions
Pressing an AF stop button while autofocusing will pause the autofocusing. With the shutter button held down halfway, releasing the AF stop button will resume autofocusing.
- Power focus mode for smooth focusing shifts
To use power focus (PF), set the focus preset switch to OFF and set the focus mode switch to PF. After this, turning the playback ring will shift the focus at a constant speed. This is a useful function for focus shifts while recording movies.
By changing the control angle of the playback ring, the user can select between two focus-shift speeds.
- Focus preset function quickly returns the lens to a preset focus position
The focus preset function can be used in the AF, PF, and MF focus modes.
By turning the playback ring either left or right, the lens will move to the preset focus position. After turning the playback ring, it is possible to release the shutter regardless of any autofocusing. However, when shooting movies on the EOS-1D X, EOS 5D Mark III, or the EOS Kiss X6i, X7i, or X7* and the focus mode switch is in the PF position, the focus will shift at a slow, constant speed. By changing the control angle of the playback ring, the user can select between two focus-shift speeds.
[Japan: EOS Kiss X6i, Americas: EOS Rebel T4i, Europe/Asia/Oceania: EOS 650D]
[Japan: EOS Kiss X7i, Americas: EOS Rebel T5i, Europe/Asia/Oceania: EOS 700D]
[Japan: EOS Kiss X7, Americas: EOS Rebel SL1, Europe/Asia/Oceania: EOS 100D]
In addition to these functions, the lens achieves fast autofocusing due to inner focusing, a ring USM drive, a high-speed CPU, and an optimized AF algorithm. It also has a full-time manual focus mechanism.
A security slot for attaching an anti-theft security cable is provided under the cover of the orientation locking knob for the tripod mount. The lens comes bundled with the drop-in gelatin filter holder 52 (WII). The tripod mount shape is the same as that on the EF500mm/600mm f/4L IS II USM lenses.
Other included accessories are the 200-400 lens case (Photo 2), the ET-120 (WII) lens hood (Photo 3), the E-145C lens cap (Photo 4), the E lens dust cap, and the B lens wide strap.
The EF200-400mm f/4L IS USM Extender 1.4x is a high-quality, highly durable, easy-to-use lens that is sure to satisfy because its built-in extender provides an especially wide focal length range for the super-telephoto lens series.
Given the lens's features, we expect photographers already familiar with super-telephotos will make use of this lens in demanding conditions where the subject cannot be approached as close as one would like and where not a lot of equipment can be taken, such as sports or nature photography. We hope many of these people will become users.
We will continue to work on developing new lenses that serve various needs and endeavor to get closer to the ideal lens.
|Function||EF200-400mm f/4L IS USM Extender 1.4x|
|Built-in extender||At 1x||At 1.4x|
|Focal length / F number||200-400mm f/4||280-560mm f/5.6|
|Lens construction||25 elements in 20 groups||33 elements in 24 groups|
|Aperture blades||9 (circular aperture)|
|Min. focusing distance||2m|
|Max. magnification||0.15x (at 400mm)||0.21x (at 560mm)|
|Filters||Drop-in 52 (WII) series|
|Max. diameter x length||128 x 366mm|
|Weight (including tripod mount)||Approx. 3,620 g|
· Lens length is the measurement from the mount surface to the tip of the lens.
· All data were measured in accordance with Canon standards.