Camera Accessories

If you watched any broadcasts of the Beijing Olympics you probably saw photographers with Canon's large, ultra-fast telephoto prime lenses, which are purpose-designed to provide pin-sharp images in low light levels. The new EF 200mm f/2L IS USM is one such lens, offering an outstanding combination of a 200mm focal length with a maximum aperture of f/2.

You need a lot of glass to provide such a bright image at a long focal length and the 200mm f/2L's front element has a diameter of close to 100 mm. In fact, the combination of all that glass and excellent build quality - not to mention a high level of technological sophistication - account for most of the high price tag affixed to this lens.

As befits a professional lens, Canon has made extensive use of dust- and moisture-resistant sealing throughout the lens barrel and includes a rubber ring around the camera mount. All told, it's a complex and very substantial handful, with an overall length of 208 mm - excluding the lens hood - and weighing 2.52 kilograms. It's so big it comes in its own 200-series suitcase, which has a contoured interior and Velcro strap for securing the lens in place.

Side view of the EF 200mm f/2L IS USM lens without lens hood and end cap. (The tripod bracket is not shown.)

The 200mm f/2L lens consists of 17 elements in 12 groups with one fluorite and two UD (Ultra-low Dispersion) lens elements to minimise chromatic aberration and provide natural looking contrast. The built-in Optical Image Stabiliser claims to provide up to four stops of stabilisation correction. Canon's Ultrasonic Motor (USM) technology is provided for smooth, quiet autofocusing and the new lens features improved AF algorithms for better performance.

 
The diagram above shows the optical components of the 200mm f/2L lens. The fluorite element is shown in pink with the UD elements coloured blue. The large silver collar mid-way along the lens is the ultrasonic motor.  The image stabiliser is indicated by the green toroidal circuit board towards the right hand end. Mid-way between the USM and the IS assembly is the electro-magnetic diaphragm. (Source: Canon.)

The lens barrel is made from magnesium alloy and finished in Canon's 'white' enamel (which is actually closer to beige in colour).  A stainless steel camera mounting plate steps out to a narrow barrel that carries the drop-in filter drawer, which accepts 52mm filters. Sliding switches for swapping between auto and manual focusing are located further down, along with a focusing distance limiter, which can be used to minimise hunting in low light. (For details see the Handling section, below.)

The barrel steps out again to hold a rotating tripod bracket collar, which is non-removable. It sports a screw clamp that also allows users to switch the camera orientation quickly between horizontal and vertical, with click stops at 90-degree intervals. Strap mounting lugs on either side of the tripod collar allow a carrying strap to be attached.

Forward of the tripod collar is a distance window with indices in metres and feet, ranging from 1.9 metres to infinity. A small depth-of-field scale is engraved just rear of the window with indices for f/32 and f/16 (wider apertures have such shallow depth of field they can't be shown). Positioned down the left side of the barrel from the distance window are three sliders. The top two cover the built-in stabiliser's settings while the lower one handled focus pre-set.

Two stabiliser modes are provided. Mode 1 operates in all directions and is used for general photography. Mode 2 only stabilises in one direction and is used for panning. The stabiliser mechanism can detect the camera's orientation and will switch off stabilisation in the direction of the panning movement. Below the stabiliser mode switch is a slider for turning stabilisation on and off. Interestingly, unlike the systems used in cheaper lenses, in Canon's pro lenses, the stabilisation system can recognise when the camera is tripod-mounted and turn stabilisation off - except for compensating for any 'mirror slap' that might affect image sharpness.

Canon claims the stabiliser can cut four EV in shutter speed off normal shooting speeds. To achieve this, you would have to reduce the normal 'rule-of-thumb' shutter speed of 1/200 second to 1/25 second. We came close to that, getting a sharp image at 1/30 second (shown below) with the indoor portrait shown below. (But most outdoor shots were taken at shutter speeds of 1/1000 second or faster.)

 
Indoor shot: 1/30 second at f/4.6; ISO 640.

Further down is a focus pre-set slider, which has three positions: off, on and beeper. The focus preset can be used in both AF and MF modes and enables you to pre-set a specific focus distance. Simply set the switch to on and half-press the shutter button to find focus. Then press the focus preset button. If you've set the switch to beeper, you will hear an audible sound each time focus is achieved.

Forward along the barrel is a wide rubber-coated focusing ring with ridges to provide a firm grip. In front of it is a 'playback' ring that is used to recall the pre-set focusing distance. The lens barrel flares out slightly in front of the playback ring to accommodate a second, narrower ring with four AF stop buttons arranged at 90 degree intervals around its diameter. These buttons are used to temporarily pause (and release) autofocusing.

A narrow channel for attaching the lens hood (supplied) is located in front of the AF button ring. The lens hood is a metal cylinder with a matte inner surface, which attaches via a locking knob and reverses onto the barrel when not in use. Covering it is the E-145B lens cap, a cylindrical leather 'bag' with a drawstring top and solid padded base that slips over the lens, covering the tripod bracket. It is secured by drawstrings close to the camera body and a strap across the base assists with quick removal.

The front element of the lens is recessed approximately 25mm into the lens barrel. Roughly half of the depth of this recess is screw-threaded, but we haven't a clue why because the filters slot in towards the back of the optical path. The remainder is hard matte black rubber. The EF 200mm f/2L IS USM lens is compatible with Canon's EF 1.4x II and EF 2x II extenders. 

Handling
We tested the 200mm f/2L lens on two camera bodies: a Canon EOS 5D and a 400D. On the 5D body it was a comfortable fit and nicely balanced - even with the large hood attached. It should be equally at home on any of Canon's professional EOS bodies. All-up weight with the 5D body is around 3.5 kilograms.

The much lighter 400D body was slightly unbalanced and we had to use shutter speeds faster than about 1/800 second for hand-held shots to ensure sharp images. Slower shutter speeds were possible when the lens was tripod mounted. Although most photographers will attach a tripod or monopod to get the most from this lens, it is actually quite usable hand-held (although the tripod mount does get in the way at times). This is largely thanks to the stabilisation system and the overall balance of the lens on the 5D. It's easy to change the orientation of the camera without having to remove it from a tripod by simply unlocking the tripod collar.

Not unexpectedly, focusing can be challenging at wide lens apertures because even small movements are magnified by the lens. However, as mentioned, Canon provides plenty of focusing options. You can engage or disable the AF system by sliding the AF/MF switch and constrain the AF range with the focus limiter.  Two options are provided: 1.9 metres to infinity and 3.5 metres to infinity. You can also use the focus pre-set system or override autofocusing with either the AF stop buttons or by simply turning the focusing ring.

Autofocusing was extremely fast, almost silent and very accurate, thanks to the USM technology. AI Servo tracking of moving subjects capitalised on the system's accuracy and speed.  The bright viewfinder image made focusing manually a viable option. You can switch from auto to manual by simply turning the focusing ring (manual focusing automatically overrides AF). The focusing ring moves through just under three quarters of a turn as you shift focus from 1.9 metres to infinity.

Manual focusing was very smooth and the ring offers just enough resistance to make setting precise focus easy. The focus limiter was straightforward to use and definitely speeded up autofocusing. Pre-setting a focus distance was also straightforward and quite effective when shooting moving subjects.

Performance
Imatest showed the test lens to be capable of very high resolution, with peak performance between f/2.8 and f/8 and a gradual decline from f/16 on, where diffraction limiting takes effect. Differences in centre and edge resolution were detected but by f/8 they were irrelevant and even with the lens wide open it was difficult to see any edge or corner softening in tests shots.

The graph below shows the results of Photo Review's tests with the EOS 5D camera body. We weren't able to run Imatest tests with the EOS 400D body because we don't have enough distance leeway in our testing set-up to handle its equivalent focal length (320mm in 35mm format).  

Lateral chromatic aberration was vanishingly small and ranged between 0.004% and 0.008% of distance to corner throughout the lens aperture range. The border between 'negligible' and 'low' is 0.04% which is an order of 10 higher than the most common reading in our tests. We found no evidence of coloured fringing in test shots.
Flare was handled particularly well, with minimal loss of contrast in strong backlighting and no flare spots.

Vignetting was only just visible in test shots of blue sky with the 5D body at apertures larger than f/4. It was barely noticeable in test shots with the 400D body at f/2. No rectilinear distortion was found in any test shots.  Bokeh was consistently attractive, particularly at f/2.

The shallow depth-of-field at f/2 requires good shooting technique to ensure sharp images at shorter distances with this lens. But the image quality when you catch the moment precisely more than justifies these relatively minor challenges.

IMATEST GRAPHS

SAMPLE IMAGES

Hand-held shot in dim lighting, taken with EOS 5D; ISO 640, 1/330 second at f/2.

Hand-held shot in bright light, taken with EOS 5D; ISO 400, 1/1600 second at f/2. Note the attractive bokeh (out-of-focus blur).

Hand-held shot in bright light, taken with EOS 5D; ISO 250, 1/800 second at f/3.2. Note the slight corner vignetting.

Vignetting is no longer evident at f/10.

Distance shot with EOS 5D; ISO 100, 1/395 second at f/9.

Shot from the same vantage point taken with the EOS 400D; ISO 100, 1/1600 second at f/5.

Shot taken with the EOS 400D on a tripod; ISO 100; 1/500 second at f/4.

Contre-jour shot taken with EOS 400D; ISO 100; 1/500 second at f/5.

Picture angle: 12 degrees diagonal (on full-frame sensor camera)
Maximum aperture: f/2.0
Minimum aperture: f/32
Lens construction: 17 elements in 12 groups
Lens mount: Canon EF
Optical Stabilisation: Yes; two modes
Minimum focus: 1.9 metres
Maximum magnification: 0.12x
Diaphragm blades: 8
Filter size:  52mm (drop-in gelatin filter holder)
Dimensions (Diameter x L): 128 x 208 mm (maximum lens length)
Weight: 2.52 kg