Canon EOS-10DCanon revamps their hugely popular D60 SLR, with ahost of improvements and a dramatic price cut!<<Viewfinder :(Previous) | (Next): Exposure & Flash>> Page 5:OpticsReview First Posted: 02/27/2003 |
Optics
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As with other digital SLRs I've tested, there's not a great deal to report in the "optics" section of this review. The Canon EOS 10D accepts all standard EF-series Canon lenses, a collection that includes roughly 56 currently produced models, and more than 100 released since the series began in 1987. Key features of the Canon EF lens series are models with the exceptionally fast, silent "ultrasonic" focusing mechanism ( a coreless motor built into the lens body itself), and the exceptional range of optically stabilized models that permit hand-holding way beyond light levels that would normally require the use of a tripod.
Like most digital SLRs, the sensor in the EOS 10D is smaller than a 35mm film
frame. This means that the "effective" focal length of your lenses
will be 1.6x their normal values on 35mm cameras. Just to be clear, nothing's
changed about the lenses or their behavior, it's just that the CMOS sensor is
effectively cropping a smaller area out of the lens' coverage circle. The net
result is that shooting really wide angle photography is tough with digital
SLRs, the 10D included. At the other end of the scale though, it's like having
a 1.6x teleconverter on your lenses with no cost in light loss or sharpness.
Thus, a 300mm telephoto has the same "reach" as a 480mm on your 35mm
film camera. And of course, a f/2.8 300mm is a lot cheaper than a f/2.8
500mm! The net of it is that a 31mm focal length has the same angular coverage
as a 50mm lens on a 35mm SLR, and the common 16-35mm zoom lenses have a range
equivalent to 25.6-56mm on film cameras.
When I tested the original D30, I asked Canon for a fair range of lenses to
test as well. (My favorite was the 100-400mm optically-stabilized zoom, equivalent
to a 160-640 mm zoom on a 35mm camera. Great fun at my son's soccer game, and
the optical stabilization was really a dream to use, worked extremely well.)
The surprise contender was their 24-85mm lens (shown above), equivalent to a
38-136mm. It showed some bad coma in the upper left-hand corner of the frame
when wide open, but outperformed a costly 28-70mm L-series lens overall. The
hands-down winner for corner to corner sharpness though was a 100mm f/2.8 fixed
focal length macro lens. I've found that digital cameras really show up the
least lens defects, so getting good glass to use with your high-end SLR is very
important. That said, the relatively inexpensive 24-85mm EF-series zoom mentioned
earlier turned in a surprisingly good performance. (For my testing of the 10D,
I had on hand the 100mm macro lens again (for res-target shots, to insure maximum
sharpness), the L-series 28-70 f/2.8, and a sample of their new L-series 16-35mm
f/2.8. I haven't done any definitive lens testing of the new 16-35mm yet, but
have to say it's a very sweet little lens. - More compact than I'd expected
for it's f/2.8 constant aperture.)
Autofocus System
This is an area where I'm probably least qualified to comment, given the relatively
small amount of time I spend in "live" shooting situations with professional-grade
SLRs, but my impression of the 10D's AF system was very favorable overall. The
10D has an autofocus system with seven sensors, arrayed in a cross pattern in
the center of the frame. You can manually select which of these you want the
camera to pay attention to (handy for off-center subjects), or you can let the
camera decide. When it's operating in automatic AF mode, it will use the sensor
corresponding to the part of the subject closest to the camera. When shooting
in full Automatic exposure mode, the camera selects either One Shot or AI Servo
AF focus modes, depending on the state of the subject. (You can also set the
camera to do this in other modes, by selecting the AI Focus AF mode.) If the
subject remains stationary, the camera remains in One Shot AF mode. However,
if the subject begins to move, the camera automatically switches over to AI
Servo AF and begins tracking the subject as it moves. This is a handy feature,
letting you automatically track moving subjects without having to manually adjust
the focus mode. In any of the Creative Zone modes, you can set the AF mode to
One Shot, AI Focus AF, or AI Servo AF. The 10D employs a technology that Canon
calls Predictive AF, which means that if the subject approaches or retreats
at a constant rate, the camera can track the subject and predict the focus distance
before the image is captured. Thus, you get the correct focus exactly at the
moment of exposure. The AF system's low light limit is EV 0.5, which combined
with the AF assist lamp, provides excellent focusing in dim lighting conditions.
The AF system is one of the areas in which the EOS-10D has been significantly
upgraded relative to the system used in the D30 and D60 before it. Besides the
expansion to 7 AF zones, the new system is a good bit faster as well. Canon
rates the performance of their AF systems by the point at which they cease to
be able to track an object moving at a constant speed toward the camera, using
a given lens. - The closer an object gets, the more rapidly the focusing point
will change, so minimum focusing distance at a constant approach speed does
provide a good measure of AF speed. Using Canon's EF 300/3.8 IS USM lens as
the basis of comparison, the EOS-10D can track an object moving at 30 mph (50
kph) down to a minimum distance of 26.4 feet (8 meters). Under the same conditions,
the D60 would lose focus tracking at a distance of 39 feet or 12 meters. Thus,
by this measure, the EOS-10D's AF system is half again as fast as that of the
D30 and D60 before it.
The above notwithstanding, I did encounter a few situations where the 10D's
autofocus had problems, delivering out-of-focus images. Significantly though,
these were all situations where I'd manually selected an AF point, wanting to
set focus on a specific part of the subject. (One of Marti's eyes, for example,
in my standard "Outdoor Portrait" shot.) What I suspect happened was
that the AF sensor I'd chosen ended up over a low-contrast region (for example,
Marti's cheek) as I pressed the shutter, giving the camera little to judge focus
with. The AF point indicator I'd chosen would flash to indicate that the camera
was focusing, but I was given no sign that the focusing hadn't been successful.
Operator error, in other words. As far as I can tell, I never experienced a
focus failure when using the camera in any of it's automatic focusing modes.
The moral of this tale is to exercise particular caution when you're working
with a manually-selected AF point, to insure that you're giving the camera something
usable to focus on.
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