Canon EOS D60Canon updates their D30 Semi Pro SLR with a 6 megapixel sensor and other improvements, and sets a new low-price point in the process!<<Optics :(Previous) | (Next): Shutter Lag & Cycle Time Tests>> Page 6:Exposure & FlashReview First Posted: 2/22/2002 |
Exposure
As you'd expect, the EOS D60 provides really complete exposure control. Standard
exposure modes include the usual Program, Aperture-Priority, Shutter-Priority,
and full Manual, as well as some "Image Zone"
(scene-based preset) modes, and one of the most unique (and uniquely
useful) modes I've yet seen, an Automatic Depth-of-Field mode. The
"Image Zone" exposure modes include Portrait, Landscape, Macro, Sports,
and Night Scene modes. These modes preset a variety of camera parameters to
make it easier for non-expert photographers to achieve good exposures in a variety
of standard shooting situations. The full Auto mode takes over all camera functions,
making the D60 into a very easy to use point and shoot camera, albeit a very
capable one. In a concession to the D60's smaller (and therefore more noise-prone)
sensor pixels, the D60's maximum ISO speed is 1000. (Default ISO is 100, other
options are 200, 400, and 800.)
As noted, I was most impressed with the Automatic Depth-of-Field mode. This
mode uses all three autofocus zones to determine the amount of depth in the
active subject area. Once it has determined the range of focusing distances
present across the three zones, it automatically computes the combination of
aperture and shutter speed needed to render all three zones in sharp focus.
This struck me as a remarkably useful feature, even for professional photographers.
In many situations, you want to keep several subjects in focus, while at the
same time trying for the highest shutter speed (largest aperture) that will
permit that. In practice, faced with such situations, I've usually resorted
to just picking the smallest aperture feasible and hoping for the best. With
the D60's A-DEP mode, the camera takes the guesswork out of this process and
gives you the fastest shutter speed it can manage while still keeping things
in focus. (In playing with this, I was often surprised by how large an aperture
in fact would work. I frequently would have chosen a much smaller aperture to
stay on the safe side.)
I also liked the way Canon implemented the automatic exposure bracketing on
the D60. You can set the total exposure variation (across three shots) at anywhere
from +/- 1/3 EV all the way up to +/- 2 EV. The nice part is that the automatic
variation is centered around whatever level of manual exposure compensation
you have dialed in. Thus, you could set positive compensation of 0.7EV, and
then have the camera give you a variation of +/- 2/3 EV around that point.
Speaking of exposure compensation, the D60 also lets you specify the step size
for EV adjustments. The default is a step size of one-half EV, but you can set
an increment of one-third EV unit via the LCD menu system. (Frankly, we've always
found that one-third EV compensation is just about ideal for digicam. One-half
EV steps are just too broad to set critical highlight exposures accurately.)
I
really liked the amount of information the D60 gives you about its exposure,
not only in terms of the settings it's using, but in the form of feedback on
how pictures you've captured turned out. You can select an "Info"
display mode when viewing captured images on the rear-panel LCD screen, which
produces the display shown at right. Notable here is that you not only can see
all the exposure parameters, but you get excellent feedback on the tonal range
of the image itself. One form of feedback is the histogram display at upper
right, which shows how the tonal values are distributed within the image. Histogram
displays are useful for directly seeing how the overall exposure turned out
in an image, but I've found them to be of limited usefulness for making critical
judgments about highlight exposure.
Digital cameras need to be exposed more or less like slide film, in that you
need to zealously protect your highlight detail. Once you've hit the limit of
what the sensor can handle, the image "clips" and all detail is lost
in the highlight areas. The problem is that it's quite common for critical highlights
to occupy only a very small percentage of the overall image area. Because they
correspond to such a small percentage of the total image pixels, the peak at
100 percent brightness can be very hard to distinguish in the histogram display.
To handle such situations, the D60 blinks any pixels that are 100 percent white
on its screen, alternating them between black and white. This makes localized
overexposure problems leap out at you, making it very easy to control the critical
highlight exposure precisely. (The sample image shown in the display above is
a pathological example, chosen to show how the feature works. In practice, you'd
probably never overexpose an image that badly.)
Besides
the above-mentioned exposure information and feedback, the D60's playback options
include a thumbnail index display, normal full-frame viewing of captured images,
and a zoomed view, as shown at right. There's also a "jump" mode,
activated via the button of that name on the rear panel of the camera. Jump
mode lets you very quickly move through images stored on the memory card, jumping
9 shots at a time.
Another feature deserving comment is the D60's separation
of the autoexposure and autofocus lock functions. In consumer-level digicams,
half-pressing the Shutter button locks exposure and focus simultaneously. You
can use this to deal with an off-center subject by pointing the camera at the
subject, locking exposure and focus, and then reframing the picture before finally
snapping the shutter. The only problem is that you sometimes need to perform
a more radical recomposition of the subject in order to determine the proper
exposure. For instance, you may want to zoom in on the subject, grab an exposure
setting, and then zoom back out before taking the picture. Situations like that
require locking the exposure independently of the focusing, and the D60 provides
for just such eventualities by way of a separate AE lock button on the back
of the camera, right under your right thumb. A very handy feature indeed, for
those times you need it.
Low Light Capability
Low light shooting looks to be a real strong point of the D60, with new
noise-reduction algorithms introduced for the first time. The D30 was an excellent
low-light performer, but the D60 looks to be even better, or at least more efficient
at the same level of performance.
When operating the camera in full-manual exposure mode,
the D60 offers a Bulb exposure setting for very long exposures. Normally, exposure
times are limited to a maximum of 30 seconds in Aperture- or Shutter-Priority
modes, but in Manual mode, you can expose for as long as 999 seconds by selecting
Bulb mode and holding down the Shutter button for as long as you want the shutter
to remain open. Obviously, 999-second exposures aren't a practical reality.
Sensor noise will totally swamps the signal long before that point is reached.
The D60 does have some new tricks up its sleeve in the long-exposure department
however.
One of the first things I noticed in comparing the D60's custom function menu
options against those of the D30 was that the Noise Reduction option was missing.
Chuck Westfall of Canon USA confirmed that this was the case, saying that the
D60 incorporated new noise reduction algorithms that no longer needed a user
option to turn them on or off. A little explanation here would might be in order.
A full discussion of image sensor noise is *way* beyond the scope of this review,
but the simple story is that the most obvious and objectionable noise we see
in long digicam exposures is so-called "fixed pattern" noise, caused
by variations in "dark current" between sensor pixels. "Dark
current" is just what it sounds like: Current (a signal) that appears even
when the sensor isn't being exposed to light. When you look at a long time exposure
shot with a digital camera, you'll often see very bright pixels, where minor
manufacturing defects have resulted in unusually high "dark current"
levels. Often called "hot pixels," these flecks of color are very
distracting visually.
The normal way to deal with hot pixels is to take an exposure with the camera's
shutter closed, immediately after shooting the subject. If this "dark frame"
is exposed for the same time as the subject was, you can largely eliminate the
hot pixel problem by subtracting the dark frame information from the actual
exposure. In practice, this works fairly well, but has the disadvantage that
you have to wait for the dark frame exposure to be taken, requiring an appreciable
amount of time in the case of long time exposures. (If you shot a 1 minute exposure
for the photo itself, you'll have to wait another minute for the dark frame
exposure to be made.)
The original D30 used dark-frame noise reduction, as do most other high-end
digicams on the market. The D60 appears to be doing something very different
though, as there's very little delay between the end of the primary exposure
and the writing of the image file to the memory card. There's clearly no "dark
frame" exposure involved. I suspect that this advanced noise reduction
processing in the D60 is another consequence of the "active pixel"
CMOS technology Canon developed for the D30 and D60. Having active circuitry
associated with each pixel in the sensor array allows lots of fancy processing
that would be impossible otherwise, and it looks like Canon's new noise reduction
system takes advantage of this.
However they do it, Canon's new noise reduction system in the D60 is astonishingly
effective. Prior to receiving the first prototype D60s to work with, Canon USA
told me that they thought the D60's noise reduction was at least somewhat more
effective than that of the D30. I didn't pay much attention to the low light
test images from the prototype cameras I worked with, since noise performance
often improves as a camera moves from prototype to production. When I finally
looked closely at the results from the production D60 and compared them to those
from the D30, the difference was so dramatic that I frankly checked the image
files three times to make sure I hadn't made some mistake: The D60's noise levels
4-5x times lower than those of the D30s, even with an exposure time that
was 4x longer! (My D30 low light tests were shot with the 28-70mm f/2.8 lens,
while the D60's were shot with the 24-85mm f/3.5, and I ended up exposing the
D60's shot more, producing a brighter image.) The cropped shots below give some
idea of just how radically improved the D60's low light noise levels are over
those of the D30: These are crops of the same swatch of the MacBeth chart in
the Davebox test target, shot at a light level of 0.67 lux, the lower limit
of my low-light test. (This is really dark, a full four stops darker than typical
city street lighting at night.)
|
Image Noise Standard Deviations |
||
|
Camera> |
D30
|
D60
|
|
(Channel) |
 2.74 |
|
|
Luminance
(RGB) |
||
|
Red
|
 3.59 |
 0.59 |
|
Green
|
 2.88 |
 0.72 |
|
Blue
|
 3.77 |
 0.92 |
Overall, this is a remarkable achievement in sensor noise reduction. If your photography calls for any amount of after-dark photography with long bulb exposures, the D60 is far and away the best camera I've seen for that purpose.
Flash
The EOS D60's built-in flash was very effective in my tests. The limited information Canon provided with the unit didn't include a guide number rating for the internal flash, but the D30's carried a guide number of 39 feet (12 meters) at ISO 100. This suggests a range of about 14 feet at f/2.8, a result that agreed well with my testing of the D60. I was also impressed by how accurate flash exposure was, as it didn't seem to be fooled by unusual subjects such as the light-on-dark of our Davebox flash range test target. (Some cameras have a tendency to overexpose this due to the dark background.) It's hard to overstate how easy it was to get exceptional results with it and in fact, I felt I really had to go out of my way to get a bad exposure.
The D60 gives you a great deal of control over flash exposure, allowing you to adjust flash and ambient exposure independently of each other, in one-half or one-third EV increments. This makes it very easy to balance flash and ambient lighting for more natural-looking pictures. The camera also boasts a custom function for "Auto Flash Brightness Reduction" that is particularly useful when using the flash for fill illumination in daylight shooting conditions. With this mode enabled, if the ambient light is above a certain level, the camera will assume you're using the flash in a "fill" mode, and will automatically back off its intensity a bit, to avoid washing out the natural lighting.
Another nice touch was the Flash Exposure Lock button, which fires the flash under manual control before the actual exposure, to determine the proper exposure setting. This struck us as very handy, akin to the more conventional autoexposure lock function for handling difficult ambient lighting conditions.
As was the case with the D30, several of the more impressive features of the Canon flash system depend on the dedicated 550 EX speedlight. (While a number of Canon speedlights will work just fine with the D60, their previous top-end 540EX unit apparently does not, so you'll need the new 550EX to fully tap the D60's flash potential.) Among these are true FP (focal plane) flash sync, flash exposure bracketing with external flash units, and flash modeling. FP sync requires a flash unit to provide uniform light output for a relatively long period of time, long enough for the focal plane shutter curtain to fully traverse the "film" plane (sensor plane in the case of the D60). On the D60, this requires a flash duration of 1/200-second. Uniform, long-duration flash pulses like this permit use of shutter speeds as high as the 1/4,000-second maximum that the D60 is capable of. This can be invaluable when you want to exclude ambient light from the exposure.
Here's the rundown on Canon Speedlights and their compatibility with the D60:
| Speedlight Model | On-Camera Capability | E-TTL Wireless Compatibility |
| 550EX | All | Master or Slave |
| 480EG | External auto plus manual operation | None |
| 540EZ | Manual operation only | None |
| 430EZ | Manual operation only | None |
| 420EX | All | Slave Only |
| 420EZ | Manual operation only | None |
| 380EX | All | None |
| 220EX | All | None |
| 200E | Not Compatible | None |
| 160E | Not Compatible | None |
| MR-14EX Macro Ring | All | Master Only |
| MT-24EX | All | Master Only |
| ST-E2 transmitter | E-TTL, attach to camera | Master Only |
| Non-dedicated shoe-mount units | Manual operation only | n/a |
| Studio strobe packs | Manual operation only, connect via threaded PC sync socket on camera body | n/a |
You'll note the references to "E-TTL remote" capabilities in the table above: Canon's Speedlight system permits TTL flash metering with multiple remote units, and even allows you to set differential power ratios between the slaved units, over a six-stop flash exposure range.
I explained Flash Exposure Bracketing (FEB) and flash exposure compensation
above, so won't review those features in the context of external flash operation.
What does deserve separate comment is the "Flash Modeling" feature
of the 550EX speedlight when used with the D60. With a F550EX connected to the
D60, pressing the camera's depth-of-field preview button causes the speedlight
to fire at 70 flashes per second for about one second. This creates the illusion
of a constant light source for your eyes, letting you preview the lighting on
your subject when the flash fires. VERY handy, and likely to save lots of shoot/check/reshoot
time!
As alluded to above, the "X-sync" speed of the D60 is 1/200-second. (This is the maximum shutter speed that can be used on the D60 when working with a non-dedicated, FP-capable speedlight.) When used with higher-powered studio strobe systems, Canon recommends a maximum shutter speed of 1/60-second or slower, to accommodate the time/intensity profile of such units. Finally, via a custom function menu setting, you can program the D60 to use a shutter speed of 1/200-second in Aperture-Priority exposure mode regardless of ambient light levels. (We guess this is useful, if you know you're going to be hopping in and out of flash mode, but other than a convenient preset for the shutter speed, it's little different than simply using Manual mode to set both shutter speed and aperture.)
A final benefit of the dedicated Canon speedlights is that they carry powerful
autofocus assist illuminators that can extend the range of the built-in AF assist
light of the D60. The AF assist beam on the 550EX is rated as good to about
50 feet(!), vs the roughly 13 feet of the lamp on the D60 itself. The 550EX
illuminator is also much less obtrusive, since it's a near-infrared beam, rather
than the bright white of the krypton bulb on the D60's body. (NOte too, that
the ST-E2 transmitter can also be used for AF assist during non-flash photography,
a handy trick.)
Continuous Shooting Mode
Among digital SLRs currently on the market, the D60 comes in about midway in terms of shooting speed. The Continuous Shooting mode is rated by Canon at three frames per second, a number that matched almost exactly my own tests (which showed a frame rate of 2.94 seconds). This is considerably faster than the 1.5 frames per second of the Fuji S1 Pro, just a hair faster than the 2.86 frames per second of Nikon's D1x, but a good bit slower than the blazing 8 frames per second of Canon's own EOS-1D. Fast enough for you? - You'll have to be the judge of that. Professional sports shooters will doubtless want more (they being a primary target of the EOS-1D), but for most situations, I expect the D60 will be plenty fast enough.
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