Digital Cameras - Canon PowerShot A85 Test Images
|I've begun including links in our reviews to a Thumber-generated index page for the test shots. The Thumber data includes a host of information on the images, including shutter speed, ISOsetting, compression setting, etc. Rather than clutter the page below with *all*that detail, we're posting the Thumber index so only those interested inthe information need wade through it!|
(This is my new "Outdoor" Portrait test - read more about it here.)
The extreme tonal range of this image makes it a tough shot for many digicams, which is precisely why I set it up this way, and why I shoot it with no fill flash or reflector to open the shadows. The object is to hold both highlight and shadow detail without producing a "flat" picture with muddy colors, and the PowerShot A85 handled the challenge pretty well.
The shot at right was taken with a +0.7 EV exposure compensation adjustment, which resulted in moderately bright midtones, and good detail in the strong highlights of Marti's shirt. Though slightly warm, I chose the Auto white balance setting for the main series, though the Daylight setting also produced good results. The Manual setting resulted in a stronger red cast.
Marti's skin tones here are just about perfect, and the very difficult blue flowers in the bouquet are pretty much dead-on. (Many digicams have trouble with this blue, which is in reality a light navy with only hints of purple in it.) The bright red flowers appear more on the pink side, but the strong greens and yellows look good. Resolution is high, and detail is strong in the flower bouquet and in Marti's features. Shadow detail is moderately high, with moderate noise. Overall, a really excellent job.
To view the entire exposure series from zero to +1.0 EV, see files A85OUTBAP0.HTM
through A85OUTBAP3.HTM on the thumbnail index page.
Great resolution and detail, though contrast is slightly high.
Color and overall exposure are similar to the wider shot above, with slightly high contrast. The midtones in Marti's face are just about right, and the highlights of her shirt are nicely under control, but the high contrast leaves the shadows around her eyes a little too deep. Still though, a very good handling of a very tough subject. The shot at right was taken with no exposure compensation adjustment. The A85's 3x zoom lens does a good job of preventing any geometric distortion of Marti's features. Detail and resolution are excellent, with great definition in Marti's face and hair, as well as in the fabric of the green leaves.
To view the entire exposure series from zero to +1.0 EV, see files A85OUTBFACAP0.HTM
through A85OUTBFACAP3.HTM on the thumbnail index
Indoor Portrait, Flash:
Good intensity and coverage with the built-in flash, but an orange cast from the room lighting.
The A85's built-in flash underexposed this shot at the default exposure, but provided fairly even coverage despite the low intensity. I chose a +1.0 EV exposure compensation adjustment for the main shot, as Marti's features were better illuminated. Her shirt looks a little "hot," but highlight detail is still preserved. The strong incandescent lighting in the room results in an orange cast on the back wall, which also spills onto Marti's features and shirt somewhat. Still, overall color is pretty good.
To view the entire exposure series from zero to +1.3 EV, see files A85INFP0.HTM
through A85INFP4.HTM on the thumbnail index page.
Indoor Portrait, No Flash:
Very good color with both the Incandescent and Manual white balances. Image noise is a bit higher than average, and some detail seems lost to noise reduction processing though.
This shot is always a very tough test of a camera's white balance capability, given the strong, yellowish color cast of the household incandescent bulbs used for the lighting. It was a toss-up between the A85's Incandescent and Manual white balance settings, as both produced similar results. The slight warmth of the Incandescent setting looked a little more natural to me, so I chose it for the main example here. (The Auto white balance option resulted in a very strong warm cast.) Skin tones look pretty good, just a little more pink than would be ideal, and the blue flowers in the bouquet are nearly right, very impressive for this shot. The bright red flowers have a stronger pink hue, but the greens and yellows look good. Image noise is higher than average, and the anti-noise processing appears to obscure fine detail in Marti's face. The best exposure was obtained with a +1.0 EV exposure compensation adjustment, which is about average for this shot.
To view the entire exposure series from zero to +1.3 EV, see files A85INMP0.HTM
through A85INMP4.HTM on the thumbnail index page.
High resolution and strong detail, with accurate color.
The A85's Manual white balance produced
the best results here, though the Auto and
Daylight settings also performed well (with
just a slightly warmer color balances). Resolution is very high, and detail
is strong in the tree limbs above the roof, as well as in the smaller
leaf details of the front shrubbery. The brick pattern of the house is
well-defined also. Details are sharp throughout the frame. An excellent
job all around.
Excellent resolution and detail, though a slightly limited dynamic range.
This image is shot at infinity to test far-field lens performance. NOTE that this image cannot be directly compared to the other "house" shot, which is a poster, shot in the studio. The rendering of detail in the poster will be very different than in this shot, and color values (and even the presence or absence of leaves on the trees!) will vary in this subject as the seasons progress. In general though, you can evaluate detail in the bricks, shingles and window detail, and in the tree branches against the sky. Compression artifacts are most likely to show in the trim along the edge of the roof, in the bricks, or in the relatively "flat" areas in the windows.
This is my ultimate "resolution shot,"
given the infinite range of detail in a natural scene like this, and the
A85 performed very well for its four-megapixel class. Fine detail is strong
in the tree limbs over the roof, as well as in the fine foliage in front
of the house, with great definition in the leaf patterns. Details are
also fairly sharp from corner to corner, with less softening in the corners
than I'm accustomed to seeing in digicam photos. The harsh lighting combined
with the A85's slightly high native contrast results in it losing most
of the detail in the bright white paint surrounding the bay window, a
trouble spot for many digicams. Detail is pretty good, though, in the
shadow area above the front door. The Auto white balance setting produced
accurate color, and exposure is about right, though contrast is high.
The table below shows a standard resolution and quality series, followed
by ISO and effects series.
Lens Zoom Range
A typical 3x zoom range.
I routinely shoot this series of images to show the field of view for each camera, with the lens at full wide angle, at maximum telephoto (3x, in this case), and at full telephoto with the digital zoom enabled. The A85's lens is equivalent to a 35-105mm zoom on a 35mm camera. That corresponds to a moderate wide angle to a moderate telephoto. Following are the results at each zoom setting.
Nearly accurate color, though slightly warm. High resolution and a lot of visible fine detail.
This shot is often a tough test for digicams, as the abundance of blue
in the composition frequently tricks white balance systems into producing
a warm color balance. Though just slightly warm, I chose the A85's Daylight
white balance setting for this shot. The Auto
setting resulted in a bit stronger warm cast, while the Manual
setting appeared more magenta (All three results were within the acceptable
range, the A85 generally doing a better than average job of dealing with
this tricky white balance challenge.) The blue background has a few purplish
tints in the darker areas from the warm cast, as do the deep shadows of
the blue robe. Skin tones are pretty good, particularly in the shot captured
with Daylight white balance. Detail is great in the bird wings on the
blue robe, as well as in the necklaces and instrument details, evidence
of high resolution. Details are also sharp, from corner to corner.
A small macro area with excellent detail, but the flash has trouble up close.
The A85 performed well in the macro category, capturing a minimum area
of 2.53 x 1.90 inches (64 x 48 millimeters). Resolution is very high,
and detail is excellent in the brooch, coins, and dollar bill. Details
are very sharp throughout most of the frame, though all four corners are
soft. (Softness in the corners of the frame is unfortunately a very common
failing among consumer digicams in Macro mode.) Color and exposure look
good as well. The A85's flash had trouble throttling
down for the macro area, and overexposed the shot. - Plan on using external
lighting for your closest shots with the A85.
"Davebox" Test Target
Good overall exposure and color, good dynamic range.
Both the A85's Auto and Manual
white balance settings produced good results here, so I stuck with the
Auto setting for the main selection. (The Daylight
setting resulted in a slight warm cast.) The exposure here is about right,
and the A85 has no trouble distinguishing the subtle tonal variations
of the Q60 target. The large color blocks look pretty good to the eye,
with the slightly boosted saturation that's characteristic of consumer
digicams. The A85 though, is an interesting example of a situation in
which less than perfectly accurate color actually ends up looking very
good to the eye: The analytical results from Imatest show that the cyan
colors are hue-shifted significantly toward the blues, and that some of
the blues are shifted a bit away from purple. Despite these inaccuracies
in absolute color values, I'd say that the A85's color is excellent. (The
hue shifts in cyan and blue colors are likely there to produce more appealing
sky colors.) Detail is strong in the shadow area of the charcoal briquettes,
with high noise.
Good low-light performance, with relatively low image noise. Autofocus works down to a bit darker than one foot-candle. (Slightly darker than typical city street lighting at night.)
The A85 produced clear, bright, usable images down to the 1/16 foot-candle (0.67 lux) limit of my test at the 200 and 400 ISO settings. At ISO 100, images were bright as low as 1/8 foot-candle (1.3 lux), and at ISO 50, images were bright as low as 1/4 foot-candle (2.7 lux). Color was good with the Auto white balance, though just slightly pink at the lower light levels. The A85 handled image noise well here, producing low noise levels at the 50 and 100 ISO settings, and only a moderate level at ISO 200. Even at ISO 400, noise is high, but not overpowering, at least not compared to what I'm accustomed to seeing from consumer digicams at that level. While the A85 could successfully shoot at very low light levels though, its autofocus system worked only down to about 0.7 foot-candles though, just a little darker than typical city night scenes. The table below shows the best exposure I was able to obtain for each of a range of illumination levels. Images in this table (like all sample photos) are untouched, exactly as they came from the camera.
(Note: If you'd like to use a light meter to check light levels for subjects you might be interested in shooting, a light level of one foot-candle corresponds to a normal exposure of two seconds at f/2.8 and ISO 100.)
Flash Range Test
Slight underexposure with the flash, falloff starts at 9-10 feet.
In my testing, the A85's flash illuminated the test target all the way out to 14 feet, though with a significant decrease in intensity. Flash power was fairly consistent to about 10 feet, then fell off in intensity from there. Below is the flash range series, with distances from eight to 14 feet from the target.
High resolution, 1,150 lines of "strong detail." Average barrel distortion, higher than average pincushion though.
The A85 performed pretty well on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 800 lines per picture height, in both horizontal and vertical directions. I found "strong detail" out to at least 1,100 lines vertically, 1,200 lines horizontally. "Extinction" of the target patterns occurred around 1,500 lines.
Using its "MTF 50" criteria, Imatest reported average resolution of 943 line widths/picture height, or 1113 LW/PH when normalized to a standard 1-pixel sharpening.
Optical distortion on the A85 is about average at the wide-angle end,
where I measured an approximate 0.8 percent barrel distortion. The telephoto
end fared only slightly better, as I measured a 0.6 percent pincushion
distortion there. Chromatic aberration is quite low, showing three or
four pixels of very light coloration on either side of the target lines.
(This distortion is visible as a very slight colored fringe around the
objects at the edges of the field of view on the resolution target.) Overall,
a good quality lens.
Resolution Series, 50mm
Resolution Test, Zoom Series
Viewfinder Accuracy/Flash Uniformity
Excellent accuracy from the LCD monitor, but a very tight optical viewfinder.
The A85's optical viewfinder is very tight, showing only about 77 percent frame accuracy at both wide angle and telephoto zoom settings. The LCD monitor proved much more accurate, at about 100 percent. Given that I like LCD monitors to be as close to 100 percent accuracy as possible, the A85's LCD monitor is just about perfect in this respect, but the camera really needs a more accurate optical viewfinder. Flash distribution is somewhat uneven at wide angle, with strong falloff at the corners and edges of the frame. At telephoto, flash distribution is more even, with only slight falloff in the corners.
A85 Test Images
A85 Imatest Results
A85 "Picky Details"
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