Digital Cameras - Canon Powershot A520 Test Images
|I've begun including links in our reviews to a Thumbnail index page for the test shots. The data on this page includes a host of information on the images, including shutter speed, ISO setting, compression setting, etc. Rather than clutter the page below with all that detail, we're posting the thumbnail index so only those interested in the information need wade through it!|
The extreme tonal range of this image makes it a tough shot for many digital cameras, 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 A520 performed well here.
The shot at right was taken with a +1.0 EV exposure compensation adjustment, which resulted in high contrast, but reasonably bright midtones. The highlights on the white shirt and in the flower bouquet are quite bright, as a result of the high contrast, and the shadows are fairly dark. All three of the A520's white balance settings produced good results here, though I chose the Auto setting as the most accurate overall. The Daylight setting had a very slight warm cast, and the Manual setting had a reddish tint. Still, good results with each.
Marti's skin tones look good, if slightly pink, but the blue flowers in the bouquet are a hint dark, with purplish tints. (Many digital cameras have trouble with this blue, which is actually a pure, light navy.) Color looks good throughout the rest of the frame, with good saturation as well. Resolution is very high, and detail is strong in Marti's features as well as in the flower bouquet. Details are also quite sharp. Shadow detail is moderate, and image noise is low.
To view the entire exposure series from zero to +1.0 EV, see files A52OUTAP0.HTM
through A52OUTAP3.HTM on the thumbnail index page.
Excellent resolution and detail, but again, high contrast.
Though contrast is again high from the high-key lighting, midtone detail is good here. The shot at right was taken with a +0.3 EV exposure compensation adjustment, which is a little bright, especially in the highlights. The A520's 4x zoom lens helps prevent strong geometric distortion in Marti's features, and captures sharp details. Resolution and detail are even better in this close-up shot, with excellent definition in Marti's face and hair.
To view the entire exposure series from zero to +1.0 EV, see files A52OUTFACAP0.HTM
through A52OUTFACAP3.HTM on the thumbnail
Indoor Portrait, Flash:
Good performance from the camera's flash, with fairly good color as well.
The A520's built-in flash illuminated the subject fairly well with a +1.0 EV exposure compensation adjustment, though the default exposure was dim. Overall color is warm from the background incandescent lighting, with orange tints on Marti's hair and shirt, as well as on the background. Marti's skin tone looks pretty good, though a little warm, and the blue flowers are dark and purplish.
To view the entire exposure series from zero to +1.0 EV, see files A52INFP0.HTM
through A52INFP3.HTM on the thumbnail
Indoor Portrait, No Flash:
Good color with the Incandescent white balance, and good exposure as well.
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. The A520's Auto white balance setting fell victim to this trap, and produced a strong orange cast. However, the A520's Manual and Incandescent settings both produced nearly accurate color, though I settled on the Incandescent setting for the main shot. (The Manual setting was a touch greenish.) Marti's skin tone looks good, though slightly pinkish, but the flower bouquet looks nearly accurate. The blue flowers do have slight purplish tints to them, but their color is just about right, considering the difficult light source here. The main shot was taken with a +1.0 EV exposure compensation adjustment, which is about average.
To view the entire exposure series from zero to +1.3 EV, see files A52INTP0.HTM through A52INTP4.HTM on the thumbnail index page.
Accurate color, with high resolution and strong detail.
While all three of the A520's white balance settings tested performed
pretty well here, I chose the Manual
setting as the most accurate overall, based on the white value of the
house trim. The Daylight
settings resulted in very slight warm casts, but results were still quite
good. Resolution is very high, and detail is strong in the tree limbs,
front shrubbery, and house front. Details are also sharp throughout the
High resolution and strong detail, but high contrast limits the dynamic range slightly.
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 A520 captures a lot of fine detail. The leaf patterns in the front shrubbery and in the tree limbs above the roof show a lot of fine detail, as does the brick pattern on the house front. Details are sharp and well-defined, though the corners of the frame are slightly soft. The bright sunlight causes the camera to lose some detail in the bright white paint surrounding the bay window, which is a trouble spot for many digital cameras. Detail is moderate in the shadow area above the front door as well, further evidence of a limited dynamic range. The table below shows a standard resolution and quality series, followed by ISO and color effects series.
Color Effects Series:
Lens Zoom Range
A very good 4x 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 (4x, in this case), and at full telephoto with the digital zoom enabled. The A520's lens is equivalent to a 35-140mm zoom on a 35mm camera. That corresponds to a moderate wide angle to a pretty substantial telephoto. Following are the results at each zoom setting.
Slightly cool color, though good overall results. Very high resolution and strong detail.
This shot is often a tough test for digital cameras, as the abundance
of blue in the composition frequently tricks white balance systems into
producing a warm color balance. Though slightly cool, I chose the A520's
white balance setting for the main shot here, despite slightly pale and
magenta skin tones. Both the Auto
settings resulted in warmer color casts. The shadows of the blue robe
are somewhat purplish from the magenta tint, and the blue background has
some purplish tints as well. Resolution is very high, and the embroidered
bird wings on the blue robe show a lot of detail, as well as the models'
accessories and instruments. (The original data file for this poster was
only 20MB though, so cameras like the A520 are capable of showing more
detail than the poster has in it.)
A small macro area with great detail. Flash has trouble up close though.
The A520 performed very well in the macro category, capturing a minimum
area of 2.03 x 1.52 inches (51 x 39 millimeters). Resolution is high and
detail is strong throughout the frame, though the coins and brooch are
soft due to the close shooting range. Details soften slightly toward the
furthest corners of the frame, but are sharp on the dollar bill. (Most
digital cameras produce images with soft corners when shooting in their
Macro modes.) The A520's flash
had trouble at such close range, and overexposed the majority of the image,
leaving a strong shadow in the lower right corner of the frame.
"Davebox" Test Target
Nearly accurate color, and a good exposure.
The A520's Manual
white balance setting produced the best results here, as the Auto
settings were both slightly warm. Exposure looks about right, and the
A520 had no trouble distinguishing the subtle tonal variations of the
Q60 target. The large color blocks are all slightly cool, but still look
pretty good. The shadow area of the charcoal briquettes shows good detail,
with moderately low noise.
Color Effects Series:
Excellent low-light performance. Good color and exposure, with low image noise, at the lowest light levels of this test.
The A520 produced clear, bright, usable images down to the 1/16 foot-candle (0.67 lux) limit of my test, with good color at the 100, 200, and 400 ISO settings. At ISO 50, images were bright down to the 1/8 foot-candle (1.3 lux) light level, though the target is visible at the lowest light level of the test. Noise is fairly low in most shots, though it increases with the higher intensity settings. At ISO 400, noise is quite high, but the pixels aren't so bright that they ruin the image. Since city street-lighting at night generally corresponds to a light level of about one foot-candle, the A520 should perform well in most average night settings. 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
A weak flash, with very low intensity even at eight feet.
In my testing, the A520's flash only barely illuminated the test target at 14 feet, showing significant decreases in intensity from the nine-foot distance on. Below is the flash range series, with distances from eight to 14 feet from the target.
High resolution, 1,200 lines of "strong detail." High barrel distortion at wide angle.
The A520 performed well on the "laboratory" resolution test chart for its 4.0-megapixel class. It started showing artifacts in the test patterns at resolutions as low as 1,000 lines per picture height vertically and horizontally. I found "strong detail" out to at least 1,200 lines. "Extinction" of the target patterns didn't occur until about 1,500 lines. Here's a sample image with the camera's Low Sharpness setting.
Geometric distortion on the A520 is about average at the wide-angle end,
where I measured approximately 0.9 percent barrel distortion. The telephoto
end fared quite a bit better, as I measured approximately 0.05 percent
barrel distortion (about one pixel). Chromatic aberration is virtually
nonexistent, as I couldn't really find any strong pixels of coloration.
(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.)
Resolution Series, medium focal length
Resolution Test, Zoom Series
Viewfinder Accuracy/Flash Uniformity
A tight optical viewfinder, but nearly accurate LCD monitor.
The A520's optical viewfinder is very tight, showing only 81 percent of the final image area at wide angle and telephoto zoom settings. The LCD monitor actually proved very slightly loose, showing just a bit more than what made it into the final frame, though results were near 100 percent accuracy. Given that I like LCD monitors to be as close to 100 percent accuracy as possible, the A520's LCD monitor performed pretty well here, but its optical viewfinder could use some help. Flash distribution is a little uneven at wide angle, with some falloff at the corners and edges of the frame. At telephoto, flash distribution is more uniform.
A520 Test Images
A520 "Picky Details"
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