Digital Cameras - Canon PowerShot A75 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!|
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 A75 produced good color, but at the cost of higher contrast than I'd prefer.
The shot at right was taken with a +0.3 EV exposure compensation adjustment, as the +0.7 EV adjustment resulted in too bright of an image (al the midtones were perhaps a bit more to what most consumers would prefer). Midtone detail is pretty good, although the contrast is slightly high here, with some lost highlights and dark shadow areas. I chose the Auto white balance setting as the most accurate overall, though it differed only slightly from the Daylight and Manual settings.
Overall color is pretty good, although just a hint reddish. The red cast is most noticeable in Marti's skin tone, which is more ruddy than usual. The blue flowers in the bouquet are a little dark, with a little more purple in them than in real life. (This is a difficult blue for many digicams to contend with, and in reality is a light navy blue, with only a touch of purple in it.) The red flowers are a tad oversaturated, but saturation is about right elsewhere. Resolution is high, and detail is fairly strong in the shadows, with low noise.
To view the entire exposure series from -0.3 to +0.7 EV, see files A75OUTAM1.HTM through A75OUTAP2.HTM on the thumbnail index page.
Slightly contrasty exposure again, but strong detail and high resolution.
Exposure and color balance are similar to the shot above, with slightly high contrast and stronger red tints. The shot at right was taken at the default exposure setting, which produced fairly bright midtones but almost too-bright highlights. The A75 features a 3x optical zoom lens, which helps prevent any strong distortion of Marti's features. Resolution and detail are even stronger in this close-up shot, with better definition in Marti's hair and facial details.
To view the entire exposure series from -0.3 to +0.3 EV, see files A75OUTFACAM1.HTM
through A75OUTFACAP1.HTM on the thumbnail index
Indoor Portrait, Flash:
A bright, powerful flash with good coverage. Warm color balance from the incandescent lighting though.
The A75's built-in flash was a bit dim at the default
exposure setting, requiring a +1.0 EV exposure
compensation adjustment. The camera's flash is fairly strong, resulting
in slighlty harsh lighting on the subject, with dark shadows on the background
wall. The color is a bit warm overall though, thanks in part to an orange
cast from the fairly strong incandescent lighting in the room. Marti's
skin tone is warm and reddish from the color cast, and the blue flowers
of the bouquet are dark and purplish.
Indoor Portrait, No Flash:
Good color with the Incandescent white balance option, and a good exposure as well (though the highlights are slightly hot).
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 A75's Incandescent white balance setting did the best job here, though overall color was a little warm-hued. Still, the whites were the most accurate, and skin tone looked the best to my eye. The Manual setting produced a very good-looking image as well, but with a stronger yellow cast, which some people may in fact prefer, as it preserves more of the mood of the original lighting. (The Auto setting had a really tough time here, and produced a very strong orange cast.) The shot at right was taken with a +1.0 EV exposure compensation adjustment, which just borders on overdoing the highlights on the white shirt. Despite the pink cast, overall color looks good (though the blue flowers are dark and purplish).
Given that it has only a 3-megapixel CCD, I'm surprised to see as much noise as I do in the A75's images, but most folks really aren't likely to notice it at ISOs of 50 and 100 indoors and as high as 200 outdoors. Under the very warm-toned incandescent lighting of this shot though, image noise becomes quite apparent at ISO 200, and objectionable at ISO 400. - Plan on ISO 200 as a practical upper limit for indoor shots, and keep the ISO at 100 or below for the best results.
Great color and resolution, with well-defined detail.
On this shot, the A75's Auto and Daylight
white balance settings produced nearly identical results, with slightly
warm color overall. Though just a hint on the cool side, the A75's Manual
white balance produced the most accurate white value on the house trim.
Resolution is high, and detail is strong in the front shrubbery, as well
as in the tree limbs above the roof. Details are also sharp throughout
the center of the frame, with only faint corner softness in the top left
High resolution with clear detail, but the slight overexposure 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. The A75 performs well, capturing a lot of fine detail in the tree limbs over the roof, as well as in the fine foliage in front of the house. Leaf patterns in the front shrubbery are pretty well defined, as are the linear details on the house front. Details are also reasonably sharp, from corner to corner. The camera loses all but the strongest details in the bright white paint surrounding the bay window, a trouble spot for many digicams, but detail is stronger in the shadow area above the front door, however. Exposure is a bit on the bright side, but color looks good. Here's a shot with the camera's Postcard setting, at the 1,600 x 1,200-pixel resolution. 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 A75's lens is equivalent to a 35-105mm zoom on a 35mm camera. That corresponds to a standard wide angle to a moderate telephoto. Following are the results at each zoom setting.
Good color with the Manual white balance (though slightly cool), and high resolution.
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. The A75's Manual white
balance setting handled the challenge well, despite a slight cool cast.
Both the Auto and Daylight
settings resulted in warmer color balances. The blue robe looks pretty
good, though with faint purplish tints in the deeper shadows. Skin tones
are slightly pale, but still appear more natural than in the other shots.
Resolution is high, judging from the detail in the embroidery of the blue
robe, as well as in the definition of the beaded necklaces and flower
A nice small macro area with good detail. Color balance is pinkish and warm though, and the flash has trouble up close as well.
The A75 performed about average in the macro category, capturing a minimum
area of 2.59 x 1.95 inches (66 x 49 millimeters). Resolution is high,
with good detail in the coins, dollar bill, and brooch. The A75's flash
has trouble throttling down for the macro area, and overexposes the shot.
(Plan on using external lighting for your closest macro shots.)
"Davebox" Test Target
Accurate, well-saturated color, slight oversaturation on bright reds and blues.
Both the A75's Auto and Daylight
white balance settings produced similar, slightly warm images, but the
Manual setting produced a nearly accurate color
balance. I boosted the default exposure by +0.3 EV here, to get the white
block on the MacBeth target to where I felt it should be, but that left
the overall image a tad bright. Colors are very accurate in the large
color blocks, but the slightly bright exposure left some of them a little
undersaturated. Even with the overexposure though, the large red and blue
primary color blocks are just a little oversaturated. Detail is moderate
in the shadow area of the charcoal briquettes, with low noise.
Good low-light performance, with good color even at the darkest light levels. An autofocus illuminator lets the camera focus in complete darkness, but only on nearby objects.
The A75 produced clear, bright, usable images down to the 1/16 foot-candle (0.67 lux) limit of my test, at the 100, 200, and 400 ISO settings. At ISO 50, images were bright as low as 1/8 foot-candle (1.3 lux), though you could still see a fair amount of detail even at the 1/16 foot-candle light level. The A75's autofocus illuminator lets it focus even in complete darkness, but its range is limited to a few feet when there's no other light available. In less than complete darkness, the camera's focusing range is proportionately higher. Color was good and accurate throughout the series as well. Image noise was low throughout the ISO 50 and 100 series, and only moderate at ISO 200. However, at ISO 400, image noise was quite high. A very good performance overall though, particularly for an entry-level camera. 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 on this site) 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
Pretty good flash intensity at close range, but increasing falloff with each additional foot of distance.
In my testing, the A75's flash illuminated the test target all the way out to 14 feet, but showed a significant decrease in intensity at distances greater than 8-9 feet or so. (This is consistent with Canon's own rating of the A75's flash, which pegs its range as 14 feet at wide angle and 8 feet at telephoto.) Below is the flash range series, with distances from eight to 14 feet from the target.
High resolution, ~1,000 lines of "strong detail." Average barrel distortion at wide angle, and a slight amount at telephoto.
The A75 turned in about an average on the "laboratory" resolution test chart for its 3-megapixel class, actually not doing quite as well as last year's A70 model. It started showing artifacts in the test patterns at resolutions as low as 600 lines per picture height, in both horizontal and vertical directions, and they became quite strong by the 1,000 line point. While there was some detail present out to 1,100 lines (the rating I gave the A70 last year), I felt that I could only justify a rating of 1,000 lines, given the artifacts beyond that level. "Extinction" of the target patterns occurred around 1,300 lines.
Optical distortion on the A75 is slightly better than average at the wide-angle end, where I measured approximately 0.7 percent barrel distortion. The telephoto end fared quite a bit better, as I measured 0.2 percent barrel distortion there. Chromatic aberration is pretty good, as there was only fairly faint coloration surrounding the target lines in the corners. (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.) The image was also reasonably sharp across the frame, with only slight softness in some of the corners, not extending very far into the image.
Resolution Series, Wide Angle
Resolution Test, Telephoto
Viewfinder Accuracy/Flash Uniformity
Excellent accuracy from the LCD monitor, but a very tight optical viewfinder.
The A75's optical viewfinder is very tight, showing only about 75 percent frame accuracy at wide angle, and about 77 percent at telephoto. The LCD monitor proved much more accurate, showing about 99+ percent accuracy at both lens settings. Given that I like LCD monitors to be as close to 100 percent accuracy as possible, the A75's LCD monitor is essentially perfect in that regard, but the optical viewfinder could really use some help. Flash distribution is bright and fairly even at wide angle, with just a little falloff at the corners and edges of the frame. At telephoto, flash distribution is dimmer but more uniform.
A75 Test Images
A75 "Picky Details"
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