Digital Cameras - Minolta Dimage X Test Images
(Original test posting: 03/20/02)
|For those interested in exposure and file size information, I now include links in my reviews to a Thumber-generated index page for my test shots. The Thumber data includes a range of information on the images, including shutter speed, ISO setting, compression setting, etc. Rather than clutter the page below with *all* that detail, I'm posting the Thumber 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 digicams, which is precisely why I set it up this way. The object is to hold highlight and shadow detail without producing a "flat" picture with muddy colors, and the Dimage X performed well. The shot at right has a +0.3 EV exposure compensation adjustment, which maintained highlight detail while brightening the midtones just a little. Increasing the exposure compensation to +0.7 EV produced better midtones, but at the cost of highlight detail, so overall I felt the 0.3EV shot was the best.
I really like the color in this image (and in most of the Dimage X's shots): The skin tones look very good, even though they're just a tad pink, they're very pleasing, at least to my eyes. The blue flowers are a little dark, and have just the slightest hints of purple in them, but overall their color is much better than that managed by most digicams on this shot. Resolution is pretty good, not quite a crisp as the best 2 megapixel digicams I've seen, but not bad either. Shadow detail is excellent too, with only a moderate noise level. Overall, a really excellent performance!
Results in this shot are similar to the one above, and the 3x lens helps prevent any distortion of the model's features. (If you intend to shoot close portraits of people, you really need a zoom lens to avoid the distortion wide-angle lenses cause in people's features.) The image at right again has a +0.3 EV exposure adjustment, which brightens the midtones but loses some detail in the highlight areas. Resolution is higher in this shot, with stronger detail in the model's face and hair, although there's a slight lack of crispness in the model's hair. Shadow detail is again very good, with pretty low noise.
|Indoor Portrait, Flash:
Good intensity, but picks up a fair bit of color from the strong incandescent room lighting.
The Dimage X's flash illuminates the subject well, without losing any highlight details. Brightness-wise, it also achieves a good balance between the room lighting and the strobe. The only problem is that the relatively bright household incandescent lighting produces an orange cast. Despite this, the colors in the flowers are surprisingly accurate and well saturated. I'd like to see less color from the room lighting, but I'll gladly accept some of that to achieve the good balance between room and flash lighting seen here. A pretty good job overall.
Portrait, No Flash:
Strong color casts with both white balance settings. - Needs some work on incandescent white balance.
This shot is always a tough test of a camera's white balance capability, given the strong, yellowish color cast of the household incandescent bulbs used for the lighting, and the Dimage X had quite a bit of trouble with it. The Incandescent white balance setting resulted in a greenish-brown image, while the Auto setting produced a strong red color cast. Neither image has what I would call "accurate" color, but I chose the Incandescent setting for the main image, simply because it's easier to look at. A color adjustment in an image editing application may do the trick and produce a more natural-looking image. The main image has a +0.3 EV exposure adjustment, which looks about right.
Good resolution and color, though details are a little soft.
The Auto white balance setting produced the most accurate color here, while the Daylight setting resulted in a greenish color cast. Color looks good with the Auto white balance setting, though just a touch yellow. Resolution is fairly high (that is, there's a lot of detail there), but the details themselves are a bit soft. The corners are also slightly more soft than the rest of the image, a common issue with consumer digcams, and particularly subcompact models. On the Dimage X, corner softness is fairly minor at medium and telephoto focal lengths, becoming more pronounced at wide angle.
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 Dimage X captures a lot of fine detail throughout the frame, though details are again slightly soft. All four corners of the frame are again slightly soft, but it doesn't extend too far into the picture. The fine foliage details in front of the house and in the tree limbs show fairly good definition. The bright sunlight causes the Dimage X to lose most of the detail in the white bay window area, revealing a somewhat limited dynamic range. The shadow area above the front door fares only a little better, showing most but not all of the brick pattern. The table below shows our standard resolution and quality series.
|Lens Zoom Range
A typical 3x zoom range.
After a number of requests from readers to show the full range of each camera's zoom lens, I now routinely include the following series of shots, showing the field of view with the lens at full wide angle, at 3x telephoto, and at 3x telephoto with the 2x digital zoom enabled. The Dimage X's lens is equivalent to a 37-111mm zoom on a 35mm film camera. This is a fairly typical zoom lens range for consumer digicams, just slightly more telephoto than most. Following are the results at each zoom setting.
Great color, resolution, and detail.
In this test, the Daylight white balance produced the most natural color balance, as is typically the case. The Auto setting resulted in a warmer color balance, with very warm skin tones, most likely in response to the large amount of blue in the composition. The Oriental model's blue robe looks about right, with only faint purple tints in the deep shadows. (This is a tough blue for many digicams to get right.) Resolution is pretty good, judging by the embroidery details of the blue robe, and in the beaded necklaces.
Good macro performance, flash throttles down very well, covers evenly.
The Dimage X performed well in the macro category, capturing a minimum area of 3.43 x 2.57 inches (87.1 x 65.3 millimeters). Resolution is high, with great detail in the coins and brooch, as well as in the print on the dollar bill. Color balance is good also. The telephoto lens position results in some slight pincushion distortion, but isn't too bad overall. (And is much better IMHO than the strong barrel distortion I usually see in digicam macro shots.) The camera's flash throttled down very well for the macro area, though intensity was a little dim.
|"Davebox" Test Target
Good color and exposure, a very good performance.
As is often the case with this shot, the Auto white balance setting produced the most accurate color. Daylight white balance resulted in a slightly warm color cast. The large color blocks are fairly accurate, though saturation is a little weak on the yellow one. Exposure is about right, however, as the Dimage X picks up the subtle tonal distributions of the Q60 chart. Detail is strong in both highlights and shadows, with low noise.
Good enough for average city street lighting at night, but no darker.
With a maximum shutter speed of two seconds and with no variable ISO capability, the Dimage X's low-light shooting capabilities are limited to average city street lighting at night (equivalent to one foot-candle or 11 lux). (Although as we see in the flash range test shots below, enabling the flash does seem to double the camera's light sensitivity to ISO 200.) The camera captured bright, clear images at the one foot-candle light level, and a dim image at one-half of a foot-candle. Color balance is pretty accurate at one foot-candle, but gets warmer as the light level decreases further. The table below shows the best exposure obtained for each of a range of illumination levels. Images in this table (like all of our sample photos) are untouched, exactly as they came from the camera.
|Flash Range Test
Good intensity as far as 14 feet.
The Dimage X's flash remained effective as far as 14 feet from the test target. Intensity was brightest at the eight foot distance, but decreased only very slightly as I backed away from the target. Still, intensity remained fairly bright and usable at 14 feet. Oddly, while there didn't seem to be any variable ISO option for normal shooting (see the low light series above), enabling the flash boosted the camera's ISO to 200. Below is our flash range series, with distances from eight to 14 feet from the target.
(WG-18) Resolution Test
A pretty good job, with strong detail to 750-800 lines/picture height.
The Dimage X performed about average for its two-megapixel class on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 600 lines per picture height vertically and horizontally. I found "strong detail" out to about 800 lines vertically, and about 750 lines horizontally. "Extinction" of the target patterns occurred at about 1,000 lines.
Optical distortion on the Dimage X ranges from average to higher than average: I measured an approximate 0.84 percent barrel distortion at the wide-angle lens setting. The telephoto setting fared only a little better, with an approximate 0.50 percent pincushion distortion. The barrel distortion is about average among cameras I've tested (unfortunately, the vast majority of consumer digicams produce more barrel distortion at wide angle than I really consider acceptable), but the pincushion distortion at telephoto is higher than average. Chromatic aberration is fairly broad in its effect, but the coloration is relatively faint. (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 most noticeable distortion on the Dimage X is corner softness in wide-angle shots, although it doesn't extend too far into the frame, and largely goes away at medium and telephoto focal lengths.
(The first production model of the Dimage X had a poorly seated CCD chip, resulting in poor focus on the left side of the frame, and very pronounced corner softness. I've now reshot most of the test images with a second production unit without that problem, with greatly improved results.)
Resolution Series, Wide Angle
Viewfinder Accuracy/Flash Uniformity
A tight optical viewfinder also reveals a shifted/rotated CCD, though LCD accuracy is excellent.
The Dimage X's optical viewfinder was quite tight, showing only about 74 percent of the final frame at wide angle, and approximately 73 percent frame accuracy at telephoto. Both images showed a marked slant toward the lower left corner of the frame, indicating that the Dimage X's CCD is rotated slightly inside the camera. There was also a lot of extra space on the left and bottom sides of the frame in both shots. The LCD monitor produced much more accurate results, showing approximately 98 percent frame accuracy at wide angle, and about 99 percent at telephoto. Since I normally prefer to see LCD monitors as close to 100 percent accuracy as possible, the Dimage X did a great job in this respect. While the LCD viewfinder was very accurate, I'd really like to see much better accuracy from the optical viewfinder. Flash distribution at wide angle shows some falloff in the corners of the frame, as well as along the sides. Distribution at telephoto is much more even.
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