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Minolta Dimage 7

Minolta unleashes the first 5-megapixel camera, with a tack-sharp 7x zoom lens, and amazingly sensitive electronic viewfinder!

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Page 12:Test Results & Conclusion

Review First Posted: 5/23/2001

Test Results
Given that the Dimage 7 breaks so much new ground in its resolution and lens quality, we're going to depart from our usual format here a little, and spend a bit more time elaborating on the results of our tests. - Our normal approach would be to simply refer our readers to the Dimage 7's Picture Analysis Page, and encourage them to form their own opinions. We still encourage that practice, as it's our firm belief that your eyes need to be the final judge of which camera is right for you. What we'll do here though, is to show cropped samples from some of our test shots to illustrate particular points we view as important. We'll also show small version of some of the shots, so you can quickly form an opinion of color, night-shooting capability, etc.

Of course, the big story with the Dimage 7 is its resolution. With a 5.2 megapixel CCD, it has dramatically more pixels than the by-now-standard 3.3 megapixel cameras and even trumps 4 megapixel designs by a good 25%.

The illustration above shows samples cropped from our laboratory resolution-target shots, taken with three high-end digicams: The 5-megapixel Dimage 7, the 4-megapixel Olympus E-10, and the 3.3-megapixel Nikon Coolpix 995. Our normal practice is to apply no adjustment to any of the camera images we shoot, but in this case, we've tone-adjusted the shots from the various cameras, so they'd match in brightness, contrast, and color cast. - This was important, as differences in contrast can significantly affect perceived resolution, and this close juxtaposition would have exaggerated the effect of any differences.

In the figure, we've marked three points on each curve, which serve to characterize the cameras' resolving power. The red arrow indicates the point at which the first (often barely detectable) artifacts appear in the target image: This is the "visual" resolution, as defined by the ISO-12233 standards definition for digital camera resolution, and is the point that we normally use as the resolution number in reporting our test results. Note though, that the artifacts are often very subtle, consisting mainly of slight, anomalous thickening or blurring of the lines. This is one of the unfortunate aspects of the ISO-12233 standard, in that there's often a great deal of visible detail present well beyond the spatial frequency at which the first artifacts appear, and this number therefore sometimes underreports the resolution relative to what most users would feel was an acceptable level of artifacts or blurring.

Because the ISO standard is so conservative, we often report in our reviews that we saw "strong detail" out to such and such a point. Our criteria for "strong detail" has no formal definition, and is quite subjective, but does indicate resolution of a sort that may be considered useful by our readers. - This also seems to correlate a bit better with observations on "natural" objects in our other test images. Our criteria for "strong detail" is that the target lines still be clearly visible, although some blurring or aliasing may be present.

The final point we've marked is the "extinction" point, at which the camera completely loses all ability to distinguish the target lines from one another, and the image blurs into a more or less uniform grayness. This parameter really has no formal definition whatever, and is of questionable value in determining "real life" camera performance. It does correlate somewhat with the "sharpness" of a camera's images (as distinct from "resolution"), and some authors regularly discuss it. While it does seem to provide some indication of image sharpness, the relationship is not well established, and "extinction" numbers can be misleading.

In the illustration here though, all three indicators seem to line up fairly well, with the "Strong Detail" parameter in particular showing clear differences between the 3, 4, and 5 megapixel devices. The 5 megapixel Dimage 7 shows significantly greater resolution than even the 4 megapixel E-10, and relative to the 3.3 megapixel camera, the difference is dramatic.

Detail example, vs Nikon Coolpix 995
(a top-performing 3.3 megapixel camera)

995, original size

995, resized in Photoshop
(Bicubic Interpolation)

Dimage 7, straight from camera

These shots show how the laboratory tests translate into the real world: The Dimage 7's shots are again compared to those of the Coolpix 995, a very good 3.3 megapixel camera. The difference between 3.3 and 5.2 megapixels is very evident.

Corner sharpness examples. (Vs anonymous 3.3 MP camera)

Corner detail from "mystery" camera.

Matching corner detail from Dimage 7

One of the things that most impressed us with the Dimage 7 was the obvious quality of its lens: It shows better corner sharpness than the lenses of most digicams we've tested, and much lower chromatic aberration as well. The shots above are cropped from outdoor shots taken by the Dimage 7 and 3.3 megapixel model. (No, not the 995 again: We didn't feel it would be fair to single out a specific competing model in this example, since corner softness and chromatic aberration are so widespread among the prosumer cameras we've seen.) The improved sharpness of the Dimage 7's lens is obvious (there's more difference in sharpness here than would be accounted for merely by the difference in resolution), as is the lower level of chromatic aberration, as evidenced by the almost complete lack of red/green fringes around the dark tree branches.

Color saturation variations.
Color saturation variations. Middle is nominal, top left minimum, bottom right maximum.
(On the prototype camera, maximum color saturation setting darkened image somewhat. - We're guessing that this is just a prototype glitch...)

The Dimage 7's color accuracy was quite good for a prototype unit, and we really liked the fine gradations available via the Digital Effects control. The combination of fine step sizes with a total of 7 variations mean that you can really configure the camera to match your own particular color preferences. (For instance, when shooting photos with it for personal use, we routinely ran the color saturation up by one or two notches on the Digital Effects control.) The steps sizes on most cameras offering saturation adjustments are too large to be considered for use as a routine tweak on camera operation, but rather as special effects to be trotted out on those occasions calling for something fairly dramatic. The thumbnails above show the result of the full range of saturation adjustments being applied to the Davebox image.

Dimage 7 Samples in normal lighting conditions.

Before we get into the low light images, the thumbnails above show some of our standard test images, for those interested. (Once again, be merciful with our bandwidth, these are all about 2 megabytes in size.)

Examples shot under household incandescent lighting. (Lower light, so somewhat more noise.)

Auto White Balance

Incandescent White Balance

Custom White Balance

The Dimage 7's white balance system did a great job too: It's automatic setting handled most normal lighting situations quite well, although we found the custom option provided more accurate neutral tones in most situations. Our Indoor Portrait shot is a particularly tough test for many cameras' white balance settings, as the household incandescent lighting it's shot under has a very strong yellow cast. The three thumbnails above show the effect of the Dimage 7's Auto, Incandescent, and Manual white balance settings. We particularly liked the behavior of the Incandescent setting in this instance, feeling that it left just enough of the yellow cast in the image to capture the mood of the lighting, while still providing a well-balanced photograph. The Dimage 7 performed exceptionally well in the low-light category, as we obtained very bright, useable images at light levels as low as 1/16 foot-candle (0.67 lux) at all four ISO settings (100, 200, 400, and 800). We noticed a slight magenta cast from the low light level, but all four ISO settings produced good color overall. The 800 ISO setting produced the brightest image, though with a very slight, milky haze. Noise remained moderately low at the 100 and 200 ISO settings, increasing to a moderate level at 400 ISO and to a high level at 800 ISO. (We direct readers to Mike Chaney's excellent Qimage Pro program, for a tool with an amazing ability to remove image noise without significantly affecting detail.) To put the Dimage 7's low-light performance into perspective, an average city night scene under modern street lighting corresponds to a light level of about one foot-candle, so the camera should easily handle much darker situations without the flash.

NOTE: These images were shot in *low* light. Daylight shots show much lower noise.

In addition to our studio tests, we took the Dimage 7 out for an excursion to the local mall late one night, with results shown above. (Click on each image to see the full-sized version, but beware, they run about 2 megabytes apiece.) The quality of these night shots is simply outstanding: There's very little noise (particularly impressive, given the sensor's resolution, as well as the prototype status of the camera we were shooting with), and even more dramatically, there's no sign of the dreaded "purple fringe" problem seen in so many digicams in similar situations. (This phenomena has commonly been referred to as chromatic aberration, but we don't think it's actually that, since it seems to be much more a function of light overload than simple light/dark contrast breaks.) On the throwaway shot of the Best Buys store, we felt the lack of bleeding around the grossly overexposed streetlights was a significant point. The fourth shot above is of a house across the street, in a rather dark residential neighborhood. This was shot at ISO 800, with a 4 second shutter speed, and is *considerably* brighter in this image than it appeared to the naked eye: The fairly bright sky behind the house was in fact only dimly visible as city glow reflecting from low overcast. (Note that the noise level on this shot may be lower than you'd see normally: We shot this photo at the smaller 1600x1200 image size, so there may be some averaging between adjacent pixels going on, which would tend to reduce the noise level somewhat.) Bottom line, the Dimage 7 looks like it will be an incredible low-light performer.

Oh - and lest we forget to underscore this point again: The Dimage 7's electronic viewfinder worked perfectly well for framing all of these night shots! (The house shot was so dim that the EVF view was extremely noisy, but the fast was that we could still use the EVF to frame the image.) If you've ever been frustrated by the inability of an EVF to function in low lighting, you have to check out the one on the Dimage 7: It's the first EVF we've seen that we felt really could substitute for a true optical viewfinder.

Viewfinder Accuracy & Flash Uniformity, Wide Angle

Viewfinder Accuracy & Flash Uniformity, Telephoto

Speaking of the viewfinder, the one on the The Dimage 7 is very accurate, which showing approximately 99.4 percent of the final image area with the lens at full wide angle. At the telephoto setting, it's just a little loose, showing very slightly more in the frame than what ends up in the final image area. Really, it's about as close to a 100% view as possible though, so we give the camera high marks for viewfinder accuracy. Also as measured in our viewfinder accuracy test, flash distribution is fairly even at the telephoto setting, though very dim, with a slight reflection present at the center of the target. We also noticed a bright, vertical line just right of center. At the wide angle setting, flash distribution is fairly even and bright, with just a little falloff at the corners of the target.

The Dimage 7 performed very well in the macro category, capturing a fairly small minimum area of just 1.92 x 1.44 inches (48.76 x 36.57 millimeters), which is among the best we've seen. Detail and resolution are excellent, with very sharp details throughout the image. The printing on the dollar bill is very clear, as are the tiniest details of the coins. Color balance is a little warm, giving the gray background a reddish tint. The Dimage 7's built-in flash has a lot of trouble throttling down for this very tiny macro area, completely overexposing the image and washing out the color and details.

Throughout our testing, we were very pleased with the Dimage 7's performance. Resolution and detail are the highest of any camera we've tested to date, in over three years of testing. (May, 2001) The lens is very sharp, with very little chromatic aberration, and great corner sharpness. Exposure control is excellent, with great control over color, contrast, and sharpness. Macro and low-light performance are both excellent, leading us to think that the Dimage 7 is a good camera for just about any shooting situation. At an introductory price of $1,500, it clearly isn't a camera for the idle snapshooter, but if you're serious about your photography, the Dimage 7 should be at the top of your list for consideration. Very highly recommended.

UPDATE: 8/23/2001
Since this review was first written, we've gotten a production model to test, "lived" with the camera on our Alaska trip, and also seen some other new cameras that challenge the Dimage 7 pretty strongly. Here's where we end up, now that a few more months have gone by:

  1. We're still very impressed with the Dimage 7 - We still think it's a breakthrough product in a number of areas, including its lens (one of the best digicam lenses we've seen period, let alone a long-ratio zoom model) and the fine-grained control it gives you over color, exposure, and contrast. After using it in the field, we have even more appreciation for its control layout too, which is very functional, fast, and easy to get familiar with.

  2. It's no longer the holder of "highest resolution" honors, as newer cameras have equaled or surpassed it.

  3. Despite the fine-grained contrast and saturation control, we'd like to see improvements in the camera's basic exposure system. In high dynamic-range scenes (ranging from very light to very dark), it tends to overexpose the highlights somewhat, and we found it hard to correct for this without producing overly-dark images. Likewise, while we can get photos that we consider to be very pleasing by boosting the saturation two notches, we'd like to see the default color somewhat brighter.

  4. We're less carried away with the ferroelectric EVF than we were initially, although we still think it's the best EVF we've seen to date. Specific enhancements we'd like to see are more pixels (to provide better spatial resolution and avoid some of the "crackled" effect on scenes with fine detail), a better set of eyepiece optics, and less tendency to lose highlight detail.

Overall, the Dimage 7 is a very impressive picture-taking tool, with a tremendous range of control and a genuinely great lens system. It does seem to be a camera that polarizes people a great deal, as witness some of the wildly divergent opinions and reactions in our discussion forums. (Click the link at the bottom of this page to go directly to the discussion thread associated with this review.) For this reason, we'd strongly advise prospective purchasers to one way or another get their hands on a unit in a camera shop to see how the EVF and general "feel" of the camera strike you. If this means fewer sales through our advertisers, so be it: Our ultimate mission is to lead people to camera purchases that they're happy with, and in the case of this camera, it seems that holding one in your hands is an important part of that process.

While some of our rabid initial enthusiasm for the Dimage 7 mitigated a bit once we'd spent some time with a production unit, we're still very positive on the camera overall. - And judging from what we're hearing from many readers and the dealer channel, it seems we're not alone in that opinion: At least as of this writing in late August 2001, Dimage 7s are figuratively flying off dealer shelves. Minolta really broke out of the pack in early 2001 with the Dimage 7, being the first manufacturer to jump into the 5 megapixel arena. As noted though, the story of the Dimage 7 isn't just (or even primarily) one of resolution: The 7x zoom lens is one of the best we've seen on a non-removable-lens digicam, with excellent sharpness corner to corner, and very little chromatic aberration. The zoom lens also covers a very useful range of focal lengths, extending from an equivalent of 28mm at the wide angle end to 200mm at the telephoto end -- with the 28mm offering substantially more coverage than the standard 35mm focal length. While it appears to be at least somewhat a matter of personal preference and opinion, we feel that the Dimage 7's electronic viewfinder is superior to conventional LCD designs: This is the first EVF we've seen that is actually usable in reasonably dim shooting conditions. The ability to fine-tune color saturation and contrast allows users to adjust the camera to suit their own specific preferences. Add a capable (if proprietary) hot shoe flash connector, front-element filter threads, CF Type II (and Microdrive) compatibility, and topnotch ergonomics and interface design, and you have a very exciting camera. We liked the Dimage 7 a great deal, and it seems to be making a lot of owners happy too. If you're looking for a prosumer camera with high resolution, no-excuses optics, and great picture-taking control, the Dimage 7 could be the camera you've been waiting for.

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