Overall Image Quality
Overall he DiMAGE 7 delivers high resolution, detailed images. The resolution charts (discussed later in this review) show that the combination of lens and 5mp sensor delivers approximately the same levels of resolution as the Sony DSC-S85, the only other greater-than 3 megapixel consumer camera we've reviewed.
If you go to the trouble of running the DiMAGE 7's images through the supplied Minolta Image Viewer (and it is worth the trouble) you're going to get far better colour reproduction. Not understanding the fact that the DiMAGE shoots in its own colour space could well lead new users to dismiss it's colour as dull. This is far from the truth, once converted into the correct colour space it delivers some of the best, most vivid (yet 'believable') colour I've seen of any consumer level digital camera. Indeed it's delivering a wider gamut than we can appreciate through sRGB, more professional or advanced users may well choose to work in one of the other more industry standard colour spaces such as Adobe RGB.
Equally impressive is that big 7x optical zoom with relatively good maximum apertures (F2.8 - F3.5), considering its reach and very chromatic aberrations or image distortion (see below).
Purple Fringing (Chromatic Aberrations)
For a zoom lens with such a wide range of focal lengths the DiMAGE 7's lens exhibited very little in the way of visible chromatic aberrations. On our test chart there was a very slight purple fringe but this really is at the bottom end of what we've seen (especially considering the resolution of the sensor).
Images re-saved to sRGB colour space [info]
|Visible chromatic aberrations in an "every day shot" (very few and far between)|
|Our now standard chromatic aberration test shot|
Barrel and Pincushion Distortion
The DiMAGE 7's lens also did well in our barrel and pincushion distortion tests. Considering its full wide angle is a very wide 28mm equiv. (something unusual for digital cameras) its measured an 1.3% barrel distortion is an excellent performance. Also at the telephoto end there's really very little pincushion distortion, 0.8% is very easy to live with.
|Barrel Distortion, 1.3% @ Wide Angle||Pincushion Distortion, 0.8% @ Full Tele|
Flat Area Noise
Quite early on (after we published some samples from an early pre-production camera) there was a lot of talk about noise in DiMAGE 7 images. Below you'll see a crop of the gray patches from our standard colour patch test chart. Yes, there's still some visible noise, it's not as smooth and clean as some we've seen, though it's certainly not a distraction or a fault.
|Red Channel||Blue Channel||Green Channel|
Breaking the patch down into red, green and blue components it's clear to see that most of the noise is isolated to the red channel (though there is still some visible in green and blue). It's certainly no more than we've seen from (say) Canon's G1 @ ISO 100.
The early production unit I used for this review did indeed have a stuck pixel, it was at location 1880,1635 and always showed as white (and of course had some knock-on effect on surrounding pixels).
|Full image||Stuck pixel cropped and magnified 400%|
The DiMAGE 7 offers fully automatic plus a set of pre-programmed white balance settings as well as the manual preset option. Overall the Auto mode worked best in natural light and the presets worked well in all light apart from Fluorescent (which is always tough because there are three or four different tube temperatures). The manual preset was pretty hard to fool and provided the most consistent white balance across different types of light.
|Outdoors, Auto||Outdoors, Cloudy||Outdoors, Manual|
|Incandescent, Auto||Incandescent, Incandescent||Incandescent, Manual|
|Fluorescent, Auto||Fluorescent, Fluorescent||Fluorescent, Manual|
Night (long) exposures
There has been talk of a noise reduction system on the DiMAGE 7, certainly looking at the results below it's clear that the camera can handle moderately long exposures and that there's very little 'hot pixel' noise for these long exposures. It's clear that the DiMAGE 7 is capable of taking nice, clean, night exposures.
|ISO 100, 4 sec, F4.0|
|ISO 200, 4 sec, F4.0|
|ISO 400, 4 sec, F4.0|
Dynamic range simply defines the range of light the camera is able to capture before it either loses detail in darkness (shadows for example) or blows out a highlight (edges of chromed metals are good examples of this). Most consumer digital cameras only have a 8-bit analog to digital converters, plus their CCD's are not built to have a particularly large dynamic range, Minolta state in their specifications that the DiMAGE 7 has a 12-bit ADC.
Using our new dynamic
range measurement method we measured the DiMAGE 7's dynamic range
as (higher numbers are better except for noise):
Minolta DiMAGE 7
* In-camera sharpening set to "Soft"
At ISO 100 results were quite similar to those of the Nikon Coolpix 990, at ISO 200 and 400 there's more dynamic range but roughly the same noise measurement.