Minolta DiMAGE A1 Review
The DiMAGE A1's automatic white balance performance was pretty much perfect in natural light but suffered from the all to familiar yellow cast under incandescent and fluorescent light. While the natural light presets were accurate enough the incandescent and fluorescent presets weren't near enough to our test lamps (although obviously with the A1 you can fine tune each preset). Manual preset white balance was as expected perfect.
|Outdoors, Auto||Outdoors, Cloudy, Sunny/Shade||Outdoors, Manual|
|Incandescent, Auto||Incandescent, Incandescent||Incandescent, Manual|
|Fluorescent, Auto||Fluorescent, Fluorescent||Fluorescent, Manual|
White Balance Fine Tuning
With the advent of the DiMAGE A1 Minolta has chosen to improve white balance flexibility by adding the ability to fine tune each of the preset white balance settings. Simply turn the rear dial while holding the function button (in the WB position) and you can tune the selected preset from -3 to +3. The example below was shot in incandescent light and shows that the +3 setting is more accurate.
|Incandescent -3||Incandescent +0||Incandescent +3|
The DiMAGE A1 has two macro positions on its lens, one at wide angle and one (with a little zoom adjustment) at telephoto. Both proved to have the same minimum focus distance and so (in my opinion) the wide angle macro option is fairly pointless, it doesn't provide you with any close-up frame coverage and simply introduces a lot of distortion (Minolta should just do away with it). Instead the telephoto macro option provides respectable close up shots with high magnification and no distortion (other than a little corner softness at a wide open aperture). The macro tests below are using our new macro focus test chart and measurement system; each line on the grid is 10 mm, taken at shortest subject distance in each macro mode.
|Wide angle - 293 mm x
220 mm coverage
9 px/mm (221 px/in)
Corner softness: Low
|Telephoto - 49 mm x 37
51 px/mm (1301 px/in)
Corner softness: Average
The DiMAGE A1 performed well in our flash tests, both shots below were taken in Program AE (P) mode with Auto ISO selected. As you can see the camera wasn't fooled by the light background in our skin tone test and also delivered natural skin tones with no color cast. Overall a good performance, Kudos Minolta.
|Skin tone - Natural color, no blue cast, good exposure (Auto ISO; ISO 200)||Color patches - Good color balance, no color cast, good exposure (Auto ISO; ISO 200)|
The DiMAGE A1 has manually selectable dark frame noise reduction for long exposures. As you can see from the samples below it needs it. With noise reduction turned off long exposures are covered in 'hot pixel' noise speckles, even with the noise reduction enabled not all noise is removed and there is quite a bit of 'black pitting'. Not a fantastic performance considering the target market.
|Manual exposure: ISO 100, 30 sec, F11, Noise reduction: Off|
|Manual exposure: ISO 100, 30 sec, F11, Noise reduction: On|
Barrel and Pincushion Distortion
As expected (the lens is the same) the DiMAGE A1 produced exactly the same amount of lens distortion as the DiMAGE 7 series. At full wide angle you can expect 1.3% barrel distortion and at telephoto you can expect 0.8% pincushion distortion (hardly noticeable).
|Barrel Distortion, 1.3% @ wide angle||Pincushion Distortion, 0.8% @ telephoto|
Vignetting / Lens Shading
Our vignetting / lens shading test is very simple, a shot of a blank wall from two meters away, vignetting will always be most visible at wide angle and maximum aperture and will start to disappear at smaller apertures and/or further zoom. While the DiMAGE A1 did exhibit some very slight lens shading at both wide angle and telephoto it's really not enough to be visible in every day shots and is actually a good performance considering the zoom range.
|Very slight lens shading visible at wide angle, F2.8||Very slight lens shading visible at telephoto, F3.5|
Purple Fringing (Chromatic Aberrations)
We observed very little purple fringing in every day shots taken with the DiMAGE A1. As noted above the same lens as the DiMAGE 7 series with the same characteristics. We found it very hard to even find a single example of purple fringing from our samples.
|[To do - will add today]|
|Hard to find fringing in every day shots, F2.8||Our standard chromatic aberration test shot|
Overall Image Quality / Specific Issues
Comparing the DiMAGE A1's images to the DiMAGE 7Hi (the camera it supersedes) it's clear that Minolta's engineers have spent some time tweaking the image processing algorithms. Specifically noise is lower, especially in shadow areas at ISO 100 (one niggle we had with the 7Hi). The DiMAGE A1 delivers images which are not overly contrasty, not oversaturated and have neutral sharpening. Minolta appear to be aiming for a 'film like' unprocessed appearance to their images.
That's not to say everything is rosy, on fine detail we did observe some (slight) Bayer interpolation artifacts and other odd artifacts as noted below.
Image Processing artifacts
After shooting our resolution chart target with the DiMAGE A1 we did note some odd image processing artifacts. These all appear to be tied to the camera's built-in Bayer interpolation, noise reduction, sharpening and image processing algorithms. I say this because most of these effects disappear if you shoot RAW and convert the image using DiMAGE Viewer. The only artifact occasionally visible in every day shots was moiré at resolution limits.
|Less resolution than most other five megapixel prosumer digital cameras||Moiré visible at resolution limits *|
|Beat dots between mid-frequency slanted lines **||Noise reduction induced errors between mid-frequency horizontal lines **|
|Thunderheads With Egret by Buzz Lightyear|
|Double Rainbow; Abiquiu, NM, USA. by abiquiuense|
from After the Rain