Color (6.33)
Have you ever used a cheap digital camera with a sub-par imaging processor and found that your daughter's brown hair looks red or rustic in the pictures? Of course everyone wants to have perfectly accurate colors when they take pictures, but this color rendering ability is often overlooked when consumers are searching for that perfect camera. While some users may even desire the slightly over-saturated aesthetic that consumers are practically trained to expect, our tests evaluate the accuracy of the camera's portrayal of the natural scene--so if you don't want that over-saturated look after all, you know what models are best.
To test the color accuracy of this digital camera, we took several exposures of the industry standard GretagMacbeth color chart and uploaded the images into Imatest Imaging Software. The software then outlines the discrepancy between the camera's output and the corresponding ideal color. Below is a modified GretagMacbeth chart from the software. The outer square represents the colors produced by the Konica Minolta Z20. The inner square depicts the color corrected version that users would see in photo editing software or other computer application. The smaller vertical rectangle is the original ideal color from the color chart.
The same results from the modified chart are shown in the graph below. The circles represent the Z20's produced colors; the squares represent the ideal colors on the GretagMacbeth chart. The lines linking the two shapes indicate the degree of variance between the camera's produced tone and the ideal; the colors with shapes right on top of each other are the most accurate. The colors with shapes set farther apart are the least accurate.
The Konica Minolta DiMAGE Z20 received an overall color score of 6.33, which is almost identical to its counterpart, the Z5. The Konica Minolta Z5 received a score of 6.34. Both cameras produce colors that stray significantly from the ideal. This means that there is a significant variance in the perceived scene (by the human eye) and the reproduced image recorded by the Z20. Much of this alteration is due to a strong over-saturation of red and pink tones (earning a 105.7% mean saturation score), which is aesthetically pleasing to many (but not all). It really is important to determine what is desired in the camera: if you prefer a naturalistic representation of the scene, the Z20 is not for you; although if you are looking for a camera that applies a band-aid of sorts to add interest to gray or flat scenes, the Z20 may be a suitable counterpart.
Still Life Scene
Below is our awesome still life scene recorded by the Konica Minolta DiMAGE Z20.
Click on the above image to view a full resolution version (CAUTION: The linked image is very large!)
Resolution / Sharpness (4.10)
The DiMAGE Z20 is advertised by Konica Minolta as having 5.2 total megapixels on its 1/2.5-inch CCD. Of those megapixels, only 5 of them are intended to be used in capturing images. As some imagers are more efficient then others, we test each camera to determine how many pixels are actually used in capturing. We do this by taking several exposures of an ISO 12233 resolution chart and uploading those pictures into Imatest Imaging Software, which assesses the utilized pixels. We compare the amount of active pixels to the advertised count and assign a percentage score based on the contrasting values. Cameras earn a "good" score if it rates beyond 70 percent of the marketed resolution count, a "very good" score if it exceeds 80 percent, and an "excellent" score for anything surpassing 90 percent.
The Konica Minolta Z20 used 4.1 of its advertised 5 effective megapixels, earning a "very good" resolution score, as it utilized 83 percent of its advertised count. These results are similar to the 5-megapixel Z5, which used 3.98 - or about 81 percent - of its advertised count. Now let me say something about what you really need megapixels for. Most cameras exceeding 3.0 (actual used) megapixels will be adequate for making up to 8 x 10 prints. If users are frequently printing on 8 x 10-inch paper, I would suggest moving up to 4 or 5 megapixels, so cropping images is an option. The 4.1 active megapixel count of the Konica Minolta Z20 will hold up strong among the compact camera competition, and it could create prints that rival the sharpness and definition of some less effective imagers that claim to have 7.1 effective megapixels.
Noise-Auto ISO (1.85)
Once again, this DiMAGE Z20 performed right on par with the Z5, which unfortunately, in terms of noise suppression, is not a good thing. We tested the noise levels using the auto ISO setting, allowing the Z20 to determine the appropriate ISO rating. Even though we were shooting in bright light (well beyond 3000 Lux), the camera selected the 160 ISO setting. Under the same conditions and equal amount of visible light, most compact digital cameras will opt for an ISO setting under 100, so this was an abnormal response to the condition, but again, in this respect the Z20 performed on-par with its sibling, the DiMage Z5. The fact that the Z20's automatic ISO range extends from 50-160 and that the camera selected the highest ISO setting in abundant lighting is quite disturbing. Because of this miscalculation, the Konica Minolta Z20 received an automatic noise score of 1.85. It is not recommended to use the automatic ISO setting, as it seems to have an illogical mind of its own. Users are much better off manually adjusting the ISO ratings.
Noise-Manual ISO (5.49)
This camera offers four manual ISO ratings: 50, 100, 200, and 320. We tested noise levels at each rating and compiled the results into a regression analysis to determine the overall score. The Konica Minolta Z20 received an overall manual noise score of 5.49, which is far better than its automatic score and even surpassed the Z5's score of 3.95. This score reinforces the recommendation that users should manually adjust the ISO rating rather than rely on the camera's automatic settings. When this "extra" step is taken by the user, far cleaner images can be captured in more compromised lighting. Resulting noise at each ISO rating can be seen in the chart below. The horizontal axis represents the camera's ISO ratings, while the vertical axis represents the noise produced by the Konica Minolta DiMAGE Z20.
Low Light (7.5)
We test each camera's low light performance to determine how effective the imager is without the assistance of added light or the flash. This is done to isolate the sensitivity of the imager and determine the light level at which the camera is rendered useless. We test low light performance using the camera’s highest ISO rating (ISO 320), and record four images at decreasing light intervals: 60, 30, 15, and 5 Lux. These increments are selected as a means of reproducing common low light levels; 60 Lux appears as a bedroom might after dusk, while 30 Lux correlates to a single 40 watt lightbulb, and 15 and 5 Lux approach darkness.
|
Low Light Tests
|
 |
 |
|
60 Lux
|
30 Lux
|
 |
 |
|
15 Lux
|
5 Lux
|
Click on any of the above charts for additional image analysis
Surprisingly, without image stabilization and a slightly weaker lens, the Konica Minolta DiMage Z20 outperformed its more expensive counterpart, the DiMage Z5, in low light. Much of this feat can be attributed to the Z5’s inability to focus when light levels dropped below 30 Lux. This problem did not occur with the Z20. Even at 5 Lux, the Z20 recorded a clean, moderately visible image.
The drop from 30 Lux to 15 Lux yields a significant loss of quality when shooting with the Z20, as colors lose vibrancy and became washed out as noise notably increases. While most cameras will display a significant loss of quality under 60 Lux, not many will capture discernible images with such a clear differentiation of color tones. A night scene or skyline would certainly be clearly visible with the Z20, portraying all tonal gradations with significant clarity – the only issue is the pixillated rendering of noise that accompanies the imagery.
Speed / Timing
Start-up to First Shot (8.59)
The Konica Minolta Z20 advertises a half-second startup time, but I found the camera to be a much slower on its first shot. It took this model 1.41 seconds to start up and take the first shot each time we tried it.
Shot to Shot (7.6)
The burst mode was rather disappointing on the Z20, taking 1.7 seconds in between pictures for three shots, then requiring a 10-second nap before its next burst. This was when the camera was in the Continuous setting. The Progressive takes a shot every 1.5 seconds and saves the last 6 shots, which is slightly better, but still far short of what other models in this price range are doing.
Shutter to Shot (6.4)
Let's hope your subjects can stand still for a long time and keep their eyes open. This camera took 1.03 seconds from the time the shutter was pressed to capture the image.
