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- Pentax Optio A30
- Read an expert, independent digital camera review of the Pentax Optio A30.
Pentax Optio A30 Digital Camera Review
Read an expert, independent digital camera review of the Pentax Optio A30.
Testing / Performance
We tested the color accuracy of the Pentax A30 by photographing an industry standard GretagMacbeth ColorChecker test chart. The ColorChecker consists of 24 tiles of different colors, including sky blues, grass greens, and flesh tones. We ran the images through Imatest to compare the colors the camera reproduced with the actual known colors of the test chart. The image below compares the camera's rendered colors with the actual colors of the chart. In each color tile, the outside squares are the colors the camera reproduced, the inside squares are the actual colors of the chart corrected for the exposure, and the small inside rectangles are the actual colors of the chart at a perfect exposure.
Comparing the inside squares to the outside squares shows a number of differences in color, most strikingly in the yellows and reds. The actual color error is shown more quantitatively in the chart below. Overlaid on the color spectrum, the squares indicate the location of the ideal colors, while the circles indicate the colors the camera reproduced. The color error is shown by the lines connecting the circles and squares; the longer the line, the more inaccurate the color.
Manufacturers will often boost or shift certain colors to make photos look better. For example, blues are often shifted to make clear skies look more brilliant. The problem is, when colors are shifted by the camera, users will never know what they really were, and color correction in post-processing will be limited.
As you can see in the color spectrum graph, many of the colors are shifted from their ideal values, especially yellows and blues. Since the yellows are shifted green, this could lead to unpleasing portrait shots. There is also a general trend to undersaturate colors, which means colors won’t "pop" without adjusting the saturation in post production. Overall, the A30 shifts colors a bit more than we would like to see.
*Pentax touts resolution as one of the 10.1-megapixel A30’s main selling points. We put the camera to the test by photographing an industry standard resolution test chart, and running the images through Imatest to determine how much detail the camera could truly discern. Imatest measures resolution in terms of line widths per picture height, which refers to the number of evenly spaced, alternating black and white lines that could fit in the picture frame before becoming blurred.
The A30 takes the sharpest images at ISO 64, f/4.8, and a focal length of 19mm. In our tests, the camera resolved 1839 lw/ph horizontally with 5.7 percent oversharpening, and 2019 lw/ph with 19.4 percent percent oversharpening vertically.
These resolution numbers are quite impressive, except for the substantial vertical oversharpening. Cameras automatically sharpen images in order to make them appear more crisp right out of the camera. The problem with too much sharpening (especially in high megapixel cameras) is that it can introduce unwanted, ugly artifacts that hide real visual information. The 19.4 percent vertical oversharpening in the Pentax A30 is much more than necessary, and if you look at the high resolution image of the resolution chart you can see white "ghosting" lines. These lines will be noticeable along edges of high contrast in large prints. Despite this issue, the A30 has impressive resolution and scored above average compared to other 2007 point-and-shoots. It scored better than the similarly priced Canon PowerShot SD750 and Sony Cyber-shot T100, though not as well as the Fujifilm FinePix F40*fd*.
**Noise – Manual ISO ***(5.71)
*"Noise" refers to the random signal noise produced by a camera’s sensor. It is the equivalent of the static in a TV set, or the background hum from a stereo system. We test a camera’s noise levels by shooting our test chart at all full resolution ISO levels. The A30 has a sensitivity range from ISO 64-1600. Due to the physics of camera sensors, the higher the ISO sensitivity, the more noise is visible in the image.
As you can see in the graph above, the A30 breaks the golden rule. Noise rises quickly up to ISO 800, and then drops at ISO 1600. Have Pentax engineers broken the laws of physics? Alas, they have not, at least for now. What is actually going on, as given away by closer inspection of the test images, is that more noise reduction is being applied at ISO 1600. This noise reduction smoothes over the noise, which removes some of the ugly splotchiness, but in turn greatly reduces the amount of detail. This is evidence that the ISO 1600 setting is too much for the A30 to handle, and should be used sparingly. Keep the ISO as low as you can with this camera.
Noise – Auto ISO*(1.19)*
To test a camera’s Auto ISO, we photograph the same chart under bright studio lights. At the ISO 400 setting, the camera yields an unfortunately high level of noise. Noise covers 1.77 percent of the image, which is clearly visible as ugly color splotches distributed evenly throughout the picture. Because of these high noise levels, the A30 scored very poorly in this test.
*Auto (5.96) *
Accurate white balance is critical for taking nice photos, unless you like an odd color cast to your pictures. We test white balance by photographing the ColorChecker test chart under four different types of light: flash, fluorescent, outdoor cloudy, and tungsten. We photograph the chart with both the auto white balance setting and the white balance presets. The auto setting is actually more accurate than the fluorescent preset under white fluorescent light. However, the A30 does not have a flash preset, and this is very unfortunate because the auto white balance was quite inaccurate with the flash.
*Preset (8.61) *
The A30 is more accurate under cloudy outdoor light and tungsten light using the presets rather than auto white balance. This is also true in tungsten light, where the auto white balance is terrible, but excellent using the tungsten preset. With the exception of fluorescent, this camera’s presets are more accurate than auto white balance and should be used most of the time.
***Click to view the high-resolution image.*
**Low Light ***(6.50)
*In order to get a look at how a camera performs in different lighting conditions, we dim the studio lights and test the camera’s ability to perform in low light. We photograph the ColorChecker at light levels of 60, 30, 15, and 5 lux. 60 lux corresponds to the light levels of a room softly lit by two lamps, 30 lux corresponds to a room illuminated by a single 40 watt bulb, and 15 and 5 lux are very low light that test the limits of the sensor.
When set to ISO 1600, the A30 does not expose properly at 5 lux, proving that the sensor is limited in low light. Color accuracy also does not hold up well in low light; at 60 lux the mean color error is 13.7 and the saturation is 118 percent, which is too much color saturation for shooting with default color settings. However, noise levels stayed admirably low, only reaching about 1.6 percent, which is great for ISO 1600. Yet, as we discussed in the Noise section above, the low noise levels come at the expense of sharpness and detail.
We also test a camera’s long exposure performance in low light. In Manual and Shutter Priority modes, the A30 take exposures up to 4 seconds in length. At exposures longer than 1 second, the camera has mediocre color accuracy but good saturation levels. Noise, on the other hand, is higher at ISO 400 long exposures than at ISO 1600 as described above.
Dynamic Range* (6.34)*
Dynamic range is a measure of the range of tonal values a camera can distinguish. Good dynamic range means you will be able to see more detail in very bright and dark areas of your photos. We test dynamic range by photographing a backlit Stouffer test chart and running the images through Imatest to objectively measure the number of discernable tonal steps. The Stouffer chart is made up of a long row of rectangles of various shades of gray, from brightest white to darkest black. The more rectangles the camera can distinguish, the better the dynamic range.
At ISO 64 and 100, the Pentax A30 does an excellent job with dynamic range, detecting almost 7.5 Exposure Values (EV). Note that these specific values are under ideal shooting conditions, so you will probably not be able to see the full 7.5 stops in your own photos. That said, the camera performs better than most other point-and-shoots we tested this year. As you can see in the graph, the dynamic range falls off steadily at higher ISO sensitivities, so it is ideal to keep the A30 at low ISO setting whenever possible.
Speed/Timing – All speed tests were conducted using a Kingston Ultimate 2GB 120X SD Card.
Startup to First Shot (7.9)
The A30 takes 2.1 seconds to take a picture after it is turned on. This is torturous and could result in a missed shot if the camera isn't left on.
In Continuous Shooting mode, the A30 takes one shot approximately every 0.9 seconds. This number is approximate because the time between shots actually varies, from 0.7 seconds to as long as 1.4 seconds. Still, this speed lasts for 250 full resolution shots, which is impressive.
*The Pentax has no lag between pressing the shutter and recording a picture when it is already prefocused. Without being prefocused, the camera takes a shot in 0.1 seconds.
It takes the A30 2.6 seconds to process one full resolution 4MB shot taken at ISO 200. This is a pretty slow processing time, so if you need to take shots quickly, be sure to put the camera into Continuous shooting mode.
The Pentax A30 is one of the very few cameras on the market today that shoots video in DivX format. Normally used as a flexible format to compress large video files recorded in other formats, DivX is the only video format the A30 can shoot, and has only two file size options available in the camera. The benefit of DivX video is significantly smaller file sizes. Read on to see how the A30’s DivX video performed in our lab and field testing.
Bright Light – 3000 lux
We record video of our color charts under bright studio lights lit evenly to 3000 lux. With the camera set to auto white balance, the A30’s video color accuracy is horrendous, as you can see in the images below. Saturation was off the charts, at 149 percent.
*Low Light – 30 lux *
We dimmed the studio lights and recorded more video of our color charts at 30 lux. In low light, the color accuracy is still poor, but this is normal for a camera set to auto white balance when shooting under tungsten lights. Saturation is much better than in bright light, and noise levels stay reasonably low.
We also shoot video of our resolution test chart at 1700 lux. The A30 has trouble resolving detail, and only manages 219 lw/ph horizontally with 5.7 percent undersharpening, and 325 lw/ph vertically with 17.1 percent oversharpening. Look at the crops below to see how much artifacting is introduced by the sharpening and the DivX compression. Do you want your video to look like this?
We left the lab and took the A30 outside to record some movement on the streets. The A30’s DivX compression is really apparent when recording moving objects. Moving objects have horrible color moiré, extremely jerky motion, and very poor detail. There is abundant image artifacting, and the exposure changes on a whim, making the video blink bright and dark without any way to control it. Dynamic range is very poor, especially in the dark areas, where the camera could make out very little detail. Overall, the A30 is one of the worst performing cameras of the year in terms of video performance. The space you’ll save on your hard drive with the A30’s DivX video is not worth the very poor video quality the camera records.