Digital Cameras - Pentax Optio 230 Test Images
(Original test posting: 06/26/02)
| I've begun including links in our reviews to a Thumber-generated index page for our test shots. The Thumber data includes a host of information on the images, including shutter speed, ISO setting, compression setting, etc. Rather than clutter the page below with *all* that detail, I'm posting the Thumber index so only those interested in the information need wade through it! |
| Outdoor Portrait:
The extreme tonal range of this image makes it a tough shot for many digicams, which is precisely why I set it up this way. The object is to hold highlight and shadow detail without producing a "flat" picture with muddy colors, and on the whole, the Optio 230 handles the challenge pretty well. The shot at right was taken with a +0.7 EV exposure compensation adjustment, which brightened the midtones at the expense of lost highlight detail. - It's really a bit overexposed, but the shot at +0.3 EV was quite a bit underexposed, so I elected to go with the brighter shot and give up some highlight detail. I shot with the Auto white balance setting, which is just a hint warm. The Daylight setting resulted in a similar shot, and the Manual setting produced a slightly warmer color balance. Skin tones look pretty good, but the blue flowers are dark and rather purplish (a common problem with this shot). Resolution is moderate, and details are just a hint soft. The shadow areas show good detail, with only moderate noise. |
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In retrospect, I should have also taken a shot here with a little negative exposure compensation dialed in, as this shot is really just a bit too bright. (Given my experience above though, I suspect it might have come out too underexposed.) Overall results are similar to the wider shot above, and the Optio 230's 3x zoom lens helps prevent distortion of Marti's features. Fine detail increases in her face and hair, though details are again slightly soft. The shadow areas show a nice level of detail, and noise is minimal. To view the entire exposure series, from zero to +0.7 EV, see files P23FACAP0.HTM through P23FACAP2.HTM on our thumbnail index page. |
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Underexposed at the default exposure, but good results with a little EV boost. The Optio 230's flash illuminated Marti pretty well here, though intensity was a little low at the default exposure. A slight orange cast appears on the back wall from the household incandescent lighting, but doesn't affect the white of Marti's shirt too strongly (some orange tints are present on her shoulders and in her hair though). Increasing the exposure compensation to +0.3 EV brightens the shot significantly, though it nearly loses the highlight detail in Marti's shirt. The orange cast decreases with the brighter exposure, and color still looks good. Out of curiosity, I also shot an image at -0.3 EV, which resulted in a stronger orange cast and barely any illumination on Marti at all. |
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Strong color casts, though the Incandescent white balance performs well. This shot is always a very tough test of a camera's white balance capability, given the strong, yellowish color cast of the household incandescent bulbs used for the lighting. The Optio 230 had some trouble here, and produced strong, orange color casts with the Auto and Manual white balance settings. Though the Incandescent setting has a slight warm tint, it produced the most accurate color. An interesting note here is that the color cast varied quite a bit as a function of the exposure compensation setting. As I increased the exposure compensation from zero to 1.3, the color ranged from greenish through yellow, to somewhat pink. The blue flowers appear purple from the warm cast, a common problem with this shot. Skin tones look good however. The main shot has a +1.3 EV exposure compensation adjustment. Following are links to an ISO series and to the full exposure series. To view the entire exposure series from zero to +1.3 EV, see files P23INTP0.HTM through P23INTP4.HTM on the thumbnail index page. ISO Series
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Moderate resolution and detail, but nearly accurate color. All three white balance settings produced slight color casts on this shot. Auto resulted in a slight red tint, while Daylight had a yellow cast. (Both images were a bit warm.) The Manual white balance resulted in a slightly cool color balance. I chose the Manual setting for the main shot, as overall color looked best. The red bricks were too saturated in both the Auto and Daylight settings. Resolution is moderate, though detail in the shrubbery in front of the house is full of noticeable artifacts. Details are slightly soft throughout the frame, with slightly increased softness in the corners.
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This image is shot at infinity to test far-field lens performance. NOTE that this image cannot be directly compared to the other "house" shot, which is a poster, shot in the studio. The rendering of detail in the poster will be very different than in this shot, and color values (and even the presence or absence of leaves on the trees!) will vary in this subject as the seasons progress. In general though, you can evaluate detail in the bricks, shingles and window detail, and in the tree branches against the sky. Compression artifacts are most likely to show in the trim along the edge of the roof, in the bricks, or in the relatively "flat" areas in the windows. This is my ultimate "resolution shot," given the infinite range of detail in a natural scene like this, and the Optio 230 captures limited fine detail throughout the frame. The tree limbs above the roof and the shrubbery in front of the house show moderate detail, but details throughout the frame are rather soft, particularly when compared with the best-performing cameras in the two megapixel category. The corner softness I saw in some of the studio shots isn't apparent in this test. The camera loses practically all detail in the bright white paint around the bay window, tricked by the harsh sunlight. Alternatively, the brick pattern above the front door is distinct, indicating that the Optio 230 does a good job with the shadow detail here. Color looks good under the Auto white balance setting, though the green values are a bit yellowish. The table below shows a our standard resolution and quality series, followed by ISO, Contrast, Sharpness, and Saturation series. Click here for a sample image in Black & White mode. Resolution Series:
ISO Series:
Contrast Series:
Sharpness Series:
Saturation Series:
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Lens Zoom Range A typical 3x zoom range. I routinely shoot this series of images to show the field of view of each camera, with the lens at full wide angle, at maximum telephoto (3x, in this case), and at full telephoto with the digital zoom enabled. The Optio 230's lens is equivalent to a 38-114mm zoom on a 35mm camera. Following are the results at each zoom setting.
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Some difficulty with color casts, but good resolution. This shot is generally a tough test for digicams, as the overabundance of blue in the image often tricks white balance systems into producing a warm color balance. The Optio 230's white balance system fell victim to the trap, as both the Auto and Daylight settings resulted in very warm color balances. The Manual setting produced a reddish cast, but I chose it as the main image because the skin tones looked the most natural here. Despite the red cast, which results in a purplish-blue background, overall color looks nearly accurate. The blue robe has purple tints in the shadow areas, but this is not uncommon for this shot among digicams I've tested. Resolution is moderate, and the embroidery of the blue robe shows good detail. |
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Excellent macro performance, with great flash coverage. The Optio 230 performed very nicely in the macro category, capturing a tiny minimum area of just 1.64 x 1.23 inches (41.7 x 31.3 millimeters). Resolution is high, with a lot of visible detail on the coins, brooch, and dollar bill. Details are just a little soft, however. Color and exposure both look good, though the Auto white balance results in a warm cast. The Optio 230's flash had no trouble throttling down for the macro area, with good, even exposure throughout the frame. (The very top of the frame is a little hot, but overall a great performance at this close range.) |
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"Davebox" Test Target
Good exposure and color. Both the Auto and Manual settings produced nearly accurate shots, though I chose the Manual setting as the best overall. (The Auto setting had a slight reddish tint in the white values.) As you might expect, the Daylight white balance produced a warm color balance, but wasn't too strong. Exposure looks about right, and the camera picks up the subtle tonal variations of the Q60 target nicely. The large color blocks look good as well, and saturation is about right. Detail is good in the shadow area of the charcoal briquettes, with moderate noise. The entire image is slightly soft, but the level of visible fine detail is good. Really excellent color and tonality on this shot! |
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Low-Light Tests Just sensitive enough for night shots under average city street lighting. The Optio 230 has a maximum shutter time of four seconds, which limits the camera's low-light shooting abilities slightly. The camera captured bright, clear images at light levels as low as one foot-candle (11 lux), at both 100 and 200 ISO settings. The target remained visible, though just slightly dim, at 1/2 foot-candle (5.5 lux), and could be used if brightened with imaging software. Typical street lighting on a city street is equivalent to about one foot-candle, so the Optio 230 should work well for city night scenes, but will need its flash for anything darker. Color is about right, though slightly warm from the Auto white balance, and noise is moderately low. The table below shows the best exposure we were able to obtain for each of a range of illumination levels, at each ISO setting. Images in this table (like all of our sample photos) are untouched, exactly as they came from the camera.
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Flash Range Test Low intensity, but consistent to 14 feet. The Optio 230's flash seemed to underexpose the target on this test, even at the shortest distance from the test target. Overall brightness remained about the same all the way out to 14 feet, with only a slight decrease in intensity. Hard to figure how to rate it - Little falloff out to 14 feet, but it's really too dim at shorter distances. (Seems powerful enough, but you need to dial-in quite a bit of positive exposure compensation.) Below is our flash range series, with distances from eight to 14 feet from the target.
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ISO-12233 (WG-18) Resolution Test
The Optio 230 performed about average on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 550 lines per picture height vertically and horizontally. I found "strong detail" out to at least 800 lines. "Extinction" of the target patterns occurred at about 1,000 lines. Optical distortion on the Optio 230 is higher than average at the wide-angle end, where I measured barrel distortion of 1.06 percent. The telephoto end fared a little better, with 0.39 percent barrel distortion. This is a good bit higher than average geometric distortion at both ends of the zoom range. Chromatic aberration is virtually nonexistent though, showing about one or two pixels of extremely light coloration on either side of the target lines. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.) Resolution Series, Wide Angle
Telephoto
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Viewfinder Accuracy/Flash Uniformity An optical viewfinder that ranged from a little tight to rather loose, but very accurate LCD monitor. The Optio 230's optical viewfinder is a little tight at wide angle, where I measured an approximate 89 percent frame accuracy. At telephoto, the viewfinder was actually very loose, showing much less of the subject area than what was framed. I couldn't take any measurements on this shot, as the standard lines of measurement were cut out of the frame. The LCD monitor fared much better, as I measured about 96 percent frame accuracy at wide angle, and about 95 percent at telephoto. Given that I generally prefer LCD monitors to be as close to 100 percent accuracy as possible, the Optio 230 performs very well in this respect. Flash illumination at wide angle is dim and somewhat uneven, with moderate falloff in the corners of the frame. At telephoto, flash distribution is quite even, but rather dim.
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