Digital Cameras - Pentax Optio 555 Test Images
|I've begun including links in our reviews to a Thumber-generated index page for the test shots. The Thumber data includes a host of information on the images, including shutter speed, ISOsetting, compression setting, etc. Rather than clutter the page below with *all*that detail, we're posting the Thumber index so only those interested inthe 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, and why I shoot it with no fill flash or reflector to open the shadows. The object is to hold both highlight and shadow detail without producing a "flat" picture with muddy colors. The Optio 555 did a pretty good job of it, although its default color was a little less saturated than that of many consumer cameras, and its default contrast was somewhat high.
The shot at right was taken with a +0.7 EV exposure compensation adjustment, with the contrast control set to low and the saturation control set to high. The result is a significant taming of the excessive contrast seen with the default contrast and saturation settings, and only slightly oversaturated color. Overall, a very pleasing result. (See below for side-by-side comparisons showing the impact of the contrast and saturation adjustments.) I chose the Auto white balance as the most accurate overall, though the Manual setting also produced nice results. The Daylight setting was slightly warm, with a yellow cast.
In the contrast/saturation-adjusted image, skin tones look good, though maybe slightly pink, but the blue flowers in the bouquet are rather dark and purplish. (This is a difficult blue for many digicams to get right, and in reality is a light navy blue with just hints of purple in it.) Color looks good throughout the rest of the frame, although the saturation boost left the color saturation slightly high. Resolution is very high, and details are strong in Marti's features as well as in the flower bouquet. Shadow detail is also strong, with surprisingly low noise.
To view the entire exposure series from zero to +1.0 EV, see files O55OUTAP0.HTM through O55OUTAP3.HTM on the thumbnail index page.
Here's a set of four shots, showing the effect of the contrast and saturation adjustments, applied both separately and together. Both cover a useful range of adjustment, enough to make a difference, but not so much as to produce garish results.
Excellent resolution and detail, similar tonality to the above.
Exposure and color are fairly similar to the default wide shot above, with slightly high contrast and muted color. (I chose the default contrast and saturation settings for this shot, and also felt that no exposure compensation was called for.) Although slightly dark, the midtones show good detail. The Optio 555's 5x lens does a good job preventing distortion of Marti's features. Resolution and detail are even better in this close-up shot, with great definition in Marti's face and hair, as well as in the subtle textures of the house siding behind her.
To view the entire exposure series from -0.3 to +1.0 EV, see files O55FACAP0.HTM through O55FACAP2.HTM on the thumbnail index page.
Indoor Portrait, Flash:
A lot of exposure compensation required to produce a good exposure, some orange cast from the household lighting.
The Optio 555's flash illuminated the subject quite well with a +1.7 EV exposure compensation adjustment, but this is a lot more adjustment than is required by most cameras for this shot. (The shot at the default exposure was quite dim.) With the heavy exposure adjustment, flash intensity is good, with good coverage on Marti's features. The strong incandescent lighting in the room creates an orange cast on the back wall, which creeps onto Marti's hair and parts of her face, as well as portions of the white shirt. Overall color is still pretty good, despite the orange cast. I also shot in the camera's Shutter Priority exposure mode, at 1/25 second with a +1.7 EV exposure compensation adjustment, to mimic the "slow sync" auto mode provided by some cameras. The slower shutter speed allows more ambient light into the image, which produces more balanced lighting. (Though the orange cast is stronger on Marti's face and shirt.)
Indoor Portrait, No Flash:
Good color with the Manual and Incandescent white balance settings, good exposure as 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 555's Auto white balance setting fell victim to the trap, producing a strong orange cast. The Incandescent and Manual white balance settings both produced good results, although I preferred the warmer cast of the Incandescent setting over the slightly green cast of the Manual setting. The main shot was taken with a +1.0 EV exposure compensation setting. Color looks good, with nearly accurate skin tones on Marti's face and hands. The blue flowers are dark and purplish, but this is a common problem with this shot, due to the warm cast of the source lighting.
Great resolution and detail, but some difficulty with the color balance.
The Optio 555's Auto white balance setting produced the best overall results here, despite a very slight warm cast. I preferred it to the much cooler cast of the Manual setting, and the very warm, yellow cast of the Daylight setting. Resolution is very high, and detail is strong in the tree limbs above the roof, as well as in the shrubbery in front of the house. (The Optio 555's five-megapixel CCD actually stretches the limits of this poster as a test target. Even though the poster was made from a 500MB scan of a 4x5 negative shot with a tack-sharp lens, the 555 extracts almost all of the detail that's to be found here.) Details are sharp most of the frame, with only the slightest corner softness in the top left corner.
Very nice resolution and detail, with good color.
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 555 captured quite a bit of detail throughout the frame. The tree limbs over the roof and fine foliage in front of the house have strong detail in the leaf patterns, and the bricks and house trim look good as well. Details are crisp and clear throughout the frame, with very little softening in the corners, and very little evidence of chromatic aberration. (The 555's lens appears to be of unusually high quality.) The camera picks up some detail in the bright white paint surrounding the bay window, a trouble spot for many digicams, but most of the area is blown out. Detail is moderate in the shadow area above the front door as well, with moderate noise. (Overall, this shot would have benefitted greatly from a contrast/saturation adjustment of the sort I used on the Outdoor Portrait shot above, but I generally capture this shot with each camera's default settings (adjusting only exposure), to show more what the camera's basic capabilities are.) The Auto white balance setting did a good job here, producing an accurate white value on the house trim and good overall color. The table below shows a standard resolution and quality series, followed by ISO, sharpness, contrast, and saturation series.
Lens Zoom Range
Excellent 5x zoom range.
I routinely shoot this series of images to show the field of view for each camera, with the lens at full wide angle, at maximum telephoto (5x, in this case), and at full telephoto with the digital zoom enabled. The Optio 555's lens is equivalent to a 37.5-187.5mm zoom on a 35mm camera. That corresponds to a moderate wide angle (a bit less wide at the wide angle end than the 35-105mm range found on many 3x zoom cameras) and a pretty substantial telephoto. Following are the results at each zoom setting.
Slight color casts with each white balance setting, Manual is best overall, but rather blue-looking. Excellent resolution.
This shot is often a tough test for digicams, as the abundance of blue in the composition frequently tricks white balance systems into producing a warm color balance. Each of the white balance settings I tested here produced color casts, but I eventually settled on the slightly cool Manual white balance for the main shot. Skin tones were much too warm with the Auto setting, and the Daylight setting had a strong yellow cast. Skin tones are quite pale with the Manual white balance, but the most believable. The blue robe is about right, with only slight purplish tints in the deep shadows. Resolution is excellent, and the embroidery of the blue robe shows a lot of fine detail. (The original data file for this poster was only 20MB though, so cameras like the Optio 555 are capable of showing much more detail than the poster has in it.)
A slightly large macro area, but excellent detail and resolution.
The Optio 555 captured a slightly larger than average macro area, at 3.98 x 2.99 inches (101 x 76 millimeters). Resolution is very high however, with excellent detail in the coins, brooch, and dollar bill. Even the tiny dust particles on the coins are clearly visible. All four corners are fairly soft though, with the softness extending down both sides of the frame. Most digicams I test tend to have some softening in the corners of the frame on macro shots, but the 555's macro mode shows the problem more than most. The Optio 555's flash throttled down well for the macro area, with only slight reflections in the coins. Overall, not a terrible macro performance, but if ultra-close macros are a primary need for you, the 555 wouldn't be your best choice.
Slightly dark exposure, and a tendency toward a warm color cast, but good color rendition.
The Optio 555's Manual white balance setting produced the best results here, as the Auto and Daylight settings resulted in warm images. (The Auto setting had a reddish tint, while Daylight had a yellow cast.) The images are just slightly underexposed, giving the large, white color block a somewhat dull appearance. However, the camera distinguishes the subtle tonal variations of the Q60 target very well. The large color blocks are also a little dull and dark-looking, but there's reasonable detail in the shadow area of the charcoal briquettes, with moderate image noise, and the colors are generally pretty accurate.
Outstanding low-light performance, with good color and surprisingly low noise.
While primarily a consumer-oriented digicam, the Optio 555 offers a full manual exposure mode, with exposure times as long as 15 seconds. Throw in the adjustable ISO setting, and the Optio 555 is a capable camera when shooting in low lighting. In my testing, the Optio 555 produced clear, bright, usable images down to the 1/16 foot-candle (0.67 lux) limit of my test, with good color at all four ISO settings (64, 100, 200, and 400). The shot at ISO 64 is a little dark, but still quite usable. The camera's Auto white balance setting did a good job, although some of the ISO 400 shots have a pinkish cast. The camera automatically employs a noise reduction system at slower shutter speeds, which does an excellent job controlling image noise. Even at ISO 400, noise is only moderate, with a very fine grain. The table below shows the best exposure I was able to obtain for each of a range of illumination levels. Images in this table (like all sample photos) are untouched, exactly as they came from the camera.
Flash Range Test
A bright flash with good intensity to 14 feet.
In my testing, the Optio 555's flash illuminated the test target all the way out to 14 feet, with very little decrease in intensity. Flash power was brightest at the middle distances (oddly a little dim at the eight foot distance), but still very good at the 14 foot point. Below is the flash range series, with distances from eight to 14 feet from the target.
Very high resolution, 1,250 lines of "strong detail." Less than average barrel distortion, higher than average pincushion though.
The Optio 555 performed very well on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 800 - 1,000 lines per picture height, in both horizontal and vertical directions. I found "strong detail" out to at least 1,250 lines. "Extinction" of the target patterns didn't occur until about 1,500 lines.
Geometric distortion on the Optio 555 is lower than average at the wide-angle end, where I measured an approximate 0.4 percent barrel distortion. The telephoto end fared somewhat worse though, as I measured 0.6 percent pincushion distortion there. While the barrel distortion is quite a bit lower than average, pincushion is a good bit higher. - Overall, the geometric distortion averages out to being roughly typical. Chromatic aberration was virtually nonexistent, as I couldn't find even one full pixel of 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.) The only other distortion I noticed was some corner softness in the macro shot, in all four corners of the frame, but other images captured at normal shooting distances were exceptionally sharp from corner to corner. Overall, the lens on the 555 is of unusually high quality.
Resolution Series, Wide Angle
Resolution Test, Telephoto
Viewfinder Accuracy/Flash Uniformity
A tight optical viewfinder, but more accurate LCD monitor.
The Optio 555's optical viewfinder was somewhat tight, showing only 83 percent of the final frame at both wide angle and telephoto zoom settings. The LCD monitor fared better, showing approximately 95 percent frame accuracy at both zoom settings. Given that I like LCD monitors to be as close to 100 percent accuracy as possible though, the Optio 555's LCD monitor has a little room for improvement, but is certainly accurate enough for most subjects. Flash distribution was uneven and splotchy at wide angle, with falloff at the corners and edges of the frame. At telephoto, flash distribution was much more uniform, but the camera underexposed the image slightly.
O555 Sample Pictures
O555 "Picky Details"
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