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Digital Cameras - Pentax Optio S 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, ISO setting, compression setting, etc. Rather than clutter the page below with *all* that detail, we're posting the Thumber index so only those interested in the information need wade through it!

 

Outdoor Portrait:

A surprisingly good job for a subcompact, with high resolution, and nice color.

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, and the Optio S performed well.

The shot at right was taken with a +0.7 EV exposure compensation adjustment, which brightened the midtones, albeit at the expense of highlight detail. Both the Daylight and Auto white balance settings produced similar results, but I felt the Daylight setting produced the most natural color overall.

Skin tones look very good, would really be hard to improve upon, and while rendered a little dark, the always-difficult blue flowers in the bouquet are pretty much on the money in terms of hue. (This is a very difficult blue for many digicams to get right.) The strong reds and greens look quite good as well, with just the right levels of saturation. Resolution is high, with good detail visible throughout the frame. Shadow detail is slightly limited in the darkest areas, but noise is pretty low. Overall, an excellent performance.

To view the entire exposure series from zero to +1.0 EV, see files OSOUTDP0.HTM through OSOUTDP3.HTM on the thumbnail index page.



 

Closer Portrait:

Excellent resolution, detail, and color.

The Optio S did an excellent job on this closer shot as well. Lots of detail, good color, and generally low noise, with very good shadow detail. Once again, a surprisingly good performance for a subcompact camera. The shot at right was snapped with +0.3 EV of exposure compensation, and the normal contrast setting. I tried the low contrast setting on this shot, figuring that it would mute the harsh highlights a bit, but the result seemed to be just a dulling of the overall image. (It seems to have boosted the shadow and lower midtone brightness more than it held the highlights in check. (Using the low contrast setting with less exposure compensation might have worked well, but as luck would have it, I didn't shoot that particular combination.) My missing the ideal combination of exposure & contrast settings notwithstanding, a very good performance here.



 

Indoor Portrait, Flash:
Normal Flash

Slight underexposure, but evenly -lit. Strong orange color cast from the room lighting.

The Optio S' built-in flash illuminates the subject well based on its fully automatic exposure setting, but the shot is slightly underexposed overall, and the Optio's exposure compensation setting doesn't affect the flash intensity. Still, coverage is even, and a lower-key subject (less white in the frame) would doubtless expose well. The background incandescent lighting results in a strong orange cast on the background wall, as well as on Marti's features.



 

Indoor Portrait, No Flash:
Auto White Balance
Incandescent White Balance
Manual White Balance

Good color with the Manual white balance, though slightly greenish, and some odd highlights.

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 S' Auto white balance setting had quite a bit of trouble here, producing a strong orange-magenta cast. The Incandescent white balance also produced a warm cast, but with more of a sepia tint. The Manual setting resulted in the most accurate color, though overall color is a little greenish. Despite the color tint, Marti's skin tone looks pretty good. Color in the flower bouquet also looks good, though the blue flowers are dark and purplish (a common problem with this shot.) The shots at right have a +1.0 EV exposure compensation adjustment, which results in unusual highlights on Marti's shirt, particularly in the example shot with the Manual white balance option.

ISO Series:
Noise is quite low at the ISO 50 sensitivity setting, increasing to a moderately high level at ISO 200. The exposure also brightens a great deal with the ISO 100 and 200 settings, resulting in strong, greenish highlights.

ISO Series
ISO 50
ISO 100
ISO 200





 

House Shot:
Auto White Balance
Daylight White Balance
Manual White Balance

Moderate resolution but a lot of softness in the corners. Reasonable color all around, best with the Manual setting, though slightly cool.

The Optio S' Manual white balance setting produced the most accurate white value on the house trim in this shot, though the overall color is slightly cool. Alternatively, the Auto and Daylight white balances both produced warm, somewhat yellow images here. Resolution is only moderate in the tree limbs above the roof, though the house and front shrubbery show stronger detail. Details are soft throughout the frame, with increased softness in the top two corners of the frame. Noise is a little high, especially in the grass area.

- The conclusion to draw from this shot is that the Optio S' lens does much better with more distant subjects than closer ones like this poster, shot in the studio at a distance of 4-5 feet.



 

Far-Field Test

Good resolution and detail. Shadow detail is strong, though highlight detail is very limited.

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 S does a good job, typical of a three megapixel digicam. The tree limbs over the roof and fine foliage in front of the house show pretty much exactly the level of detail you'd expect from a three megapixel digicam. - In this more distant shot, the Optio S' lens performs quite well. The bright sunlight tricks the camera into losing most of the detail in the bright white paint surrounding the bay window, a trouble spot for many digicams. Detail is stronger in the shadow area above the front door, however. Overall color is just a little washed out, due to the slight overexposure. The table below shows a standard resolution and quality series, followed by ISO, contrast, saturation, and sharpness series.

Resolution Series:

Wide Angle "Fine"
JPEG
"Normal"
JPEG
"Economy"
JPEG
2,048 x 1,536
OSFARLF
OSFARLN
OSFARLE
1,600 x 1,200
OSFARMF
   
1,024 x 768
OSFARSF
   
640 x 480
OSFARTF
   


ISO Series:

ISO Series
ISO 50
ISO 100
ISO 200

Contrast Series:

Contrast Series

Lowest

Low

Normal

High

Highest

Saturation Series:

Saturation Series

lowest

Low

Normal

High

Highest

Sharpness Series:

Sharpness Series
Lowest
Low
Normal High
Highest




 

Lens Zoom Range

A typical 3x 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 (3x, in this case), and at full telephoto with the digital zoom enabled. The Optio S' lens is equivalent to a 35-105mm zoom on a 35mm camera. That corresponds to an average wide angle to a moderate telephoto. Following are the results at each zoom setting.

Wide Angle
3x Telephoto
4x Digital Telephoto



 

Musicians Poster
Auto White Balance
Daylight White Balance
Manual White Balance

Slightly warm color balance with the Daylight setting, though it proved most accurate overall. Good resolution and detail.

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. The Optio S' Auto white balance setting fell prey to that syndrome, resulted in a very warm cast, while the Manual setting produced a very cool image. Though slightly warm, the Daylight setting produced the most natural color. Skin tones are slightly yellow, and the warm cast gives the blue robe a greenish cast. Resolution is high, with great detail in the embroidery of the blue robe.



 

Macro Shot
Standard Macro Shot
Super Macro
Macro with Flash

Impressive macro performance with Super Macro mode, and flash does well.

The Optio S performed surprisingly well in the macro category, capturing a minimum area of only 2.76 x 2.07 inches (70 x 53 millimeters) in the normal macro mode. In Super Macro mode, the minimum area is only 1.66 x 1.24 inches (42 x 32 millimeters). At the normal macro setting, details are soft throughout the frame, with a lot softness in the corners. However, in Super Macro mode, details are sharper, though corner softness is again visible. Color balance is warm from the Auto white balance setting, and exposure looks good. The camera's flash throttled down for the macro area pretty well, although the brooch reflected the light right back into the lens (not really the camera's fault).

Overall, really a surprisingly strong macro performance for a subcompact digicam. A good choice for photographing very small objects.



 

"Davebox" Test Target
Auto White Balance
Daylight White Balance
Manual White Balance

Minor color casts with each white balance setting, but good color rendition overall.

Though slightly greenish, the Optio S' Manual white balance setting produced the best overall color and white value in the large white color block and mini-resolution target. The Auto and Daylight settings both resulted in very warm images. Exposure looks good, though slightly bright, and the Optio S distinguished the subtle tonal variations of the Q60 target well. Colors are very good in the large color blocks, though a touch undersaturated. That said, the large red and blue additive primary color blocks are actually just a bit oversaturated. The shadow area of the charcoal briquettes shows limited detail, but with low noise. All in all, a very good performance.



 

Low-Light Tests

Stay tuned, I need to re-shoot my low-light tests... (Sorry! :-(



 

Flash Range Test

Slightly low flash intensity, but effective to about 11 feet from the target.

In my testing, the Optio S' flash illuminated the test target all the way out to 14 feet, though with very dim intensity at the furthest distances. Flash power was brightest to about 10 ~ 11 feet from the target. There's some indication though, that the Optio S "cheats" a little with its flash photos - Like several other subcompact cameras I've tested lately, the Optio S seems to be achieving acceptable flash range by boosting its ISO somewhat. The software I use to read EXIF headers (Cameraid and Thumber) isn't able to interpret the Optio's ISO readings in the files, but judging from the noise levels in these flash shots, it seems that the camera is boosting its ISO to 200 when snapping flash shots under dark conditions, and at the same time cranking up the noise-suppression processing. The net result is somewhat greater flash range, but at the cost of higher image noise and reduced detail. Below is the flash range series, with distances from eight to 14 feet from the target.

8 ft 9 ft 10 ft 11 ft 12 ft 13 ft 14 ft
Click to see OSFL08.JPG

1/125 secs
F4.8

Click to see OSFL09.JPG

1/125 secs
F4.8

Click to see OSFL10.JPG

1/100 secs
F4.8

Click to see OSFL11.JPG

1/100 secs
F4.8

Click to see OSFL12.JPG

1/80 secs
F4.8

Click to see OSFL13.JPG

1/40 secs
F4.8

Click to see OSFL14.JPG

1/60 secs
F4.8




 

ISO-12233 (WG-18) Resolution Test

Moderately high resolution, 900-1,000 lines of "strong detail." High barrel distortion.

The Optio S performed fairly well on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 600 lines per picture height in both horizontal and vertical directions. I found "strong detail" out to about 900 lines per picture height vertically, and 1,000 lines horizontally. "Extinction" of the target patterns didn't occur until about 1,150 lines.

Optical distortion on the Optio S is higher than average at the wide-angle end, where I measured an approximate 1.0 percent barrel distortion. (Average is about 0.8%, still much too high, IMHO.) The telephoto end fared much better, as I couldn't find even a single pixel of pincushion or barrel distortion. Chromatic aberration surprisingly low, as there's relatively little color around the target elements. (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.) There's a good bit of softness in the top two corners of the frame, mainly noticeable with the lens at the full wide angle setting. (Although seemingly not as much as I saw with the House poster shot above.)

Resolution Series, Wide Angle
Wide Angle "Fine"
JPEG
"Normal"
JPEG
"Economy"
JPEG
2,048 x 1,536
OSRESWLF
OSRESWLN
OSRESWLE
1,600 x 1,200
OSRESWMF
   
1,024 x 780
OSRESWSF
   
640 x 480
OSRESWTF
   

 

Resolution Test, Telephoto
2,048 x 1,536
(Fine, Tele)
OSRESTLF




 

Viewfinder Accuracy/Flash Uniformity

A very tight optical viewfinder, but nearly dead-accurate LCD monitor.

The Optio S' optical viewfinder is very tight, showing approximately 70 percent frame accuracy at wide angle, and approximately 73 percent at telephoto. The LCD monitor is much more accurate, and actually a hair loose, as the viewfinder shows just a little over 100 percent of the frame. Given that I like LCD monitors to be as close to 100 percent accuracy as possible, the Optio S' LCD monitor is pretty near perfect, but the optical viewfinder definitely needs some work. Flash distribution is slightly uneven at wide angle, with a small amount falloff at the corners and edges of the frame. At telephoto, flash distribution is more even, though dimmer.


Wide Angle, Optical

Telephoto, Optical

Wide Angle, LCD

Telephoto, LCD


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