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Olympus C-720 Ultra Zoom

Olympus packs an 8x zoom lens into an amazingly small body, for an amazingly low price.

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C720 Sample Images

Review First Posted: 7/1/2002

Digital Cameras - Olympus C-720 Ultra Zoom Test Images

(Original test posting: 7/1/02)

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:

Good color overall, but high contrast and somewhat dark midtones.

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 The C-720 did fairly well, but had rather high contrast. Adjusting the contrast to the "low" setting helped quite a bit, keeping highlights in check while increasing midtone detail, but I'd still like to have seen brighter midtones at exposure levels that kept the highlights in check. (See the contrast series below.) The shot at right was taken with a +0.3 EV exposure compensation adjustment, which still produces slightly dark midtones (a shot at +0.7 EV seemed way too bright). I chose the Auto white balance setting as the most accurate, though the Daylight setting produced nearly identical results. Skin tones look pretty good, but the blue flowers have a bit of a purplish tinge (a common problem with this shot). Resolution is high, with strong detail in the flower bouquet as well as in Marti's features, though details look a little soft. Shadow detail is also good, with moderate image noise.

To view the entire exposure series from zero to +0.7 EV, see files C72OUTLCAP0.HTM through C72OUTLCAP2.HTM on the thumbnail index page.

Contrast Series:

Low Contrast
Normal Contrast
High Contrast

 

 

Closer Portrait:

Higher resolution, though again slightly dark midtones and high contrast.

Overall results are similar to the wider shot above, and the C-720's long zoom lens helps prevent distortion of Marti's features. The camera's high contrast again gives it a hard time coping with the harsh lighting here, even with its contrast option set to "low." Resolution is much higher here, with great detail in Marti's face and hair. Details are much sharper in this shot, with better definition than in the wider portrait above. Shadow detail is moderate, with low noise. The main shot was taken with a -0.3 EV exposure compensation adjustment. Here's a sample image at the +0.0 EV exposure setting, which is a touch too bright.

 

 

Indoor Portrait, Flash:

Normal Flash +1.7 EV
Slow-Sync Flash +0.0 EV

Plenty of flash power and even illumination, but a lot of exposure boost needed. Also a slight orange cast from the room lighting.

With the help of a +1.7 EV exposure compensation adjustment, the C-720's flash illuminated the subject well, with good intensity. The default exposure setting badly underexposed the shot, with weak flash intensity and slight bluish tints in the shadows of the Marti's shirt. There's also an orange color cast from the strong incandescent lighting in the room, which dissipated slightly with the brighter exposure. Color on Marti and the flower bouquet looks pretty good, though some orange tints appear in the shadows on her face and in her hair. I also shot with the Slow-Sync flash mode, which resulted in more even lighting from the longer exposure. However, flash power was again low, and the overall exposure very dim with a yellow cast.

 

 

Indoor Portrait, No Flash:

Auto White Balance
Incandescent White Balance
Slightly warm color balance and high contrast.

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 C-720 performed fairly well here, though both the Auto and Incandescent white balance settings produced warm casts. The Auto setting resulted in the warmest image, so I chose the Incandescent setting as the most accurate. I chose an exposure adjustment of +1.0 EV, but found the results rather contrasty. The C-720's Low Contrast setting corrected this problem, but increased the yellow cast slightly. Skin tones are warm from the color cast, and the blue flowers are dark and purplish (a common problem among digicams with this shot).

To view the entire exposure series from zero to +1.3 EV, see files C72INTP0.HTM through C72INTP4.HTM on the thumbnail index page.

ISO Series:
The C720 has an option for variable ISO, so I shot the series below at each of the three ISO options. Image noise on the C720 is a little odd. It shows the most noise in the blue channel, which is typical for digicams. What's strange though, is that the green channel shows the next most noise, quite a bit more than appears in the red channel. - Usually the green channel is the most noise-free. Overall noise seems a bit higher than average at the ISO 100 setting, increases at ISO 200, and becomes quite pronounced at ISO 400. Increased ISO always brings more noise with it, but the C720 seems to start off with a bit more than usual.

ISO 100
ISO 200
ISO 400

 

 

House Shot:

Auto White Balance
Daylight White Balance

A very slight color cast, but great detail and resolution.

Both the Auto and Daylight white balance settings produced good results on this shot, although, the Daylight setting was just a little warm. The Auto setting also has a slight yellowish cast, but overall color is still good. Resolution is high, and detail is strong in the tree limbs above the roof and in the shrubbery in front of the house. Details are also fairly sharp throughout the frame, though the corners are slightly soft. The fine foliage details in front of the house are very well-defined, apparently helped along somewhat by the in-camera sharpening and the camera's inherently higher contrast.

 
 

 

Far-Field Test

Good dynamic range and excellent detail.

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 C-720 does an excellent job here. The leaf and branch details in the tree limbs above the roof are very well defined, even those that are at a fair distance behind the house. The shrubbery and fine foliage in front of the house also have great detail, with very good definition. There's just the slightest hint of corner softness on both sides, but the rest of the frame is sharp. The camera picks up a lot of detail in the bright white paint around the bay window, though it loses some of the more subtle details. The shadow area above the front door shows strong detail in both the brick pattern and porch light. The Auto white balance setting produces good color, though the greens are a bit yellowish. Overall, a very good performance. The table below shows a our standard resolution and quality series, followed by ISO, Contrast, and Sharpness series.

Resolution Series:

Giant / Fine
Giant / Normal
Large / Fine
 
Medium / Fine
 
Small / Fine
 
Tiny / Fine
 

 

ISO Series:

ISO 100
ISO 200
ISO 400

 

Contrast Series:

Low Contrast
Normal Contrast
High Contrast

 

Sharpness Series:

Low
Normal
High

 
 

 

Lens Zoom Range

Great (!) 8x 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 (8x, in this case), and at full telephoto with the digital zoom enabled. The C-720's lens is equivalent to a 40-320mm zoom on a 35mm camera, really reaching out there for distant details. Following are the results at each zoom setting.

Wide Angle

 

8x Telephoto
3x Digital Telephoto

 

 
 

 

Musicians Poster

Auto White Balance
Daylight White Balance

Slightly cool color balance, but good detail.

This shot is frequently a tough test for digicams, as the abundance of blue in the composition usually tricks white balance systems into producing a warm color balance. As it happens though, the C720 went a bit the other way, producing a pale, slightly bluish image with the Auto white balance setting. Alternatively, the Daylight white balance produced a warmer tones, with a bit of a reddish tint in the blue background. Despite the red tint in the background, skin tones look more natural with the Daylight white balance. The blue robe came out a bit greenish from the warm cast, but still nearly accurate. Only faint purple tints exist in the robe's deep shadows, a common problem with this shot as this blue is difficult for many digicams to interpret. The embroidery of the blue robe has strong, well-defined details, and resolution appears high throughout the frame.

 

 

Macro Shot

Standard Macro Shot
Macro with Flash
About average macro performance, but good resolution and detail.

The C-720 performed about average in the macro category, capturing a slightly large minimum area of 3.93 x 2.95 inches (100 x 75 millimeters). Resolution is very high, with sharp, well-defined details in the dollar bill, coins, and brooch. Exposure is just a little bright, and overall color with the Auto white balance is a little warm. The wide-angle lens position also results in quite a bit of barrel distortion. (There's also a little corner softness.) The C-720's flash had trouble throttling down for the macro area, overexposing the shot. The long lens also casts a shadow from the flashes light in the lower left corner.

 

"Davebox" Test Target

Auto White Balance
Daylight White Balance

Slightly warm color balance, but good exposure.

Both the Auto and Daylight white balance settings produced slightly warm images, though the Daylight setting had the stronger cast. Exposure looks good, although contrast is a little high (noticeable by the small loss of detail in the shadows and highlights). That said, the C-720 picks up the subtle tonal variations of the Q60 target well, up to the "B" range. Color saturation is pretty good, as is color accuracy apart from the slight warm cast. The deep shadows seem to be where the C720 had the hardest time, as the shadow area of the charcoal briquettes shows only weak detail, with a moderate noise level. (The noise "grain pattern" is also rather large, making it more evident than might otherwise be the case.)

 

 

Low-Light Tests

Good exposures at light levels well below typical city street lighting.

With full manual exposure control and a maximum shutter time of eight seconds, the C-720 does pretty well in the low-light category. At ISO 100, the camera captured bright, clear images at light levels as low as 1/4 foot-candle (2.7 lux), though the target remained visible as low as 1/16 foot-candle (0.67 lux). At ISO 200, images were usable as low as1/8 foot-candle (1.3 lux), and as low as 1/16 foot-candle at ISO 400. The camera's Noise Reduction system did a fairly good job of eliminating image noise, however, a few bright pixels of noise made it into all of the images (with the highest level at ISO 400). Typical city street lighting equates to about one foot-candle (11 lux), so the C-720 ought to do a good job with much darker shots. The Auto white balance setting produced good color, though was slightly warm at the dimmer exposures. 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.

  1fc
11lux
1/2fc
5.5lux
1/4fc
2.7lux
1/8fc
1.31lux
1/16fc
0.67lux
ISO
100
Click to see C72LL103.JPG

2 secs
F2.8

Click to see C72LL104.JPG

5 secs
F2.8

Click to see C72LL105.JPG

8 secs
F2.8

Click to see C72LL106.JPG

8 secs
F2.8

Click to see C72LL107.JPG

8 secs
F2.8

ISO
200
Click to see C72LL203.JPG

1.3 secs
F2.8

Click to see C72LL204.JPG

2.5 secs
F2.8

Click to see C72LL205.JPG

6 secs
F2.8

Click to see C72LL206.JPG

8 secs
F2.8

Click to see C72LL207.JPG

8 secs
F2.8

ISO
400
Click to see C72LL403.JPG

1/ 2 secs
F2.8

Click to see C72LL404.JPG

1.3 secs
F2.8

Click to see C72LL405.JPG

3 secs
F2.8

Click to see C72LL406.JPG

5 secs
F2.8

Click to see C72LL407.JPG

8 secs
F2.8

 

 

Flash Range Test

Good intensity all the way to 14 feet.

The C-720's flash remained bright all the way to 14 feet from the test target, though it decreased in intensity slightly at the greater distances. Flash power was brightest from eight to 10 feet, and decreased incrementally from there, so I'd rate it as having a range of about 10 feet. Below is our flash range series, with distances from eight to 14 feet from the target.

8ft. 9ft. 10ft. 11ft. 12ft. 13ft. 14ft.
Click to see C72FL08.JPG

1/100 secs
F4

Click to see C72FL09.JPG

1/100 secs
F4

Click to see C72FL10.JPG

1/100 secs
F4

Click to see C72FL11.JPG

1/125 secs
F4

Click to see C72FL12.JPG

1/125 secs
F4

Click to see C72FL13.JPG

1/160 secs
F4

Click to see C72FL14.JPG

1/160 secs
F4

 

 

ISO-12233 (WG-18) Resolution Test

Great performance, with strong detail to 1,000 lines/picture height.

The C-720 performed 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, but I found "strong detail" out to at least 1,000 lines. "Extinction" of the target patterns occurred at about 1,300 lines.

Optical distortion on the C-720 is lower than average at the wide-angle end, where I measured a 0.54 percent barrel distortion. The telephoto end fared much better, as I could only find about one pixel of barrel distortion. This is a surprisingly good performance for such a long-ratio zoom lens. Chromatic aberration is moderate, showing fairly light coloration on either side of the target lines in the corners. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.) There's quite a bit of blurring in the extreme corners though, particularly at the telephoto zoom setting. Fortunately, this softness doesn't extend very far into the image area.

Resolution Series, Wide Angle

Giant / Fine
Giant / Normal
Large / Fine
 
Medium / Fine
 
Small / Fine
 
Tiny / Fine
 

 

Telephoto

Large / Fine

 

 

Viewfinder Accuracy/Flash Uniformity

Very accurate EVF.

The C-720's electronic viewfinder (EVF) is very accurate at both wide angle and telephoto lens settings. At wide angle, I measured an approximate 99 percent frame accuracy. At telephoto, the viewfinder was very slightly loose, but very close to 100 percent frame accuracy. (Frankly, the coverage was probably exactly 100% for both zoom settings, the minor differences reflecting the margin of error in my measurements.) Given that I generally prefer LCD monitors to be as close to 100 percent accuracy as possible, the C-720 does an excellent job here. Flash illumination at wide angle is bright and even, with only slight falloff at the corners and edges of the frame. At telephoto, flash distribution is also very even. 


Wide Angle

Telephoto

 

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