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White Balance

Aside from the default auto setting there are six white balance presets (tungsten, fluorescent 1,2 and 3, overcast and sunlight) and a custom (manual) mode, plus an unusual white balance 'fine tune'. The auto white balance (AWB) system did a perfectly good job in daylight but struggled under any form of artificial light, producing a strong color cast. As with previous models in this range we did find that the custom white balance (even using a gray card) was prone to producing images with a slight color cast, making this a very frustrating camera to use in the studio or under any unusual lighting condition. We also found that the custom WB was prone to 'drift', so even if you got it right minor changes in exposure or ISO setting changed the color. This simply isn't good enough.

Fluorescent - Auto WB
Red 5.8%, Blue -17.9%
Poor

Incandescent - Auto WB
Red 17.9%, Blue -30.2%
Very Poor
Fluorescent - Preset WB
Red 7.2%, Blue -12.2%
Average
Incandescent - Preset WB
Red 4.4%, Blue -9.1%,
Average

Flash Performance

The SP-550UZ's built in flash gives little cause for complaint; it's powerful enough for everyday use and works well at short distances without blowing out highlights. The recycling time is a bit sluggish (stretching to seven seconds or more if it's firing at full power), but the anti-red-eye system works well (there's also an option to remove red-eye from saved images in playback mode) and exposures are generally excellent. There's a slight warm tone to flash shots, but if your subjects are mainly people this is no bad thing.

Skin tone
Slight warm tone, good exposure
Color chart
Slight warm tone, good exposure

Macro Focus

The SP-550UZ has two macro modes; standard macro and 'super macro'. The normal macro mode is nothing special, getting you as close as 10cm (W) / 120cm (T). At the wide end this allows you to capture an area just over 8.6cm across (with a fair bit of distortion, fairly strong chromatic aberration and noticeably soft corners). At the tele (504mm equiv.) end of the zoom the performance is a little more impressive, capturing roughly the same area from a much greater distance. Unfortunately there's almost as much distortion, and the corner softness is very noticeable.

The Super Macro mode fixes the zoom position at around 60mm equiv., but lets you get a lot closer (1cm), capturing an area around 2.8cm (1.1 inch) across with remarkably little distortion. How useful this is, of course, is debatable; the field of view is very wide, and it's difficult to fill the frame with anything meaningful when shooting from 1cm.

Wide macro -
86 x 64 mm coverage
36 px/mm (905 px/in)
Distortion: High
Corner softness: Fairly high
Equiv. focal length: 28 mm

Tele macro -
86 x 65 mm coverage
35 px/mm (899 px/in)
Distortion: High
Corner softness: High
Equiv. focal length: 504 mm
Super macro mode -
28 x 21 mm coverage
108 px/mm (2751 px/in)
Distortion: Fairly Low
Corner softness: Average
Equiv. focal length: 59 mm

Barrel and Pincushion Distortion

There have obviously been some compromises involved in producing such a compact 18x zoom lens, and nowhere is this more evident than in our distortion tests, which show visible distortion throughout the focal length range. It starts as barrel distortion but fairly quickly turns to pincushion as you zoom in, and we failed to find a single position on the zoom where distortion was near zero. It's not so much the amount of distortion that's a problem (at the extremes of the zoom range it's no worse than most competitors), it's the fact that it occurs throughout the entire range.

It's maybe not something that will significantly mar most 'real world' shots, but you can often see it, and if it bugs you you'll need to use software tools to correct pretty much every picture you take.

Barrel distortion - 1.3% at Wide angle
Equiv. focal length: 28 mm
Pincushion distortion - 0.6%
Equiv. focal length: 75 mm
Pincushion distortion - 0.6%
Equiv. focal length: 168 mm
Pincushion distortion - 0.4% at Telephoto
Equiv. focal length: 504 mm

Specific Image Quality Issues

Overall image quality comments

The word that best describes the SP-550's output in 'real world' use is disappointing. Or perhaps 'patchy'. Looking at the good stuff first, the color (in daylight) is generally excellent; the default settings produce reasonably accurate color that isn't as 'over the top' as some Olympus models we've tried. Exposure is also fairly reliable (there's a slight tendency to overexpose on bright days with a lot of sky in the scene, but this is easily fixed with a touch of negative AE compensation) and the stabilization system works well as long as you keep within a stop or two of the 'reciprocal focal length' recommended minimum shutter speed.

But there are, perhaps inevitably given the ambitious lens range, problems. Looking at the images closely reveals them to lack the biting sharpness needed for larger prints; they are actually pretty soft. Throw in corner softness, fringing, noise reduction smearing of low contrast detail, highlight clipping and focus errors and you've got a camera that challenges you to get a perfect result, rather than helping you. Of course some of these issues are minor, some fairly rare and some are common to all small sensor digital cameras, but the SP-550UZ manages pretty much a full house.

To put the softness issue in to perspective if you're looking to produce standard-sized prints (say 5x7 maximum) you'll probably be perfectly happy with the SP-550's output (with a little sharpening), and by shooting raw you can overcome some of the issues, but only if you're prepared to put some work in. We found many images looked a little 'flat' out of the camera, but they do respond well to a little contrast and saturation tweak.

Focus Errors

Although we're used to 'super zoom' cameras struggling and hunting a little at the long end of the zoom we're less used - and less happy to accept - focus errors where the camera indicates the shot is in focus when it clearly isn't (sometimes it's so far out you can see the preview image is blurred). The problem isn't restricted to the long end of the lens, and appears to be worse in iESP mode, in very dim or very bright light and when using the macro function. Both examples below are clearly out of focus to a greater or lesser extent despite the camera showing them as being in focus when the shutter was half-pressed (the lower example also has obvious chromatic aberrations). I'd estimate that maybe one in 20 shots on our camera had a focus error requiring me to refocus (sometimes over and over again) until the camera finally got it right - and of course if the focus error is fairly small you don't discover it until you've looked at the images on-screen at home, by which time it's too late. This is simply not acceptable.

100% crop 69mm (equiv), F3.6, 1/400 sec
100% crop 504mm (equiv), F5, 1/640 sec

Fringing

The SP-550UZ shows fairly strong purple fringing in some shots at all focal lengths, though it is worst when there are blown out highlights in the frame. It's not terrible, and certainly doesn't blight every shot you take on a bright day, but it is easily visible in some shots even in a small print. We also found some chromatic aberrations (green / red fringes) at wider apertures at the long end of the zoom and in macro mode.

100% crop 480mm (equiv), F4.4, 1/500 sec
100% crop 31mm (equiv), F3.0, 1/60 sec

Exposure / clipping issues

Point the SP-550UZ at any bright scene and the chances are you'll end up with fairly painful clipping of highlights, caused by a combination of limited dynamic range and mild over exposure of very bright scenes. The answer is to use a little negative AE compensation (you can fairly safely leave it set to -0.3 or even -0.7 when out shooting on bright days), but it's not an ideal situation. To be fair the SP-550UZ is hardly any worse than its competitors in this respect.

100% crop 28mm (equiv), F2.8
100% crop 28mm (equiv), F2.8
100% crop 28mm (equiv), F3.5

Image stabilization

This is the first Olympus 'ultra zoom' camera to feature mechanical image stabilization since the now legendary C-2100UZ back in 2000. Where that camera had a moving lens the SP-550UZ has a moving sensor. Unlike some CCD-shift systems the SP-550UZ also stabilizes the preview image (though only after the shutter has been half-pressed, and it doesn't work in the movie mode).

Our experience of CCD-shift systems so far has been somewhat mixed; they invariably work, but rarely as well as the optical (lens-shift) alternative. That said, this one seems to do a pretty good job, certainly giving us a good two stop advantage over non-stabilized shooting (though not, it must be stressed, with 100% reliability).

In our tests around 80% of shots taken at two stops below the recommended minimum shutter speed (using the focal length reciprocal rule) came out sharp, but the effectiveness falls quickly once you push it any further, particularly at longer focal lengths. It's not quite as good as the optical image stabilization used by Panasonic etc, but is undeniably useful and certainly one of the better CCDS-shift systems I've tried.

Real world example: 238mm (equiv), 1/30th Second, hand-held.
Stabilization off Stabilization on

The stabilization test

In this simplified version of our SLR IS test, five hand-held shots were taken of a static scene with the stabilization off and on. The shutter speed was decreased and repeated (from 1/500 sec to 1/50 sec). The zoom was set to its maximum position (504mm equiv.), the test target was 12 m away from the camera. The test was repeated three times and an average taken.

The resulting images were then inspected and given a blur score - 'Sharp' (no visible blurring at 100%), 'Mild Blur' (the kind of camera shake that is tolerable at small print sizes) and 'Heavy Blur' (unusable due to camera shake).

As the charts below show we were able to get a measurable two stop advantage. More importantly we were able to get 'usable' results in two out of three shots at shutter speeds as low as 1/8th second

Hand-held, no stabilization (504mm equiv.)

As you can see from the chart below only at 1/500th sec or above can we be confident of getting sharp results from the majority of shots, and once you get to 1/100th sec and below the majority of shots are heavily blurred, and none are sharp.

Hand-held, stabilization on (504mm equiv.)

With stabilization on the results are much better, with the majority of shots appearing sharp down to 1/100th sec. Below this we saw only a minor improvement in the number of 'just usable' shots, and no fully sharp results. Below 1/50th second (4 stops or more) the stabilization system made no measurable difference.

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