There is no such thing as a free lunch, and lenses as complex as those found in the cameras in this review are typically more prone to distortion, low peripheral sharpness and chromatic aberrations than we'd expect from more typical 3 - 5x optical zoom lenses. As a general rule, the more ambitious the lens, the more optical image quality problems we tend to see in photographs. On the plus side, some optical issues can be mitigated, if not cured completely, in-camera. All of these cameras apply distortion correction to their JPEG images, and most also reduce chromatic aberration and fringing automatically, too.
The best performers in this group are the Canon Powershot SX230IS, the Nikon Coolpix S9100 and the Panasonic Lumix DMC-ZS10. At full zoom, (and assuming camera shake is not a factor), edge to edge sharpness from the Canon is excellent. Fringing and chromatic aberration can be a real problem in images from the SX230 HS though, and Canon does not attempt to reduce it in-camera using processing. The Nikon S9100 gives very good performance too, and maintains good sharpness throughout its impressive zoom range. Unlike Canon, Nikon does reduce chromatic aberration and fringing in-camera, and as a result, images from the S9100 are free from obvious colored fringes around high-contrast areas. The only real downside to the S9100's lens is pronounced barrel distortion at its widest setting of 25mm (equivalent) but this is only apparent in scenes that contain obvious horizontal lines.
The same goes for the Panasonic ZS10 and Sony HX9 - images shot at all focal lengths are sharp and clean from edge artefacts and distortion is well-managed. Looking closely at images from the HX9 it is clear that Sony is 'processing out' chromatic aberration and fringing (as with the Nikon S9100 the faint shadows around some high-contrast edges are a tell-tale sign) but it's what the pictures look like that counts, and this respect the HX9 scores very highly.
Canon SX230 HS
Chromatic aberration can be a real problem in images shot with the SX230 HS, as can distortion. The plus side is that Canon's conservative approach to both CA and distortion correction keeps sharpness high.
The Nikon S9100's lens is excellent, and distortion is extremely well corrected. There is almost no chromatic aberration in images taken with the S9100 either, thanks, at least in part to effective in-camera CA reduction.
Of all the cameras in this group, the ZS10 has one of the best lenses. Distortion is well-controlled at all focal lengths, sharpness is high and uniform, and chromatic aberration is all but absent.
The Pentax is at its best at the wide end of its zoom. This image was taken at 280mm (equivalent) and demonstrates the general haziness which mars images taken at the long end of the RZ10's 10x zoom.
Central sharpness from the Samsung WB210's 10x zoom is high at all settings but at wide focal lengths (<50mm) very obvious corner softness (at least partly due to in-camera distortion correction) reduces image quality significantly.
Along with the Panasonic ZS10, the Sony HX9 sits at the top of this group in terms of optical quality. Sharpness is high, and almost uniform across the frame at all focal lengths, distortion is well-controlled and chromatic aberration is undetectable. Naturally, this excellent performance can partially be attributed to effective in-camera processing.
The weakest performers in terms of optical quality are the Pentax RZ10 and Samsung WB210. Images from the Pentax RZ10 lack 'true' sharpness at all focal lengths (partially made up for by aggressive in-camera sharpening), but matters get worse towards the long end of its 10x zoom lens, and towards the corners at the wide end. Compared to the joint-winner of last year's group test, the Samsung HZ35W, the WB210 displays more noticeable corner softness as well as purple fringing. Interestingly, in its 21mm equiv. 'Super Wide Shot' mode, the WB210 gives decent sharpness (except at the corners) and only a marginal increase in barrel distortion. As such, this mode is eminently usable for all but the most critical of scenes.
Best of the bunch: Panasonic ZS10, Sony HX9
Middle of the road: Canon SX230 HS, Nikon S9100
Bottom of the class: Pentax RZ10, Samsung WB210
Noise / noise reduction
Noise is a fact of life in digital images, and its effects can have a significant impact on the final pixel-level image quality of your photos. Sometimes though, it is the effects of noise reduction that have the most impact upon image quality. Each camera manufacturer approaches this problem in a different way, some are aggressive in their reduction of luminance noise, creating images with less noise but also less detail. Others attack chroma (color) noise more aggressively, which tends to keep detail capture reasonably high but can result in images that look a little murky and lacking in saturation.
How well these models cope with noise is a key differentiator when it comes to absolute image quality. We've picked representative 'real world' examples to show you here - for an idea of how well these cameras compared in a controlled environment, take a look at our studio comparisons page.
Canon SX230 HS(ISO 3200)
The Canon SX230 HS is perhaps the best performer in this group when it comes to managing noise - an ability that is especially evident at high ISO settings. Images taken towards the upper end of its ISO range lack crispness when compared to those taken at or close to base ISO, but as you can see from this shot (taken at ISO 3200), high-contrast detail is well-preserved and midtones are relatively smooth.
Nikon Coolpix S9100 (ISO 640)
The Nikon Coolpix S9100 gives better performance at high ISOs than its predecessor, but lags towards the bottom of this group of cameras overall. As we'd expect from Nikon, the S9100 tackles chroma (color) noise quite aggressively, which can lead to colors looking rather desaturated at medium to high ISO settings, but at low ISO settings, the S9100's relatively cautious approach to luminance noise (and the correspondingly restrained smoothing applied to images) means that images shot in high-contrast conditions are impressively sharp and detailed.
Panasonic Lumix DMC-ZS10 (ISO 100)
The Panasonic ZS10 has something of a split personality as far as noise is concerned. Most of the time, in bright, high-contrast conditions it is pretty hard to spot any problems at all. However, take a look at low-contrast areas, like the water in this scene, and it is obvious that even at the lower end of its ISO scale noise and noise-reduction are reducing detail. Towards the upper end of its ISO sensitivity scale noise levels rise rapidly and the effects of noise reduction become very destructive. At its maximum ISO 1600, the ZS10 gives amongst the worst critical image quality of the cameras in this group.
Pentax Optio RZ10 (ISO 1600)
Images from the Pentax Optio RZ10 are amongst the nosiest we've seen from the cameras in this group. Even at its base ISO sensitivity of 80, luminance and chroma noise are very obvious, although super-aggressive sharpening keeps the impression of detail quite high. Beyond ISO 400, images become rather 'hazy' as noise reduction really kicks in until at the upper end of its ISO scale low contrast detail is just a mush, and the RZ10 can only really resolve very high-contrast scene elements, like the writing on this road sign.
Samsung WB210 (ISO 800)
At its base ISO setting of 80, the Samsung WB210 is capable of resolving a lot of detail, and in bright, high-contrast conditions it gives some of the most pleasing images of any camera in this group. Noise really starts to be a problem higher up the ISO scale though and in the image above it is clear that by ISO 800, noise reduction is blurring fine detail and introducing a characteristic haziness across the entire image. By ISO 1600 pictures from the WB210 are very smudgy and only high-contrast detail is accurately described.
Sony Cyber-shot HX9 (ISO 400)
Sony's approach to noise reduction in the HX9 is to aggressively reduce luminance noise, which gives images taken at medium to high ISO settings a rather odd, plastic appearance when viewed at 100%. Even at ISO 400, as you can see from this photograph, fine detail looks almost as if it is melting, although high-contrast edges remain reasonably sharp which masks the problem in small prints and when images are viewed full-screen.
Best of the bunch: Canon SX230,
Middle of the road: Samsung WB210, Sony HX9, Nikon S9100