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Flash Performance

The QV-4000's flash consistently underexposed shots. Luckily the camera does offer the option to select a 'Strong' flash intensity, at this level flash shots were more acceptable (but still not particularly well metered). Whether this was a problem with the cameras flash sensor or just a software bug is unclear. As you can see by the set of skin tone examples below colour balance was not an issue, but exposure was.

Flash Intensity - Weak Flash Intensity - Normal Flash Intensity - Strong
 
With the flash set to 'Strong' the QV-4000 did a relatively good job of covering the entire wall without drop-off at the edges.
(Flash Intensity - Strong)
Color patch test: Good white balance, no colour cast or hue shift, although still a little underexposed.
(Flash Intensity - Strong)
 


Night exposures

The QV-4000 is quite unusual in providing a wide range of timed 'long exposures' all the way up 60 seconds in length. The manual notes that for exposures longer than 1 second the camera will automatically take a second 'dark frame' (lasting equally as long) which will be used to subtract noise from the image. The QV-4000's night exposure ability is impressive and produced some very nice shots (the 'dotted' pattern on the second crop are actually lights from an aircraft).

15 sec, F4.0
30 sec, F4.0


Barrel and Pincushion Distortion

Just like other digital cameras utilizing this (Canon) lens the QV-4000 exhibited approximately 1% barrel distortion at wide angle and an almost unnoticeable 0.4% at full telephoto.

Barrel Distortion, 0.9% @ wide angle Pincushion Distortion, 0.4% @ telephoto


Purple Fringing (Chromatic Aberrations)

I'm glad to report that the QV-4000, although exhibiting some chromatic aberrations, does not 'suffer' particularly badly. Indeed a quick glance at our standard chromatic aberration test shot will tell you that the QV-4000 does better than most 3 megapixel and quite a few of its 4 megapixel peers. How Casio are achieving this (whether it's a side-effect of their built-in noise reduction) doesn't really matter, Kudos to them for a clearly better result.

Hard pressed to find evidence of chromatic aberrations in "every day" shots
Our now standard chromatic aberration test shot


Overall Image Quality / Specific Issues

Overall the QV-4000 produced well exposed, well balanced and colourful images. Resolution was good (although not the best 4 megapixel) and the camera's ability to use the sharpness of the lens was visible in most shots. I was very happy with the QV-3000's image quality when I reviewed it (last year), the QV-4000 doesn't spoil the family reputation, it goes on with a good overall balance to produce pleasing, clean, usable 4 megapixel images. There were (as always) however a few niggles, detailed below:

Aggressive 'flat area' noise reduction

All high megapixel consumer digital camera manufacturers are faced with a quandary, detail and noise or potential loss of detail and smooth images? This comes down to the fact that the CCD's used in these cameras tend to natively generate a certain amount of noise. The amount and visibility of this noise in the final image is defined by a multitude of factors including the quality of the CCD, ISO sensitivity, exposure time, amplifier, image processing circuits and image processing algorithms.

One way to eliminate some of this noise (specifically that which is most visible, on 'flat areas' within an image) is to employ a special noise reduction algorithm. These algorithms are typically similar (loose term) to a 'smart blur', that is they look for very slight differences in plain or gradient areas within an image and even out the colour levels of these areas to remove noise. The side effect can be that some captured detail is also smoothed over.

Not all manufacturers choose this route, some work hard to keep the noise low at source, not use noise reduction (or use a very light approach) to maintain maximum detail at the expense of some visible noise.

Casio have gone down the aggressive noise reduction route with the QV-4000 This, on the whole, does produced impressively clean and noise free flat areas. However, it can at times be too aggressive and lead to 'blotchy' or 'water-colour like' patterns where their should be detail. It's also normally quite visible on the boundary to detail.

In the crop below you can see that the QV-4000's aggressive noise reduction algorithm has destroyed the detail in the shirt material. It could be argued that this wouldn't be so visible at normal viewing sizes, however I would have preferred it if Casio (and here's a note to all manufacturers) had left the option for such a feature in the hands of the user. There is no option to disable noise reduction.

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