Casio Exilim EX-V7 Review
The EX-V7 has fairly comprehensive white balance controls, with six presets (daylight, overcast, shade, two fluorescent settings, tungsten) and one manual (custom) setting in addition to the default Auto mode. In our tests outdoor white balance was excellent, very difficult to fool. Indoors the results below pretty much reflect our real-world findings; acceptable if you don't mind a color cast when shooting under artificial light, but if you want a more neutral result you're better off using the manual option.
|Auto White Balance||Fluo Preset||Auto White Balance||Incandescent preset|
|Fluorescent light - Auto white balance average,
Preset white balance excellent
|Incandescent light - Auto white balance average,
Preset white balance average.
If you're looking to get really close this probably isn't the camera for you. As is common to most compact digital cameras the EX-V7's macro mode is most effective at the wide end of the zoom, where you can get as close as 10cm, capturing an area just over 9cm across. At the long end of the zoom the performance isn't that different - 40cm subject distance capturing an area just over 11cm wide. There is inevitably some distortion and corner softness when shooting very close up at the wide end, but it is not too strong, and certainly on a par with the better cameras in this class.
Although measurable resolution is hardly likely to be the first thing on the mind of the average EX-V7 buyer it is worth noting that, for a 7MP camera it's a little on the low side. To be more precise the extinction resolution is considerably lower than average as there is a distinct cut off (caused, we presume, by the noise reduction processing) - absolute resolution is pretty normal. The images don't look very clean but it's nice to see that the default sharpening level isn't too high, and that the lens - in the center at least - is actually very capable. It's worth noting that using the smaller aperture setting produces a pronounced loss of resolution, but does avoid the sharp cut-off (mainly because the amount of detail captured is above the frequency threshold at which the noise reduction really takes its toll). To see the same chart at F5.7 click here.
|Click here for the full resolution test chart (at widest aperture).||
resolution 1400 LPH
resolution 1375 LPH
Distortion and other image quality issues
The EX-V7 exhibits moderate distortion at the wide end of the zoom - 1.3% barrel distortion (click here for test chart) - very slightly higher than normal, but not a major issue. The problems really start once you start to zoom towards the telephoto settings, where strong (up to 1.5%) pincushion distortion affects most of the longer part of range to some degree. It plays havoc with remotely square, but is less obvious in more general scenes (click here for test chart). In both these charts you can see fairly obvious corner softness and vignetting issues (see below).
Although the EX-V7 is never going to win any awards for image quality the typical user isn't going to find too much to complain about for standard viewing sizes (either on screen on in print) as long as they don't push it too hard, and you take more shots at the wide end of the lens than the long end.
On the plus side exposures are generally excellent, with only the very occasional overexposure in very bright contrasty scenes marring an almost perfect scorecard. This is important for a camera like this, which will we suspect be used mostly in 'point and shoot' auto-only mode. Color is also generally excellent, just vivid enough to produce crowd-pleasing prints without the need for post processing, but natural enough to avoid burning the retinas of fussier photo enthusiasts. The comprehensive in-camera image options also mean that if you're not happy with the default settings there's more control than usual over the end result.
Focus is fast, but we found that - like most such systems - the multi AF mode often resulted in the camera focusing on the wrong part of the scene, particularly at the long end of the zoom. This, combined with the woefully inadequate stabilization system means that the EX-V7 produces too many blurry pictures at longer focal lengths than it should. We soon switched to the center focus option (the tracking focus option is neat; once the focus point is locked it follows the subject around the frame; but it's far from foolproof). Low light focus isn't brilliant (in fact low light performance in general isn't great).
If you look closely at the images with a critical eye it's easy to find problems, not least of which is an overall lack of biting sharpness anywhere in the frame, but particularly at longer focal lengths and when the aperture isn't wide open. You'll also find mild blue fringing at the edge of very bright areas (and a touch of visible chromatic aberration at the wide end), mild vignetting (corner shading), corner softness, highlight clipping and the aforementioned pincushion distortion.
Important note: The EX-V7 only allows you to set ISO 50-800 manually (ISO 1600 is available in a couple of Best Shot scene modes) and so our standard lab tests do not all include ISO 1600. As you can see a little further down the page, the ISO 1600 setting is incredibly noisy, and of limited use. To see our standard studio comparison shot at ISO 1600 (with the lights turned off) click here.
With tiny, high pixel count chips noise is always going to be an issue, and to a large degree this is more a test of the effectiveness (both measurable and visible) of a camera's noise reduction system. Designers have to balance the desire to produce smooth, clean results with the need to retain as much detail as possible (if you blur away the noise, you blur away image detail too). The EX-V7 shows little visible noise at all at ISO 64-200 (it's measurably low too), and ISO 400 and 800 - though very soft - have very little color noise at all (there is plenty of visible luminance noise, but this isn't the end of the world). That's obvious from the crops here is that the lack of noise comes thanks to strong noise reduction.
|ISO 64||ISO 100||ISO 200||ISO 400||ISO 800|
Noise graph (ISO 100-800)
Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity is on the vertical axis.
Low contrast detail
What the crops and graph above don't show is the effect of noise reduction on low contrast fine detail such as hair, fur or foliage. An inevitable side effect of noise removal is that this kind of detail is also blurred or smeared, resulting in a loss of 'texture'. The crops below show the effect of the noise reduction on such texture (hair) as you move up the ISO range.
|ISO 64||ISO 100||ISO 200|
|ISO 400||ISO 800||ISO 1600 (Hi Sens mode)|
Even at ISO 64 and (particularly) ISO 100 you're losing the finest detail to noise reduction smudging, but not so as you'd worry about. ISO 200-800 see the amount of detail lost - and the amount of visible noise - rising steadily, but the results are useable as long as you're not looking to magnify too much. ISO 1600 is, basically, pointless.
|Louvre Museum pyramid by Didier Quan|
|Oka Frozen Leaf 2002 DP by MarioSS|
from The Dead Leaves of Winter