Friday, January 26, 2007

Canon IXUS 850IS

On its introduction last September at Photokina, the Canon IXUS 850IS followed the IXUS lineage; a very nicely made and nicely designed ultra-compact stainless steel bodied compact digital camera. Some signature features of the new camera include another million pixels over the 800IS, its predecessor and, a new, 28-105mm (35mm equiv.) optical zoom lens that provides a much more versatile focal range (for almost any subject) than that of its predecessor’s 35-140mm lens.

In terms of the lens' brightness, it has a fast F2.8 maximum aperture at 28mm end of the zoom that is joined by a very modest F5.6 maximum aperture at full zoom. However, Canon has cannily included optical image stabilisation to help in lower lighting or at longer focal lengths where you don’t want the flash to fire; it works really well having three settings: continuous, panning and shot only. As you have guessed, the first mode is on all the time, panning works well with horizontally panned snaps and the final shot mode activates when the image is made. Of the three, the latter works best for most subjects.

Enhanced (over the 800IS) sensitivities run from ISO 80 to ISO 1600, but in truth, sensitivities above ISO 400 are noisy and at ISO 800 and 1600, almost unusable. The result – unless having an image is more important than its absolute quality – is images that can only really be used at smaller print sizes.

Another problem on the 850IS is the noise reduction processing, which is much more aggressive on this camera than on previous IXUS’. The processing is via Canon’s DIGIC III processor, the latest iteration of that Canon technology, but because the small 1/2.5-inch has just over 7-megapixels crammed onto it, noise issues are actually worse on this model than other IXUS’ I’ve looked at.

The result of the noise reduction processing is loss of fine detail in all shots taken over ISO 200, elements such as fur, hair, or foliage in landscape shots for example, are smoothed over and, the result is an image that appears to contain tiny blobs of homogenized colour where once there was detail. I will look at image quality in more detail later.

In the meantime, in terms of handling, the 850IS is very nice to use. The large 2.5-inch screen is bright, has a wide angle of view and provides a very clear and clean display, though bright point sources of light made it flare badly. Menus are of the “usual” Canon type with tabbed pages of colour-coded options all scrolled using a ubiquitous four-way jog dial that is also used to scroll images in playback.

The screen can be switched off and you can adjust the level of information displayed also display, this includes a composition grid and, in playback, you can get a histogram display as well; on balance I feel this would have been better as a “live” option when shooting.

The shutter release is surrounded by a neat rocker-style lens zoom control and joined on the top plate with an attractive-looking illuminated on/off button. Despite the small size of the camera, it boasts a small optical viewfinder that is okay to use but is very slightly blurry at all focal lengths. To its right is a flip round mode dial to select manual and auto shooting modes, the Scene selection that provides access to 17-subject program modes (including aquarium modes and the usual array of night scene, portrait and landscape settings) and finally an excellent video mode that provides 640 x 480-pixel clips at 30fps with audio.

Other kit includes Face Detection AF/AE focus control that while a bit of a novelty seems to work quite well. However, the camera’s advanced Artificial intelligent Auto Focus (AiAF) system seems hit and miss, picking seemingly random elements to focus upon even when refocusing on the same scene without moving the camera or viewpoint.

Images are stored on SD/MMC external storage that slots in a port on the base of the camera alongside the Nb-5L lithium-ion battery pack. This holds enough of a charge for around 260-shots but in practice, I found it is less if the image stabilisation is set to continuous and you do a lot of work with the flash.

Metering and exposure control are very reliable although I noticed highlight detail is clipped away in hi-key shots loosing detail in image elements such as clouds and almost any highlight area in a scene. Another factor for image quality is the aforementioned image noise, which as with most cameras with an overdose of pixels on a small sensor, is far worse on the 850IS than its predecessor.

Anything over ISO 400 and the noise becomes noticeable, above 800 and it is intrusive. For small enprint size 6 x 4-inch prints this is probably not a major issue but the noise would be very apparent on larger prints and coupled with the detail smoothing from noise reduction processing discussed earlier, it will be come a real issue for prints over 5 x 7-inches.

However, the extra flexibility the wider zoom lens provides more than makes up for some other slight image quality niggles: slight softness at the edges of images (a drawback of the lenses wider 28mm wide angle design) and modest image distortion also at the wide-angle end of the zoom. Lastly, there is a slight softness to images straight out of the camera (sharpening is tad conservative by default) but easily controlled or improved to on PC in image editing software or in the camera.

Colour capture is excellent and because you have plenty of control over colour, sharpness and contrast via the excellent “Func”-tion menu system common to Canon digital compact you can really tweak the output to how you’d prefer. White balance control has the usual presets and an easy to use custom mode; the only slight chink here was in auto mode with mixed lighting indoors where things had a distinct orange cast.