Canon PowerShot Pro90 IS Review
Overall Image Quality
On the whole very good, having the unusual 2.6 megapixels
it's difficult to compare the Pro90 to other 3 megapixel digital cameras
as they will always have the slight resolution advantage. From what we've
ascertained however that advantage is slight and the Pro90 is easily a
match for Sony's excellent F505V from a pure image resolution / sharpness
point of view (more of that on the next pages).
The Pro90 obviously uses almost identical image processing algorithms to the G1 and therefore most images are very "G1 like", that includes the slightly flat or even lack of a solid black on normal images.. I maintain my point on this:
Analysing what's going on here, Canon have deliberately not corrected the black point (or even pushed it up the gray scale) which can give images a "flat" look, but what it in effect does is help to preserve detail in shadows. If you want your images to look more contrasty then all that's required is a simple level correction in Photoshop, or the use of the "high contrast" setting built into the camera. At the end of the day I prefer this to camera systems which attempt to select the black point and end up destroying the bottom end of the gray scale. As I said with the G1 the Pro 90's slightly flatter "lighter" images do appear to print better straight out of the camera as shadow detail isn't turned completely black when printed.
ISO 50 also helps to capture very "smooth" looking images with very little or no noise, though it's worth noting that the Pro90's ISO 100 does seem to be noisier than other digital cameras which don't sport the ISO 50 option (this, again is something we noticed about the G1).
Purple Fringing (Chromatic Aberrations)
As to be expected the Pro90 suffers from chromatic aberrations, though certainly not as bad as some digital cameras. These aberrations are more visible at long zooms where you're pushing the lens to its absolute limits (as we've seen on all compact super zoom digital camera lenses).
|Some visible chromatic aberrations on a very long zoom shot (370 mm equiv.)|
|Our now standard chromatic aberration test shot.|
Barrel and Pincushion Distortion
The Pro90 performs very well, especially for a camera with such a long zoom lens. At full wide there's only 0.7% barrel distortion and at full tele pincushion distortion is so small that it's unmeasurable (as good as zero).
|Barrel Distortion, 0.7% @ Wide Angle||Pincushion Distortion, none @ Full Tele|
We've already heard that the Pro90's lens doesn't produce an image large enough to take advantage of the whole 3.1 megapixels of the sensor, Canon had to mask the sensor down to 2.6 megapixels to produce an acceptable image. In some circumstances it was possible to see very slight corner vignetting from the lens system, this was most visible when we were shooting white test cards which tend to make this effect very clear, vignetting appeared at any focal length.
Disclaimer: I'll stress now that I REALLY had to hunt amongst the 1,000+ real life shots I've taken with the Pro90 to find one which clearly demonstrates vignetting, it's unlikely that vignetting would ever become a problem for your every day shots.
|Corner vignetting in a real life shot,
37 mm equiv, 1.3s, F2.8 (tripod)
|Corner vignetting in this shot of our white test card, 37 mm equiv, 1/30s, F2.8|
Vignetting is defined as: Partial masking, or blocking, of peripheral light rays either by intent, or by accident. The blockage of peripheral light rays in a projection lens is due to a lens barrel that is too long, or to an optical system that is not correctly matched to the limiting aperture of the projection lens.
The Pro90 offers a range of different preset white balances as well as manual preset, a simple task of aiming the camera at a white subject and hitting the * button. It's worth noting the addition of a Flash white balance on the Pro90 which (we hope) will help to produce better white balance when using the flash. Samples below give an impression of the Auto, Preset and Manual white balance performance.
* Typical cloudy, wet, January day in the UK
Night / Long Exposures
Canon's noise reduction system is ALWAYS enabled on the Pro90, I'm not really sure what the logical is behind that as all it seems to do is slow down the processing of normal images, I wish they'd just had it kick in for slow exposures (just like it does on the G1 or EOS-D30).
All images below shot at ISO 50, maximum zoom, self timer, infinity focus, incandescent white balance.
|6 sec, F7.1|
|8 sec, F7.1|
As we'd expect noiseless and relatively sharp images, Canon's noise reduction seems to work very well, it would have been nice to see exposures longer than 8 seconds...
Dynamic range simply defines the range of light the camera is able to capture before it either loses detail in darkness (shadows for example) or blows out a highlight (edges of chromed metals are good examples of this). Most consumer digital cameras only have a 8-bit analog to digital converters, plus their CCD's are not built to have a particularly large dynamic range.
Using our new dynamic
range measurement method we measured the Pro90's dynamic range as
(higher numbers are better except for noise):
Canon Pro90 IS
These results are pretty much what we expected, as good as the G1 at ISO 50 & 100, interestingly better performance at ISO 200 and 400 (probably thanks to the "always on" noise reduction). Very much in line with most 3 megapixel prosumer digital cameras.