Before I bought it, I was not happy with the test images I've seen of digital cameras in general. Now that I've had one for a few months, I've used it very intensively. By now I made more than 5,000 pictures with it. In the beginning I shot some 100 pictures a day! I made many that I am quite happy with. It's good for most things except for landscapes, for which 2 megapixels is just not enough, it seems.
The one most important thing that makes it stand out from many others in its price/pixel range is the lens: it has a REALLY GOOD lens. I've seen so many pictures of digital cameras that were all blurry and had colour aberrations and even vignetting in them. Strange but true, the limiting quality factor of many digital cameras is the lens: they seem to have lenses that would hardly have been acceptable in cheap cameras 25 years ago! I've seen none of these problems with the A40.
UPDATE: there is a firmware fix, fixing focusing problems in the 13.4 mm setting.
Problem: Discussion with sample pics of the problem, Discussion of new firmware fix.
Solution: get the fix from: www.powershot.com or www.canon.co.jp.
Obligatory JPG compression. Like many other digital cameras, the camera only outputs JPGs. It is not possible to have pictures that were not reduced by a lossy compression algorithm. Some people hate the idea of having a camera destroy so much information, and wish to have the non-processed data at their disposal. In practice, though, I found it makes little difference. First, one should note that the image from the CCD is already full of artifacts, and some unspecified enhancing filter is already passed over the `raw' CCD information, so you just don't get anything near unprocessed CCD information, and I sort of doubt whether you really want to see what that looks like. Secondly, I did not notice any of the effects of the JPG compression. I think that the signal-to-noise ratio introduced by the compression is better than that of the CCD. The camera has three compression settings (super fine: 5x compression which is really very high quality for a JPG, fine: 8x compression, and normal: 15x compression) with the default being `fine'. I used the `super fine' setting for awhile but eventually I even switched back to `fine' because I saw much noise and many artifacts, but never any JPG artifacts.
Focus. The camera has four focus modes, and I still haven't found out exactly how all of them work. Basically, you have autofocus for very close objects (called macro mode) and autofocus for longer distances (the default mode), and two mystery modes (close and distant) that sort of puzzle me. I've had some problems with the autofocus focusing at very long distances and low light levels (such as an evening skyline). Apparently, it doesn't find anything to focus onto, and defaults to a close focus. I've tried to override the autofocus by means of the `distant' setting but that doesn't quite seem to work. I'm not sure by what mechanism the camera focuses and whether some autofocus is still at work at the `close' and `distant' settings. My solution in this particular case is to use the `distant' mode combined with a high F setting.
Concerning the use of autofocus in low light, I found the following message on photo-forums. I haven't tried this myself though.
DLA - 08:37am Jun 22, 2002 EST (#137 of 182)
[...] I found some useful tips on low light focusing
in another forum:
Basically the camera seems to use a passive AF system which focuses by
detecting the contrast between vertical lines. So, simply focus on an area
within your subject containing vertcal lines and lock the focus, if there are
only horizontal lines, turn your camera 90 degrees to make them vertical.
Using this method I can now get the camera to focus correctly almost every
time in low light.
(see http://www.howstuffworks.com/autofocus1.htm
for more info)
Having now solved my low light focusing problems, I'm very pleased with this
camera (apart from the 13mm focus problem). For features/quality vs price I
don't think this camera can be beaten.
Hope this info helps.
Aperture. The camera has only two apertures, namely f/2.8 - f/4 and f/8 - f/14. The actual F is determined by the length of the lens, and in manual mode, the display shows an approximation of the actual F setting. The diaphragm is selected by a little movable screen that sits in front of the lens, which contains the two holes for the two different F-settings. You can hear the camera click when it moves the screen to adjust its F or closes the lens to read out the CCD. While this system sounds quite minimal, it is just enough for most applications: The f/2.8+ is good for typical scenery pictures or portraits, and the f/8+ is good for close-ups and high depth-of-field pictures taken with a tripod or at very high light levels.
In automatic mode, the camera switches to f/8-14 when the shutter speed is short enough in that mode (about 1/125 th of a second). This already happens when just previewing, and you can hear the camera click and see the screen recalibrate its light level when this happens. This is sometimes cumbersome, because the user interface freezes for a second as the camera switches F setting.
Sensitivity and density. You can set the sensitivity of the camera between 50 ASA and 400 ASA. The camera is probably just amplifying the signal in the higher settings, and noise that is normally invisibly small shows up quite strongly in the 200 and 400 ASA settings, especially in dark areas (this is analogous to a low film density). It's a bit like pushing film, the more you push the lower the density gets. The 100 ASA mode is still good though. Note that things get worse when using tungsten (indoors lamp light) balance, because tungsten light has very bad colour characteristics. It is extremely orange, which means you get very little blue light. Tungsten balance amplifies the blue light by about a factor 3 or 4. This means that, when you have 400 ASA and tungsten balance (a situation you often want in lamp light) the blues are amplified by a factor 20, to more than 1000 ASA! Now, in 50 ASA mode the blues are a little noisy already...
Basically, I treat the camera as a 50-100 ASA camera, and only go higher if absolutely necessary. Note that 50 ASA is not as slow as it sounds, because the cameras has lower resolution that film, and it is less difficult getting a sharp picture. The resolution in pixels is about a third of a mediocre film camera, which means that you can misbehave thrice as badly before you get punished by an unsharp image. For example, shutter times down to about 1/40 second still result in sharp pictures in most situations, as you typically need 1/125 on a film camera. So, actually, the camera is more like a 150 ASA film camera.
User interface pros and cons. There's a lot to say about the user interface of a digital camera. I'm not familiar with other models, so I'm not sure how much better or worse the user interface can be. Ideally, I'd like to have a separate knob for every parameter that has to be set often. Unfortunately, it seems devices such as digital cameras are typically equipped with relatively few buttons, and there's lots of mode switching necessary to reach all necessary functions. I find this a problem on this camera, at least. One has a mode button for switching between F/shutter time, exposure compensation, colour temperature, and effects. The camera reacts rather slowly to a press of the mode button, which increases the chance of being mistaken about the mode it is in. Most parameters are set by the `cursor' buttons (arrow left and arrow right). Since some parameters have a large range, one sometimes has to hold down the buttons long or repress them often. I'd have liked to have something like a thumbwheel instead of the two buttons. It appears one expects the user to use the camera often in the `automatic' mode (selected by the `operation mode' thumbwheel) where most parameters are set to automatic defaults. Still, one gets used to the system quickly. The worst thing is that one cannot change the focus between macro and normal when setting the shutter speed. Worse still, the camera sometimes resets the focus mode back to normal unexpectedly.
The `picture view' mode works smoothly. There is a thumbnail display, and one can easily browse through all the thumbnails with only a few button presses. One can zoom into the pictures deeply, so that one can see if a picture is sharp and not shaken.
A definite pro of the user interface is that the screen shows various important information well. It shows a good approximation of the exposure level of the picture about to be taken, except at low light levels, such as a street by night. Then the display is unfortunately mostly black and one can typically only see light sources. In manual mode, it even temporarily shows what exposure it would have chosen in automatic mode when you are about to take a picture. This way, you can compare your own setting with that of a more or less `normal' setting. The box-shaped markings which show where the light and focus is measured are actually quite useful for getting the objects in the picture properly straight and centered. The different camera settings are optionally displayed in the corners of the screen, and in manual mode the actual F setting is displayed. When one signals that one is about to take a picture by pressing the shoot button lightly, the symbols disappear so one gets a clear view of the picture. All in all, the display is quite effective.
Viewing a composition through the viewfinder and TFT screen. I usually use the screen a lot rather than the viewfinder, but the viewfinder has higher resolution so in practice it's useful to use both. Some people say that the screen is not bright enough to see in bright sunlight, but I have not had this problem. Several people have mentioned problems with the viewfinder though: it is tilted with respect to the actual picture. As I found out, mine is tilted too. The viewfinder's view area is a bit smaller than the actual picture being taken, so in practice I use a combination of both: first I find a composition through the viewfinder, then perfect it using the screen.
Batteries. The camera eats standard AA-type batteries. I have two sets of 1300mAH NiMH rechargable batteries, one in the camera and one in the recharger, so that I always have fresh batteries. The camera drains the batteries very quickly, so non-rechargables are not an option. The batteries typically run out after I've taken about 100-200 pictures, but your mileage may vary according to your shooting habits. They say the screen eats up a lot of power and you can turn it off, but the screen is necessary to tweak the camera so I always have it on. When the low battery indicator appears, you can only take a few more pictures before the camera refuses operation altogether: it closes down and the screen shows `please replace batteries'.