Written on 1 May 2008

I own three digital cameras, each of which is at or near the top of its respective class: the Canon Ixus 850 (also called Powershot SD 800 IS), the Panasonic Lumix DMC-FZ18 and the Canon 40D. These are representative of the best that is on offer in the classes of pocket camera, bridge camera and enthusiast SLR (Single Lens Reflex). This article gives a real-life comparison rather than technical information, which is easily available.

These three cameras are aimed at different kinds of photo-takers. Every camera ever made is a compromise of some sort and each of these three has its strengths and weaknesses. This review is not intended to pick the 'best' camera, but to show the pluses and minuses of each. It might help you to decide which sort of camera is best for you. Note that I am not saying that each of these cameras is better than its competitors, only that each is a serious contender in its class.

I bought the Ixus because I wanted a camera I could take with me everywhere. It attaches easily to my belt (or could go in a large pocket) and I often take it with me when I go out of the house. I can then forget about it. So no more, "If only I had my camera with me," regrets. The other reasons for buying it were as a back-up in case of failure or loss of my main camera, to take 640x480 movies, to use as a wide-angle when I don't feel like changing lenses on my SLR, to photograph people unobtrusively, and above all, because everyone else has one. The biggest plus point of the Ixus is that I don't hesitate to whip it out and take a snap, which has allowed me to recover the joy of spontaneous image-creation, whenever and wherever. The Ixus epitomises freedom.

The Panasonic Lumix FZ18 lies midway between the Ixus and the 40D, hence the term "bridge camera". It sports a full range of manual options, covers a whopping 28-504 mm equivalent focal length range, and looks like a small SLR. It is aimed at people who want a more versatile and powerful tool than a pocket camera yet balk at the SLR. I bought the Lumix as a wide-angle to super-telephoto all-in-one that is much lighter, much smaller and less cumbersome than the 40D, with its two lenses. In fact, the Lumix is so light it feels like a plastic shell with nothing inside it. I might take it on trips instead of the SLR.

The 40D is the top-of-the-range amateur offering from Canon. It falls a little short of being a professional camera, but this distinction is not going to worry many people. I bought the 40D to get the most versatile and powerful camera I could, short of going to full-frame (ie same sensor size as 35 mm film). I wanted maximum image quality. The reason I did not choose a full-frame camera (apart from size, weight and price) is that I love to do long telephoto shots. The 70-300 mm zoom I use on the 40D, though heavy, is still portable enough for trips and hikes, and can easily be used hand-held, as it is image stabilised. It gives me a maximum telephoto equivalent of 480 mm, which is terrific. To get that on a full-frame camera I would need a small truck to transport the lens and a trailer for the tripod. I also carry the 18-55 IS (image stabilised) mm kit lens, which is mercifully light. With these two lenses I have macro and wide-angle to extreme telephoto, though somewhat less telephoto than in the Lumix.

All three cameras have decent wide-angle ie 28 mm equivalent. All three have image stabilisation. Prices in 2007: Ixus $430, Lumix $580, 40D about $2650 (with two lenses). 

Thinking about what I want in a camera I came up with four aspects: portability, ease of use, versatility and image quality. There is an additional aspect which is even more important, but less easily definable - the fun factor. I want a camera to be a recreational device rather than a clinical photo-making tool. This is because I take my best shots when I enjoy using the camera.

The 40D is ready for use by the time you remove the lens cap, whereas you have to wait for the other two cameras to extend the lens before you can take a shot. The Lumix has a poor electronic viewfinder that cannot compete with the two Canons. The 40D focuses much faster than the two small cameras. Being so small, the Ixus is not easy to hold. The Lumix is OK in that respect, though a little small for my taste.

The 40D is fiddly to use because of the number and complexity of its controls, though it can be used as a point-and-shoot. The Ixus has minimal controls and you hardly need to use the menus, which is good. There are a few annoying features, but essentially the controls are very well thought out to make life easy. The Lumix has about twice as many controls as the Ixus. They are more fiddly and not as intuitive as the Ixus buttons. However, they give you more control. The Ixus gives you minimal information - not even aperture and shutter speed. The Lumix gives plentiful information. Of course, the 40D gives you all the information and control that you can want. The 40D menus are well laid out and do not scroll off the screen, as in the 30D. There is an intimidating number of buttons, but you do get used to them eventually.

The two small cameras are both poor performers in low light. You can use ISO over 200 in both the Lumix and the Ixus but this is not recommended due to noise. Even the 40D has some visible noise above 400 ISO, though its shots are usable even at 3200 ISO. The two small cameras are also not so good at macro, because it is hard to get them to focus on the subject. The Lumix is not fast enough at focusing to allow one to shoot birds in flight. The Ixus lacks the zoom to even attempt this. This is where the 40D comes into its own. The 40D cannot do movies, whereas both the smaller cameras are quite good at this. Image stabilisation works well in all three cameras (but remember that you need to get stabilised lenses for the 40D).

Image quality is difficult to define, as it comprises many elements: sharpness, resolution (how much detail is captured, not the number of pixels), absence of noise, dynamic range (gradation of light and dark tones), colour accuracy, contrast, exposure accuracy, depth of field (this is not 'quality' but it can seem like it) and lastly and leastly, megapixies. The basics are: accurate focus, true colours and correct exposure. Resolution, noise, dynamic range, contrast, depth of field and pixies are all less important. A high megapixel count is only useful for large enlargements or for using just part of the image ie like extra zoom.

Regarding sharpness, this is a really tricky area. The reason why it is tricky is that each camera sharpens its photos in a different way and to a different degree. In most cases the Lumix shots were sharper than those made by the Canon 40D. There are two reasons for this. Firstly, the default sharpening in-camera is more in the Lumix. Note that this is something that you can set in both cameras, ie make the out-of-the-camera shots sharper or less sharp by adjusting the relevant settings. I think that most digital SLRs do not sharpen their output very much by default because the manufacturers want to give the photographer more control, ie to sharpen more or less as they desire. There are different sharpening algorithms to choose from in the PC, you can sharpen just part of a photo, and most importantly, some photos require more sharpening than others. If the camera applies the same strong sharpening to all your shots then some will look too grainy. All sharpening procedures produce artefacts, such as halos, speckling, excessive contrast in areas of minute detail, and harsh textures. It is all a matter of degree.

The other reason why many Lumix or Ixus photos are sharper than those taken by an SLR, and this applies particularly to close-ups and long telephoto, is depth of field. This is an area where the small sensor, short focal length camera really shines. Depth of field depends on the actual, not the 35mm equivalent, focal length of the lens. So if you are using a lens of 4.6 mm, like in the Lumix at wide-angle, then there is going to be much more depth of field than in the SLR with an 18 mm real focal length. Note, however, that sometimes you do not want a large depth of field, eg for portraits.

A third factor is that image stabilisation is important at the long telephoto end. If the SLR lens is not stabilised then it will suffer in comparison.

In most situations the image quality of the Ixus shots is comparable to that of the 40D.

This comes down to versatility and ease of getting great pictures. Perhaps even more importantly, which camera is best at liberating the hidden image-making artist? Which one allows you to be more creative and gives you the most pleasure?

The Ixus is fun because it is so convenient and easy to use. I don't hesitate to use it and this is a huge plus. The Lumix is also fun to use because you have the enormous zoom range at your fingertips. This gives you the feeling that it will photograph anything, whether near or far. The 40D is fun because it gives me the feeling I can photograph in unusual or difficult circumstances, that if I use it intelligently enough then I will get good shots. It holds out the promise (though it does not always deliver) of high-quality images. So each camera shines in a different way.

The Ixus is exceptionally easy to use. It can be carried anywhere, is nice and neat, with a high-quality metal body. The  interface is well-designed. The camera is very light and small. It is so small that you can shoot the underside of a mushroom, which you could not do with the other two cameras. The optical viewfinder allows you to see what you are photographing (except for close-ups, due to parallax) and to hold the camera against your head. Unfortunately, the next model (860) has already lost this excellent feature. Why Canon would chose to remove one of the best features of the camera is something only a marketing guru could explain. The Ixus has a very sharp lens.

Canon have done a great job of compressing a lot of features into such a small package. Image stabilisation works well. Large depth of field is another plus point. Another small, but surprisingly strong point in its favour is the absence of a lens cap to fiddle with. The zoom range is 28-105 mm equivalent, which is fairly useful. The controls are simple and easy to use (except for the power button).

It is hard to hold steady. I have unintentionally snapped my fingers many times. Low dynamic range, noise, poor low-light performance. The on-off button is awkward to use. Because it looks and feels like a toy it's hard for me to take photography seriously when I use it. Macro focusing is annoyingly unreliable, even on flat surfaces, so that it works about 80% of the time. Sometimes it is slow between shots. The colour violet comes out as blue. However, the biggest drawback for me is the lack of zoom.

The huge benefit of the Lumix is having macro and true wide-angle to extreme telephoto, ie 28 to 504 mm, all available immediately, without any lens changes. For such a versatile camera it is small and very light (407 gm). You can photograph people without their realising you are aiming a super-zoom at them. Above all, you can pretend to be a semi-serious photographer without denting your budget or your back! Large depth of field is another plus point.

The Lumix allows you to zoom to 804 mm (equivalent) if you decrease the mega-pixel count from 8 to 3. I compared this with just taking the centre of the 8 mp image. The results were similar, except that the 3 mp image was not sharp near the corners. So in conclusion, the extra zoom feature does not really do anything for you that you cannot do in the PC.

Poor low light performance, low dynamic range (highlights are washed-out), digital noise (coloured dots that should not be there) above ISO 200. The crappy lcd viewfinder and the even worse eye-piece one mean that you can never be quite sure what you are photographing. Essentially, the down-side of the camera is mediocre image quality and the inability to use sensitivity over ISO 200, without getting lots of noise. It is annoying that you have to remove the lens cap before turning on the camera. Battery life is somewhat short - after a few hours of shooting the battery starts to run out. Macro focusing is occasionally unreliable because one doesn't know where the camera is focusing.

Fast and responsive - instant turn-on and small lag between shots. It is a fully-featured enthusiast camera, so at least in theory, the 40D should be able to do almost everything the other two cameras can do, plus much more. The battery lasts much longer. The SLR viewfinder means you can see exactly what you are photographing through the same lens. The large sensor means good low-light performance with low noise. If you want to photograph birds in flight or do low-light photography (how can this be avoided?) then an SLR is the best option. I can shoot at 6 frames per second and use predictive focusing to snap flying pelicans. Most importantly, you definitely look like a serious photographer with one or two 40Ds across your chest!

It is big, heavy, complicated, with lots of buttons (25 different controls, not counting those on the lens). There is a sizeable learning curve to get to know its extensive capabilities. However, the 40D can certainly be used as a point-and-shoot. If you aren't a serious photographer then this camera is probably not for you. If you change lenses then sensor dust is a problem, though the 40D vibrates the sensor to clean it.

Most of the photos were taken in bright sunshine at and around a beach. All were compared pre-processing and at screen magnification (ie not 100% crop). The criteria used were: sharpness and visible detail, dynamic range (ie detail in shadows and highlights), noise (speckling and fringes), colour accuracy, exposure accuracy of subject, contrast (too much means a harsh and unsubtle image, too little and the photo looks washed out) and "overall" - which photo looks better?

Camera settings make a difference, eg you can increase the sharpness and contrast in both cameras. The Lumix defaults to considerably higher sharpness and contrast. Sharpness depends as much on in-camera sharpening as it does on the lens and sensor size and quality. After the test I set the 40D sharpening to its highest setting, giving results similar to the Lumix. The Lumix has a much bigger depth of field, which is useful for focus errors and for having the entire scene sharp, especially for macro. Note that if the comparison had been made in poor light I'd expect the 40D to do much better, if only because it is good at ISO 800 and above, whereas the Lumix should not be used above 200. All shots on the Lumix were taken at ISO 100.

I compared photographs of a feather at 100% crop and here the 40D showed better detail, whereas the Lumix had noise. Comparison of a townscape shot at 100% crop showed slightly better detail in the 40D. Some other shots showed clear superiority of the 40D at 100% crop.

All the above refers to the quality of the images. What about ease of use? The crappy viewfinder on the Lumix cannot compete with SLR viewing. The 40D is much faster to start up, more responsive to zoom and faster to focus.

Somehow, I am not convinced by this comparison. I still want to use my 40D in preference to the Lumix, and not just because the camera looks more impressive.

Note that due to its lack of zoom I could not take many of the telephoto shots with the Ixus that I took with the other two cameras. The lack of zoom on the Ixus is a big handicap. However, what makes the Ixus considerably more pleasant to use than the Lumix is the optical viewfinder. Both cameras showed a blue cast but the Ixus' was milder. The Ixus is a little softer, more subtle (less saturated colours), less contrasty. Similar depth of field.

Results for 26 similar photos taken with both cameras:

    Exposure accuracy 35% of the Ixus were better, 8% of the Lumix were better

    Contrast 31% of the Ixus were better, 23% of the Lumix were better

Results for 26 similar photos taken with both cameras:

    Exposure accuracy 27% of the Ixus were better, 23% of the 40D were better

    Contrast 50% of the Ixus were better, 19% of the 40D were better

Which is the best camera? Obviously, there is no simple answer to this question. The best camera for you depends on what you want to do, on how much effort you want to put into photography, and on how fussy you are about the results. Obviously, price is also a factor, though a second-hand digital SLR probably does not cost much. Size and weight are also important considerations.

If you want to take happy snaps wherever and whenever, at parties, while shopping, on the bus to work, then a pocket camera is unbeatable. You can attach it to your belt and forget about it till a photo opportunity calls. If you want to go on a photographic assignment, or bring back top quality shots from the Galapagos or the Himalayas, then an SLR is the best choice. The bridge camera lies somewhere in between. It has the focal length range of the SLR, allows you full photographic control, but represents a compromise in terms of image quality and ease of use. I find that I use the Ixus for quickness and convenience and the 40D for photo excursions and more serious efforts. I don't tend to use the Lumix so much.