I recently bought a Nikon D70 SLR camera. Although my Canon Powershot A70 has served me well since I bought it in August of 2003, it was starting to show its age and there is a whole lot one can do now with a digital camera that was not so easy back two years ago.
Although I first considered a Panasonic DMC-FZ20 (and, later, the FZ5), the D70 went down in price by a good deal upon the announcement of the nearly-identical D70s and that gave me enough incentive to buy one. What follows is a comparison of my experiences using a digital SLR and my experiences with various fixed-lens cameras. It is my hope that this will be useful for someone considering a similar purchase.
The important disclaimer first: a fancier camera does not necessarily mean you will take better pictures, it just gives you more control over the factors involved in taking better pictures.
What I like about my SLR
I can use any lens I want as long as it fits the lens mount. By definition this is not true for a fixed-lens camera.
With a larger sensor, it's actually possible to get real depth-of-field control. With a fixed-lens camera, everything is in focus no matter what (macro mode excepted), even at something like F2.8. Whether you care about depth of field or not, it is impossible to deny the other advantages of a larger sensor, especially the sheer amount of detail it gives you. Better still is the lack of noise. Pictures taken by my D70 at 1600 ISO are cleaner and crisper than pictures taken by the Powershot at 200 ISO. To be fair, a more recent fixed-lens camera probably fares much better here.
The images also have better dynamic range and less of that ugly purple fringing. A blown highlight is still a blown highlight, but they don't look anywhere near as ugly and are much easier to avoid if you're trying to do so.
Because the body is so large, there's plenty of room for dedicated buttons for most anything I'll need to change more than once or twice. Because the camera has a usable optical viewfinder, I don't have to worry about the LCD screen slowing everything down. If I press the shutter release button, the picture is taken and I can take another one almost instantly. Did I mention that, because most everything is mechanical rather than electric, the battery lasts a very, very long time?
When I hit the on switch, the camera is immediately ready to take a picture.
And I'm just generally more a fan of the ergonomics with a the SLR body than I was with the fixed-lens body. So what if it's largely subjective?
What I could do without
The camera is very large and very heavy. The lens alone is nearly as big as the entire old camera. This isn't an issue when I'm using the camera, but it is certainly a hassle when I'm not. Most fixed-lens cameras will fit in an average pocket.
Opening up the body by taking off the lens allows for dust to get on to the protective glass plate above the sensor. It will show up on your images. Luckily, it only shows up under certain conditions and can be removed from the final image when removing it from the sensor itself is too much work.
And there's the fact that it costs a whole lot more money than a fixed-lens camera. Darn.
What I preferred about the Powershot
Macro mode doesn't require a separate lens. If I want to take a picture of something close to the camera, I just press the macro button and it works.
As stated before, the Powershot fits into the pocket of just about any pair of pants I own. The D70 does not.
The same screen is used for taking the picture and reviewing the picture. Very easy.
Much less noise is made by the camera when taking the picture due to the lack of a mirror.
What made me choose the D70
I first began to consider seriously a digital SLR after reading the Photo.net review of the Pentax *istDS. The lack of worthwhile affordable lenses put me off, though, as did the fact that most of the other reviews for the camera weren't as gushing. I didn't look too hard at the Olympus system, mostly because it is limited in available lenses, and the ones that are available are rather expensive.
So, like most people, I was looking at Canon and Nikon. There is more than enough enthusiasm to go around for the 20D and the D70, but I found the positive comments about Nikon to be more interesting. Nobody really seems to care quite so much about the Digital Rebel line. A direct comparison between the 20D and D70 did sway my opinion toward the former for a bit; people like to complain about the size of the D70's viewfinder, but I only really noticed when comparing it directly with the 20D. The 20D has a much nicer viewfinder, but in the end I went with the camera that was several hundred dollars less expensive. I also went with the camera whose kit lens was regarded to be pretty good rather than nothing special.
The various cameras really aren't all that different in most ways, the D70 just fits my needs a better than anything else. Now I just need to knock over a bank so that I can afford the DX wideangle and a good telephoto zoom.