Digital SLRs are mainly intended for professionals who need the extra functionality that the setup provides, e.g.:
– Seeing exactly what’s going on the “film”, so you know exactly what you’re getting and don’t have to crop later. Cameras with a seperate viewfinder are generally way off.
– You need to see things in real time, for sports and such; LCD displays have some lag.
– Wide range of interchangeable lenses, so you can have 17mm super-wide for closeups of big things, to 300mm (or more) for small things far away, especially sports.
– Long battery life, so you can work all day in fairly remote locations; this is one of the main drawbacks of electronic viewfinders.
– Quick response time, for sports and other action shots. You need the shutter to trip immediately when you push the button.
– Ability to manually focus.
Point-and-shoot cameras with electronic viewfinders work fine for taking a snapshot of little Jimmy at his birthday party, but you really need an SLR to get a closeup action shot for the newspaper’s sports page.
You don’t realize how much nicer an SLR is until you use one. I love my (well, my employer’s) Nikon D1.