I use a Digital SLR. The Canon 1ds MARK2. It is currently one of the best Digital SLR around and has won many awards. It takes an amazing 16.7 Mega pixels in 16 bit colour. Each image has a file size of 95MB. This means the image can be zoomed in on without loss of sharpness. Having such a powerful camera, it is important not to compromise its quality by having cheap lenses no matter how versatile they may be, so for a wedding for example I use the Canon 24-70L series lens mainly, plus at times the Canon 70-200L IS (Image stablizing) lens. Both of which are highly respected by critics and very bright (f2.8) which makes them useful for low light conditions. For home portraits I set up studio lighting with soft diffusers and various backdrops. I carry also a second camera for backup for all photographic work, the Canon D400 10 Megapixel DSLR which can take the expensive lenses mentioned above.
Sharpness:

The top image shows Big Ben from across the River Thames using the above mentioned camera at 70mm (24-70L lens).

The images below have not been zoomed in on using a zoom lens but show the detail that is present in this orginal file.

You can actually count the tiles on the clock face on image on the bottom right. If the whole image was dispayed at this (100%) resolution you would need a screen that is over 6 feet wide by 4 feet high! (@72dpi screen).