Digital SLR cameras evolved from their film forebears, and many manufacturers chose to continue supporting the mounts they were already using - conveniently so for those with a few lenses. Until the recent arrival of CSCs, DSLRs represented the only serious consumer-oriented option for high-quality imaging, but even today they remain the weapon of choice for the professional and enthusiast user.
Best DSLR: top cameras by price and brand
Sensors - size matters
There are many reasons why DSLRs are popular with keen and professional photographers. Of course, some of this is down to what a photographer is accustomed to using, and, should they already own a collection of lenses, the idea of trading everything in holds little appeal.
For many professionals, though, it's the size of the sensor which is an important factor. Full-frame sensors such as the Nikon D600, Nikon D800, Canon 6D and Canon 5D Mark III have three major benefits: first, they allow for larger photosites (aka pixels) than smaller sensors. Not only does this make them better equipped for capturing low-light scenes with minimal noise, it also helps to preserve a wide dynamic range.
Second, they can fit a greater number of pixels than APS-C and other smaller types, assuming the pixels are the same size. This is an important factor in relation to the level of detail which may be resolved, and may even be crucial depending on how the images will ultimately be used.
Finally, because they apply no crop factor to lenses, full-frame DSLRs are far more suitable for wideangle work, such as for landscapes, architecture and reportage.
The large variety of lenses developed for the more common systems also helps to ensure that the pro is never lacking, and here CSCs still have some way to go.
For press and wedding photographers in particular, the ability to use full-frame models for video shooting is also a bonus, particularly when the combined effects of large sensors and specialist lenses is considered. The DSLR video sector in particular is seeing a lot of development, not just from camera manufacturers, but also third parties who produce microphones, supports and other accessories commonly used by the DSLR videographer.
Professional-level DSLRs also have large pentaprism viewfinders; these make use of glass prisms and superior optics which display a scene with clarity and brightness. Cheaper DSLRs also use optical viewfinders, but they often contain mirrors rather than glass.
Called pentamirror viewfinders, these help to keep a camera's overall weight and price down. But they can't quite compete with pentaprism viewfinders for brightness, and often only show around 95% of the scene.
Build and functionality
It's true that DSLRs priced under £1,000/AU/US$1,500 face considerably more competition from the CSC market than pro-level models, given the similarities of pricing and specification between the two camps.
Regardless of the category under which a DSLR falls, though, their build quality and ergonomics make them ideal for more professional use, particularly in situations where they may encounter adverse conditions or where they may face being bashed around.
Some photographers simply find CSCs too small, and prefer the larger build of a DSLR. The current trend for CSCs to offer much of their operation through touchscreens rather than physical controls, combined with the different methods of achieving focus, means that for action and sports photography in particular the DSLR still holds an advantage.
Many DSLR users are used to shooting with an optical viewfinder and are understandably reluctant to switch to a camera which can only render an electronic facsimile of the scene in front of them - however detailed it may be.
However, it's worth bearing in mind that EVFs are improving all the time, and they show the image as it will be captured, taking into account the colour, white balance and exposure settings.