Q When would you select a digital SLR over a mirrorless camera system? What are your thoughts on the different SLR brands?
A Either type of system can perform most any photographic task. I use my Micro Four-Thirds mirrorless system for travel, family and general, all-around use. I prefer SLRs in the studio, for low light and for action photography.
Most digital SLR systems have been adapted from legacy 35-millimeter systems. The advantage is possible compatibility with older lenses. The disadvantage is extra weight and bulk.
Most digital SLRs have a sensor that is smaller than 35mm film, so the bodies and lenses are larger than they need to be to handle the sensor size. It is with this in mind that Olympus and Panasonic developed the Four-Thirds system, an SLR system "designed for digital" from the ground up. Panasonic discontinued its SLRs to concentrate on the Micro Four-Thirds mirrorless interchangeable lens camera system. Olympus still manufactures a few Four-Thirds SLRs, but now focuses most of its efforts on Micro Four-Thirds, too.
Some SLRs do have large sensors the size of 35mm film. These are referred to as "full frame" cameras. These are the ultimate for image quality, but are expensive, demand the best optics and create large files that quickly fill up your memory card and hard drive. Most digital SLRs use an "APS-C" sized sensor that is smaller than full frame but a bit bigger than Four-Thirds.
Canon and Nikon are referred to as the "big two" and dominate the SLR market. These are the most comprehensive systems in the industry and include a wide variety of specialized pro bodies and expensive, high-performance optics. If you're a budding professional or a serious wildlife photographer with a big budget, these are the systems for you. Consumers can hardly go wrong with any camera from either manufacturer.
I'm not as impressed with either company's inexpensive lenses, and that is one of the reasons that better value can often be found elsewhere.
Pentax is my choice -- and has been going back to the film era. I love the way the cameras feel in my hands and love the color and sharpness of the pictures. Pentax's inexpensive kit lenses are excellent, and Pentax also offers a unique line of tiny fixed-focal-length lenses with top-shelf optical performance. Pentax SLRs have image stabilization built into the camera body, which means every lens you mount is stabilized. The top-rated, high-performance Pentax K-30 is one of the best values available in a digital SLR. It sells for a street price of $662 with 18-55 lens.
Sony has a full line of SLRs, including both APS-C and full- frame models. I haven't tested one, but colleagues who have were impressed.