However, unlike a digital SLR (DSLR), mirrorless cameras don't have a mirror box -- hence the name 'mirrorless' -- which is used in a DSLR to bounce a scene from the lens up into an optical viewfinder so that you can frame your shot. The mirror in a DSLR sits in front of the sensor.
In a mirrorless camera, there is no mirror. The lens sits closer to the sensor, and you frame your shot by looking either through the LCD screen on the back of the camera, or through an attached electronic viewfinder (instead of an optical one).
The biggest advantage of mirrorless cameras is that, because they don't have a mirror box, they can be a lot smaller than a digital SLR -- some models are only just a little bigger than a typical compact camera. This makes them a much more attractive proposition for anyone who would like to carry an advanced camera with similar manual controls to a DSLR camera, but without the inevitable bulk that is present in a DSLR. However, you will still have to carry around a couple of lenses, or at least one versatile zoom lens, just like you would with a digital SLR.
Manufacturers currently offering mirrorless cameras are Sony, Olympus, Panasonic, Fujifilm, Samsung, Canon, and Nikon. Prices can vary greatly for these types of cameras, with professional-calibre models often found for close to $2000. Furthermore, the lenses for such cameras can be expensive in general. The best value for money can be had from twin lens kits, which come with a combination of wide angle and telezoom lenses that can allow you to cover most bases when it comes to common photography tasks, from sweeping landscapes, to closer-up details.
As with all camera ecosystems, you will need to find one that has the lenses that suit your style of photography, and then figure out how much you can expect to pay for the available lenses. Just because mirrorless cameras are smaller, it doesn't mean the prices are always smaller.
Perhaps the best part about mirrorless cameras is that they have been created with mainstream users in mind. Many come with highly capable automatic modes, lots of scene modes, sometimes 'art' modes, and they usually have clean control layouts that make them simple to operate. On many models, there is a 'what you see is what you get' live view of the scene you are about to capture, which can make using the camera a lot more intuitive when it comes to changing exposure settings.
Some things to look for when buying a mirrorless camera (lens selection aside) include a hinged screen so that you can either tilt it up or down (or swing it around to take 'selfies'), a decent handgrip size so that it will be comfortable to hold, and an adequate array of manual controls. For example, if you want to take complete control of the exposure, look for a camera that has two separate dials for the aperture and shutter.
Shooting in the dark
The ability of mirrorless cameras to take photos in dark situations has improved vastly over the years, with many cameras these days allowing you to take photos while using a high sensitivity setting -- some being capable of ISO 1600 or greater without noticeably hampering the image quality.
In the past, low-light shooting was an advantage that DSLR cameras had over their mirrorless counterparts, mainly due to having bigger sensors capable of capturing more light easier. The sensors in mirrorless cameras are small in some models (such as the Micro Four Thirds sensor that can be found in Panasonic and Olympus models) while others have APS C-sized sensors that are similar to mainstream DSLR cameras. Sensor density can be anything from 16 megapixels to 28 megapixels, with the higher density sensors allowing you to crop your photos a little more without losing too much detail.
Optical image stabilisation
Optical image stabilisation (OIS) is a technology that can help low-light shooting as well. This technology allows the camera to compensate for the slight shaking that can occur when a camera is used at a slow shutter speed while being held in the hands rather than sitting on a tripod. Cameras that have optical image stabilisation built in to the body are beneficial in that the stabilisation technology can work with any lens that is attached. Cameras that don't have stabilisation built in to the body must rely on the lens to have it instead.
Hold the camera before buying it
There is a temptation to buy technology online these days, but if you're in the market for a mirrorless camera, we recommend that you do make the journey to a camera store to check out various models -- if, of course, you live within cooee of a camera store and it's easy to make the journey. The feel of the camera is important, and you'll want one that sits comfortably in the hands, with good balance and weight.
You'll also be able to ask about lenses and see first hand how big the lenses are. While the camera bodies can be small, various lenses will make the camera bigger, and it's important to know this if your main aim is high mobility.
Mirrorless cameras were formerly known by names such as 'compact system cameras', 'mirrorless interchangeble lens cameras' (or MILC), and 'interchangeable lens cameras'.