Mirrorless Camera Guide 2024

When Panasonic and Olympus jointly launched the Micro Four-Thirds platform to produce high-image quality in a compact form-factor in 2008, these new Mirrorless Digital Cameras triggered a revolution in the industry. Suddenly, two companies that had an insignificant DSLR market share, led the fastest growing digital camera segment. With each next generation, Mirrorless Digital Cameras improved and eventually delivered on their promise, prompting virtually every other manufacturer to join with new systems, sometimes more than once. In the last two years, over 3X more mirrorless cameras were introduced than DSLRs , the symbol of image-quality for the last 2 decades, and just one more fixed lens cameras than mirrorless was launched.

This Mirrorless Camera Buying Guide explains what mirrorless digital cameras are, their advantages, the different types that exist and how each mirrorless system compares since these are system cameras compatible with certain lenses. Given that much had changed in the last two years, this mirrorless buying guide was completely rewritten in 2020. There are considerably more differences between mirrorless systems than among DSLR systems.

Origins

A mirrorless camera is an interchangeable lens camera without a reflex mirror, just like a car is a horseless carriage. Until mirrorless cameras were invented, digital cameras with interchangeable lenses all had a single lens and a mirror to reflect light towards an optical viewfinder. Such camera is called a DSLR which stands for Digital Single Lens Reflex. Mirrorless cameras also have a single lens but no mirror which allows its lens to be mounted closer to the sensor yet prevents them from having an optical reflex viewfinder.

Originally, the term SLD, which stands for Single Lens Digital, was used but made it easy to confuse with SLR. To further confusion, at least one manufacturer called their mirrorless cameras DSLRs! In the end, the more descriptive mirrorless name was broadly adopted, including here at Neocamera. The term DSLR is exclusively used for cameras with a Reflex optical viewfinder and the term ILC refers to both DSLR and Mirrorless.

Parallel to this revolution, cellphones improvements caused the digital camera market to implode. Compact digital cameras that delivered mediocre image-quality in a convenient size were supplanted by cellular phones which can be described the same way. This made mirrorless digital cameras a necessity to offer high image-quality in the most compact form-factor given that DSLRs were considered too large for anyone but professional photographers.

Mirrorless Image Quality

Fast forward to 2020 and mirrorless digital cameras are now capable of exactly the same image quality as DSLR. Among the top 10 cameras with the best image-quality, six are mirrorless. Among the top 20, nine are. The simple reason is that the same sensor technology is used across all these models, technology made by Sony which manufactures more than 50% of sensors on the planet and has been a leader in image-quality.

While technology constantly improves, the most significant factor for image-quality is sensor-size. All else being equal, a larger sensor will always deliver better image quality since it gathers more light than a smaller one. DSLRs mostly use APS-C and Full-Frame sensors, except for Medium-Format used in by Pentax. The image-quality from a modern APS-C sensor is excellent with Full-Frame and Medium-Format sensors delivering even better performance. All these sensor-sizes are used inside mirrorless cameras too.

Mirrorless digital cameras also use Four-Thirds sensors which are smaller than APS-C and exactly 1/4 the surface area of Full-Frame sensors. While they cannot completely match the image-quality from larger sensors, their output is very good and this smaller size brings other advantages. Two smaller sensors-sizes were previously used by mirrorless cameras, 1" and 2/3", but no such camera has been produced in the last 5 years.

The diagram shown on the right shows sensor sizes used among current mirrorless cameras. All rectangles are to scale and even coincide with actual sizes on most computer displays. There are actually two very similar variants of APS-C with the one used by Canon being fractionally smaller.

Mirrorless Camera Size

The size of mirrorless cameras varies tremendously, from highly-compact Micro Four-Thirds models to huge Medium Format ones that exceed the size of DSLRs. With a given sensor-size, a mirrorless camera can be made smaller than a DSLR, yet some manufacturers chose to deliver more capabilities within the same size rather than go smaller. The main size saving comes from the depth of the camera body since there is no need to leave room for a swinging mirror. Some height can also be saved by moving the viewfinder or using a more compact unit which has to be done carefully for ergonomic reasons.

A camera needs a lens in order to form an image. While there is a clear focus on camera size, it is crucial to understand that total bulk depends on both the camera and lens. Removing the mirror allows cameras to be made significantly smaller but it has minimal impact on lens size. Designing optics is a complex science. While certain lenses can be made smaller when designed specifically for a mirrorless camera, generally the size of optics is mostly determined by sensor-size. This is exactly why compact cameras have small lenses that correspond to their small sensors. The same applies to cellphones. Even weight saved is minimal since most the size-reduction comes from moving relatively empty space within the camera.

All this means that a mirrorless camera and matching lens can only be somewhat smaller than a DSLR having the same sensor-size. In the best case, a Full-Frame Mirrorless manages to compare in size to an APS-C DSLR when including equivalent lenses. This makes for some fairly small APS-C mirrorless camera and lens combinations with the greatest advantage for the Micro Four-Thirds system.