Mirrorless Camera Guide
Mirrorless digital cameras are usually mid-size cameras supporting interchangeable lenses. They are system cameras and each model gives access to a set of compatible lenses. In this guide to mirrorless cameras, you will learn what these cameras are good for, plus how mirrorless systems presently compare. There are much more differences between mirrorless system than DSLR systems, so it is critical to consider both the camera and system before buying.
A mirrorless camera is an interchangeable lens camera without a reflex mirror, the same way that a car is a horseless carriage. Until the appearance of mirrorless cameras, digital cameras with interchangeable lenses were all DSLRs which are defined by having a single lens and a reflex mirror to reflect light towards an optical viewfinder. Mirrorless cameras still have a single lens but no optical viewfinder. The original term, SLD which stands for Single Lens Digital, was easy to confuse and therefore the more descriptive mirrorless name was broadly adopted.
While compact cameras were always appreciated for their size, the same could not be said about their image quality. Meanwhile, DSLRs that consistently deliver excellent image quality are frequently abandoned because of their bulk. Mirrorless cameras were invented to produce high quality images from a compact camera.
Mirrorless Image Quality
The high image quality traditionally exclusive to DSLRs comes from their large imaging sensors which gather more light than those of compact cameras. Mirrorless cameras currently have sensors of various sizes, from compact-size 1/2.3" ones, all the way to the same full-frame size used by top-of-the-line DSLRs. Image quality varies accordingly, hence there is a greater discrepancy between mirrorless systems than among DSLRs.
The diagram shown on the right displays sensor sizes used in 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.
Only a single mirrorless offers a full-frame sensor at this time but more are expected to appear this year. Except for the smaller two sizes, all of them remain in-use among DSLRs.
Mirrorless Camera Size
The size of mirrorless cameras varies equally widely. Despite being called relatively compact and having official measurements similar to compact cameras, mirrorless cameras take on bulk once a lens in mounted. Once ready to shoot, most mirrorless cameras are the size of a typical ultra-zoom, only with higher quality and a shorter zoom.
A camera's sensor-size influences its operational-size because larger sensors require larger lenses. As image quality gets closer to that of a DSLR, so does total size. However, there are so many variables involved that there is no simple relation and some combinations of camera plus lens are actually smaller than a smaller-sensor equivalent.
Mirrorless vs DSLR
Mirrorless cameras are evolving faster than other types of cameras. Being the youngest type of digital camera is the main reason and there is also the opportunity for smaller players to take the lead. The speed of this evolution plus tremedous variations among mirrorless cameras means that there are also plenty of misconceptions.
Top 10 Mirrorless Camera Facts
- Image quality from the very best mirrorless cameras is comparable to that of a DSLR using a sensor of the same size. The latest Micro Four-Thirds cameras produce output which is very close for typical print sizes until moderately high ISOs when compared with cropped-sensor DSLRs.
- A lens influences the image quality of a mirrorless camera just as it does for a DSLR. To get the best out of a mirrorless, a sufficiently good lens must be used. The typical kit zoom lens sold with cameras is generally built for compactness rather than quality. Often a better prime kit lens is offered instead.
- In good light, some mirrorless cameras are capable of focusing as quickly as mid-range DSLRs. The autofocus performance drops in low-light, as it does for a DSLR, but the gap widens then. The majority of mirrorless cameras focus noticeably slower though.
- Shooting speed of mirrorless cameras exceeds that of the fastest DSLRs. Continuous shooting up to 60 FPS or 15 FPS with continuous autofocus are available at full-resolution and so are shutter-speeds exceeding 1/8000s.
- Mirrorless cameras are quieter than DSLRs because they do not have a reflex mirror to move between shots. Some use an electronic shutter which makes them nearly silient. This is highly advantageous when shooting in quiet environments.
- The preview on a mirrorless camera is electronic, just like a fixed-lens digital camera or Live-View on a DSLR. The preview varies considerably in terms of sharpness and accuracy between models. The best offer a sharp Exposure-Priority display and EVF. When resolution is too low, it is hard to confirm focus. When the update rate is slow, following action is difficult.
- Mirrorless cameras are power-hungry because their sensor must constantly feed the digital preview. Plus, mirrorless cameras are often fitted with smaller batteries. As a result, the average battery-life comes to 366 shots-per-charge, compared to 987 for DSLRs.*Based on current models as of February 2013.
- Mirrorless cameras are strong in terms of video features. It is possible to shoot video with the camera at eye-level and continuously autofocus while recording, either by on-sensor Phase-Detection or highly optimized Contrast-Detect proceessors and lenses.
- Only a handful of mirrorless cameras are aimed at professional users and certain high-end features such as weather-sealing are extremely rare among both cameras and native lenses.
- Lenses mount closer to the sensor on mostExcept for Sony SLT and Pentax K mirrorless models. mirrorless cameras compared to DSLRs. This makes them more adaptable to use legacy lenses, although features such as autofocus are commonly lost.
SLT - Mirrorless with Pellicle Mirror
Sony makes cameras the size and shape of DSLRs which use the same sensors and lenses. They call these SLT cameras for Single Lens Translucent. They use a semi-transparent mirror to reflect around 30% of light to focus and metering sensors. Contrarily to an SLR, an SLT has an EVF. This viewfinder can preview exposure, color, white-balance and focus, up to its maximum resolution.
As intermediate cameras, all current mirrorless models provide a number of advanced features, although their accessibility greatly differs. Particularly, all of them include: full manual-controls, manual focusing, custom white-balance, continuous drive and full 1080p HD video capture. Nearly all models also sport a hot-shoe. They have a wide range of sensitivities and shutter-speeds as well.
The high-speed CMOS sensor and continuous live-view allows mirrorless cameras to provide features usually unavailable to DSLRs. This includes sweeping panorama capture and shooting of images in multiple aspect-ratios which only a handful of DSLRs can do.
Manual focusing has traditionally been difficult with anything other than an optical reflex viewfinder. However, the majority of mirrorless cameras offer a Manual Focus Assist function which magnifies part of the image to make manual focusing easier. A few add something called Focus-Peaking which highlights edges of in-focus areas, something which is impossible to do with an OVF.
As with all interchangeable lens cameras, the aperture range and minimum focus distance of mirrorless ones is determined by the lens being used. Most lenses support screw-on filters to modify incoming light.
Flash, either built-in or add-on, is limited by a sync-speed just like it is on DSLRs because all current mirrorless cameras use a focal-plane shutter and electronic shutters are still relatively slow. Expect sync-speeds between 1/60 and 1/250s.
Proceed to Step 2 to learn about Mirrorless Camera Systems from each manufacturer. There we compare what each brand has to offer considering cameras and lenses as a system.
New Cameras & Lenses
Pentax WG-30w16 Megapixels Fixed Lens
5X Wide Optical Zoom
Waterproof to 12m
Canon EF 400mm F/4 DO IS USM IIStabilized & Weatherproof
Canon EF Mount Prime Lens
Canon EF 24-105mm F/3.5-5.6 IS STMStabilized
Canon EF Mount Zoom
Canon EF-S 24mm F/2.8 STMCanon EF Mount Prime Lens
Sony Carl Zeiss Vario-Tessar T* FE 16-35mm F/4 ZA OSSStabilized & Weatherproof
Sony E Mount Zoom
Panasonic Lumix G 14mm F/2.5 ASPH IIMicro Four-Thirds Mount Prime Lens
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