CHAPTER 1
The Mirrorless Revolution
THE REVOLUTION HAS BEGUN
There’s a revolution happening in photography. While not as dramatic as the move from film to digital, it’s nonetheless every bit as important. The revolution is not how we record images, but what we use to record them. It is the change from the near universal use by professional and serious photographers of digital single lens reflex (DSLR) cameras to mirrorless interchangeable lens cameras (MILCs).
As Kenji Tanaka, Senior General Manager of Sony’s Digital Imaging Business Group was quoted as saying in a DPReview.com interview on March 16, 2018, “If cameras are going to develop, manufacturers have to develop mirrorless technologies.”
By mirrorless technologies Mr. Tanaka is referring to compact cameras that don’t have mirrors that flip out of the way when an exposure is made, as do DSLR cameras. And though similar to compact mirrorless cameras, the distinguishing feature is the ability of MILCs to interchange lenses.
Through the fusion of modern design and technology, MILCs are capable of outperforming DSLRs in almost everything from quality to continuous shooting, with enhanced focus, exposure control, and monitoring. MILCs also have major advantages when it comes to video capture, an increasingly important part of professional practice.
The one major objection to MILCs will be all but overcome by the time this book has been published: limited lens selection. Not only are the major players, Fuji, Olympus, Panasonic, and Sony, adding new focal lengths to their line of lenses, but Tamron, Tokina, and Sigma, makers of third-party lenses, are rushing into the market with professional quality glass.
Whether they know it yet or not, before long most professional photographers will be working primarily, if not entirely, with MILCs.
What Is a Mirrorless Interchangeable Lens Camera?
Mirrorless cameras have been around since the beginning of photography. In fact, all 35mm cameras were mirrorless until the introduction of the Zeiss Ikon VEB Contax S film camera in 1949, Figure 1.1. This camera featured an eye-level optical viewfinder (OVF) that with the aid of an internal mirror allowed the photographer to see through the lens. Seeing through the lens was not new to photography, it’s how you used a view camera dating back to the 1830s. But seeing through the lens of a handheld camera was revolutionary.
The modern style of 35mm handheld camera became known as the Single Lens Reflex camera (SLR). The use of the word “reflex” in the name has nothing to do with the mirror flipping out of the way the moment the shutter is released. Reflex is a physics term for reflecting light, so the word refers to the mirror itself, which is why it also appears in the name of Twin Lens Reflex cameras (TLR), in which the mirror doesn’t move.
Prior to the Contax S, photographers either composed and focused on the back of a large format view camera using a magnifier; or composed and focused through a viewing lens mounted above the taking lens on a TLR camera, Figure 1.2, or composed and focused through a window to the side of the taking lens in a viewfinder camera, Figure 1.3. By viewing through the lens of the Contax S the photographer could accurately see what they would record.
The immediate precursor to the current MILC was the Epson R-D1, developed by Seiko Epson and Cosina Voigtlander in 2004 (Figure 1.4). The R-D1 was a cross between a rangefinder-style camera, using digital capture and manually focused Leica lenses, and a current generation MILC.
There were two limiting factors in the R-D1 and subsequent early attempts at MILCs. The first factor was the exclusive use of contrast detection autofocus (CDAF) that took about twice the time to acquire focus compared to phase detection autofocus (PDAF). Professional photographers covering sports, street photographers, or anyone photographing action of any kind were unable to effectively use these cameras. With the introduction of hybrid autofocus (hybrid AF), combining CDAF with PDAF pixels built into the image sensor, MILCs are now able to offer fast and as accurate continuous AF as DSLRs.
The second limiting factor was the lack of an EVF with the resolution, clarity, and response of direct optical viewing found when using an OVF. EVFs found on less expensive MILCs and most compact mirrorless cameras still suffer these effects. But today, those found on high-end MILCs, such as the Sony a7RIII, Nikon Z 6 and Z 7, Fujifilm X-T2, Panasonic Lumix GH5S, and the Leica SL, are nearly indistinguishable from an OVF with additional advantages, such as the ability to overlay real-time information in the viewfinder window such as histogram, focus peaking, and Zebra, as well as being able to preview exposure adjustments in real time.
Until these two obstacles were overcome DSLR cameras ruled the professional and “serious” photography world. Not that DSLRs ever outsold compact digital cameras aimed at the “Mom & Pop” market, they didn’t. The market for inexpensive point-n-shoot family-style cameras far outnumbers the market for pro cameras and always has. But for anyone serious about image making, the MILC has changed the game.
MILCs versus DSLRs
DSLRs use the same design as 35mm SLR film cameras. A mirror inside the camera body reflects the light coming through the lens to a prism and into the viewfinder allowing you to see directly through the lens, Figure 1.5. When you release the shutter, the mirror flips up, the shutter opens, and focused light strikes the image sensor, recording the image.
With a mirrorless camera, light passes through the lens and directly onto the image sensor, there is no mirror or prism. A preview of the image is either displayed on a rear LED screen, known as Live View (LV) or on a second eye-level EVF screen. Due to their lack of a mirror, the mechanism necessary to move it out of the way, and a pentaprism, MILC cameras can be made smaller, lighter, and mechanically simpler.
A MILC camera also known as a Compact System Camera (CSC), can do anything a DSLR can do; but a DSLR cannot do everything a mirrorless camera can. The only thing that holds mirrorless cameras back is the choices made by the camera makers. The lack of a feature or an inadequate function, such as slow AF has more to do with poor design choices or keeping cost down than the lack of technology. This is one reason it’s always a good idea to check out current camera reviews on reputable web sites such as Camera Labs, DPReview, TechRadar, or Imaging Resource.
How Are They Alike?
Both MILCs and DSLR cameras have these things in common:
• Image stabilization (IS) for low light and handheld photography. IS can be found in either the camera body, known as In-body Image Stabilization (IBIS), or in the lens, simply known as IS, and sometimes it can be found in both, depending on the system used. Most MILCs now have some form of IBIS.
• There are two types of AF: phase detection and contrast detection. When MILCs were first introduced they relied on slower but more accurate contrast detection, whereas DSLRs mostly used phase detection. It didn’t take long for faster focusing phase detection to be introduced into MILCs. Most MILCs and some DSLRs now have “hybrid” AF systems combining contrastAF with phase-detection pixels to further refine focus.
• Both systems can achieve excellent still-image quality, it’s all in the size and quality and design of the sensor, and the number of megapixels, with more not necessarily being better.
• Both systems, DSLRs and MILCs, are capable of producing high-definition (HD) and 4K video. However, DSLR makers currently are only incorporating 4K into their high-end pro-line cameras, whereas 4K is not only in top-of-the-line MILCs but is rapidly making its way into less expensive models, such as the Sony a6500 and the Fujifilm X-T2.
In case you’re wondering, there’s no reason 4K can’t be used in any camera, it’s just that DSLR makers use 4K as one of the methods to differentiate their pro cameras from their mid-range enthusiast cameras.
• Image and video playback, along with image sharing, is equivalent between DSLRs and MILCs. Both camera types can display images on their screens or using an HDMI output. Many now include Wi-Fi for sending images to smartphones for quick image sharing with clients and all your best new friends on Facebook. The Nikon Z 7 can connect the camera to your computer via Wi-Fi, something even the flagship Nikon D850 DSLR can’t do.
The Advantage of MILCs over DSLR Cameras
MILCs are still in a relatively early stage of development. As mentioned, any apparent lack has more to do with poor design or cost cutting than a fault in the system. Unless you’re into conspiracy theories and believe that the major players are holding back technology to sell new model cameras every six months.
Two examples of faulty design are the one mentioned above, poor AF performance in the original MILCs that relied entirely on contrast detection and slow frames per second (fps), and small buffers (burst speed).
All three issues have been successfully addressed. With the introduction of hybrid phase and contrast detection focusing systems MILC AF can be faster and as accurate as any DSLR.
EVFs allow for the inclusion of features to enhance exposure and focus that cannot be included in a DSLR OVF due to technical limitations. EVFs can also simulate the exposure and white balance the camera will record.
The body of a DSLR must be bigger so the mirror can flip up without scraping the back of the lens. Removing the mirror and the mechanism that goes with it helps to significantly lighten the size and weight of the camera.
Because there’s no mirror to flip out of the way, MILCs can expose more fps than DSLRs. Whereas DSLRs have hit their ceiling at about 12fps, the 20MP Olympus OM-D E-M1 Mark II can expose 18fps with continuous AF tracking. While other MILCs are not yet as fast, it’s just a matter of time before they...