WHILE by no means a flop, the most innovative idea to come out of the Japanese camera industry in decades—the mirrorless digital camera—has not exactly taken the photographic world by storm. By dispensing with the mirror in front of the shutter of a digital single-lens reflex (SLR) camera—which redirects the image created by the lens to an optical viewfinder above, before flipping briefly out of the way for a picture to be taken—the mirrorless camera promised to be lighter, smaller and quieter, with a specification only marginally less than its bulkier big brother at the pricier end of the market.



It proved to be all those things and more. And thanks to its ability to accomodate lenses of different focal lengths, the mirrorless camera offered greater versatility and better images in packages that were not all that larger than pocket-sized compact cameras at the lower end of the market.



Introduced by Epson in 2004, but popularised largely by Panasonic and Olympus from 2008 onwards with their jointly developed “Micro Four Thirds” format, the mirrorless camera was heralded as the savior of the industry's struggling second-tier of photographic firms—ie, all those below Canon and Nikon (the latter two accounting for more than half of all camera sales between them). By offering something technically different, the mirrorless camera provided second-tier firms with something to challenge the duopoly’s long domination of the digital SLR business.



Sitting between compact cameras at the low end of the market and entry-level SLRs at the high end, the mirrorless format encompassed benefits of both, with few of either’s drawbacks. As such, the mirrorless camera was supposed to appeal to fledgling photographers moving up from point-and-shoot cameras, as well as serious photographers seeking something more portable to carry with them everywhere (on the principle that the best camera is the one you have with you).



Unfortunately, the shutterbugs who were supposed to flock to the new cameras found other ways of taking pictures. A number of serious (“prosumer”) amateurs and even a few professional photographers have become staunch mirrorless fans, especially now they provide almost as much control over shooting conditions as full-sized digital SLRs. But more mainstream consumers have generally shied away from them, at least in America and Europe, though less so in Japan.



This is not because such people are happy with their pocket-sized point-and-shoot gadgets, and see no reason to move up market to mirrorless models. If anything, they have traded down. Indeed, the compact-camera business has been in free-fall since people started relying on smartphones to take pictures instead. Compact camera sales dropped more than 40% last year, according to IDC, a market research firm.



Over the past couple of years, smartphones like Apple’s iPhone and the numerous Android equivalents have been incorporating camera sensors every bit as good as those used in point-and-shoot cameras; Nokia’s Lumia models match all but the best compact cameras equipped with zoom lenses. More importantly, smartphones offer something cameras have been unable to match: seamless connectivity.



Whereas popular photography was once all about making prints for family albums, its main purpose today is for uploading images to Instagram, Twitter or even Facebook. Here, the ability to transmit pictures instantly to social networks with the swipe of a finger has immense appeal. Smartphones do this better than even the fanciest of digital cameras. And while camera-makers have rushed to add WiFi to their latest models, the implementations have left much to be desired. Gadget users today value instant connectivity above everything; certainly, far more than picture quality, given the poor graphical resolution of the web generally.



That has left mirrorless cameras squeezed between increasingly more sophisticated smartphones that cost much less, and SLRs that cost not all that more. Indeed, with entry-level SLRs priced as loss-leaders (to lock customers into a manufacturer's system of camera mounts and lenses), mirrorless cameras are being forced into market niches. By no measure are their makers (Panasonic, Sony, Olympus, Fujifilm and Ricoh in Japan, plus Samsung in South Korea) on the verge of collapse. All are part of large electronics groups. But lacking robust sales, industry watchers fear they could be starved of research and development funds. Were that to happen, the innovation they have brought to the photographic world could falter.



That would, indeed, be a pity. Mirrorless cameras embody a level of technical creativity the camera industry has not seen in ages. Take the digital SLR, which crams a number of decade-old developments between the lens and the image sensor. Among other things, there is an image stabiliser, to correct for hand-shake; a low-pass filter, to eliminate moiré fringes caused by repetitive pattens in fabrics and the like; and a dust-reduction mechanism, to clean the sensor after a lens has been changed.



Lodged in there as well is a sophisticated phase-detection system for focusing the lens automatically. This uses a secondary mirror (attached to the main one) along with a dedicated sensor to measure the convergence of two light beams, plus a servo motor to snap the lens into focus. This is an expensive piece of machinery that requires precision assembly and skilled craftsmen for installation and calibration. A good deal of a digital SLR’s cost is wrapped up in its phase-detection auto-focusing system.



To accommodate these extra components, along with the mirror box for the optical viewfinder and the auto-focusing mechanism, has traditionally required the “flange-back” distance—the distance from where the back of the lens mounts onto the camera to the sensor’s imaging plane—to be fairly long. That is why digital SLRs are bulkier than their analogue brethren and can never be as slim as range-finder models, let alone compact cameras.



However, dispensing with the digital SLR’s mirror assembly eliminates not only the optical viewfinder and its chunky pentaprism, but also the expensive auto-focusing mechanism. With the mirror removed, the flange-back distance can be reduced significantly. In the process, the camera body becomes more compact, lighter and cheaper to build. Lenses are then more compact, lighter and cheaper as well.



With the optical viewfinder gone, mirrorless cameras have to rely on either an LCD display on the back of the camera body for taking pictures with arms outstretched, or an electronic viewfinder for eye-level shooting. Electronic viewfinders use a small LCD inside the camera to display the image falling on the sensor. Being electronic, it can overlay all sorts of information on the viewfinder screen for the photographer to see at a glance. Optical viewfinders offer little more than the basics—ie, film speed, shutter speed, aperture and possibly battery life.



To keep costs down, mirrorless cameras initially adopted the much cheaper contrast-detection method for automatic focusing used in compact cameras. Relying on the main sensor to do all the donkey work, this needs no costly additional components. But the focusing process—involving repeatedly testing a small part of the image, to measure its sharpness, coupled with incremental focusing adjustments—requires a lot of computation. As a result, focusing can be a bit too slow for action photography (eg, sports, birdwatching, etc). To overcome this, recent mirrorless cameras use a separate sensor to perform both contrast- and phase-detection calculations, and can focus as fast as all but the best SLRs. Mirrorless cameras with hybrid auto-focusing are now the norm.



As for sensor size, mirrorless cameras started off using mostly the Micro Four Thirds format pioneered by Panasonic and Olympus, with a sensor area 30% less than the standard APS-C sensor used in digital SLR cameras, but nine times greater than those used in compact cameras and smartphones. While Panasonic and Olympus have stuck with their Mirco Four Thirds sensor size, most mirrorless makers have now migrated to the bigger APS-C sensor. With its top of the range Alpha 7R, Sony now sells a mirrorless camera with a full-frame sensor (ie, the size of 35mm film). The only other mirrorless camera-maker to do so is Leica, though it charges twice as much.



Both Canon and Nikon have ventured into the mirrorless arena, but neither has embraced the format whole-heartedly. Until they do so, mirrorless cameras will remain niche products. Yet, the many technological improvement they embody could unleash a wave of innovation that both Canon and Nikon sorely need. More exciting models from the camera world's two leading makers would give the whole industry a shot in the arm, and bring benefits to shutterbugs everywhere.



