Anyone who has been involved in photography long enough should be familiar with the sometimes contentious debate about the differences, whether real or imagined, between film and digital. Which exhibits better dynamic range? Which has better resolution? How much better? The digital medium has established itself as the imaging standard, and most who still engage in the film versus digital discussion are generally content to concede that both can co-exist.
Arguments over the merits of film photography as compared to digital photography have died down as technology has continued to advance, but it is this ever-advancing technology that is responsible for the persistence of still another topic of debate within the photography world: DSLR versus mirrorless.
Are DSLRs, with their bulky bodies and slapping mirrors, really dinosaurs? Are mirrorless cameras truly the future of photography? These questions don’t have simple “yes” or “no” answers, and that is a good thing for everyone. But if you find yourself in a position of having to choose between the two technologies, here are a few key factors to keep in mind.
Size and Weight
Digital SLR cameras are bigger, bulkier and heavier than their mirrorless counterparts, as they need to house a mirror and prism mechanism.
Mirrorless cameras obviously lack a mirror; nothing sits between the rear element of the lens and the imaging sensor. This design helps cut down size and weight significantly. However, if there is an upside to the more robust DSLR bodies, it is better ergonomics.
DSLRs employ an optical viewfinder as their primary means of previewing an image. When you look through an optical viewfinder, you are looking at the exact scene the camera will capture when you press the shutter button.
Mirrorless cameras use an LCD screen or an electronic viewfinder (EVF) to preview images. The EVF essentially provides real-time electronic rendering of what you would see through an optical viewfinder. While mirrorless cameras such as the Fujifilm X-T3, X-H1 or GFX series, Olympus’ OMD series, or Sony’s A7 and A9 lineup, Nikon's Z series, feature very good EVFs with minimal lag and blackout where you will experience the feel and responsiveness of an optical viewfinder, but the technology overall is continuing to improve. Electronic viewfinders have yet to edge out optical viewfinders for many photographers, while others are perfectly content with their EVF.
When it comes to autofocus speed, DSLRs have traditionally enjoyed bragging rights. However, various mirrorless releases from the likes of Sony (a6500, A7 series, A9), Panasonic (GX9, GH5), Olympus (OM-D E-M1X, OM-D E-M1 MARK II) , Nikon (Z6, Z7), Canon (EOS R) and Fujifilm (X-T2, X-H1, GFX series) each have at some point made pretty bold claims about AF speed.
“Real-world” testings have proved that some mirrorless cameras performed exceptionally well in comparison to the high-end DSLRs. Even sports and wildlife photographers have started using mirrorless cameras as evidenced here on the job. This is due, in part, to the implementation of hybrid autofocus — an AF system that combines both phase detection and contrast detection technologies.
Given that DSLRs have been the dominant format for so long, it makes sense that there is such a comprehensive selection of lenses — both native and third party — available for these cameras. Mirrorless cameras, for example, Sony, have a comparatively small (but growing) stable of native lenses available and third party lenses are becoming more available in the market compared to a few years before, for Sony mirrorless cameras.
The main exception to this, of course, is the Micro Four Thirds mirrorless format that have more than 70 native lenses available, the bulk of which are manufactured by Olympus and Panasonic (the companies behind the Micro Four Thirds format). Lenses from third-party manufacturers like Sigma, Tamron, and Rokinon/Samyang have helped fill in gaps left by the lack of native mirrorless lenses. Mirrorless cameras are also easily adapted to fit virtually any manual focus legacy lens.
Due to their larger sensors (APS-C or full-frame) DSLRs were at one time considered the clear winners when it comes to image quality. But today, even the small Micro Four Thirds size sensor has advanced to the point that overall image quality leaves little to be desired for mirrorless camera users. Upping the ante, even more, is the incorporation of APS-C size sensors (standard in most Fujifilm X cameras, Sony A6000 series), full-frame sensors (Sony’s A7 series and A9, Nikon's Z series, Canon) and medium format sensors (Fujifilm GFX series) in mirrorless bodies.
The ability to shoot video is a standard feature on any camera these days. Mirrorless cameras tend to be a better option for those looking for fast and accurate focusing/tracking in video mode (mirrorless cameras are sometimes spoken of as video cameras with the ability to do still shots). Comparatively few DSLRs are equipped with the means — namely, on-sensor phase-detection points — to challenge mirrorless systems in this area. Furthermore, while both mirrorless and DSLRs are capable of broadcast quality/HD video, newer 4K/Ultra HD is currently far more likely to be found in mirrorless bodies. Canon’s 1D C, released in 2013, became the first DSLR to incorporate 4K resolution.
The Bottom Line
The items above aren’t the entirety of all the things one might take into account when deciding between a mirrorless or DSLR camera; if battery life, for example, is a particularly important factor for you, then you might be happier with a DSLR (or stock up on extra batteries if you prefer a mirrorless body). Everything in photography is indeed a compromise. But all the options generated by all the competition is good for consumers. The debate over which technology is “better” is mostly pointless. Make your decision based on which camera offers features that are best suited to your style of shooting. That is all there is to it, really.