SLR cameras have long been a staple of photography, dating back to the days of film. Short for Single Lens Reflex, the SLR gets its moniker from a spring loaded mirror behind the lens which reflects the view from the lens back up to the user. When the shutter button on an SLR is pressed, the camera flips that mirror up to momentarily expose the film behind it, and your view is preserved as a photograph. In these modern times, digital SLRs replace that film with a sensor, but have kept the ergonomics and mechanics of the original SLR design, including even the familiar slapping sound of the mirror when the shutter is activated.
A classic film-based Canon SLR with the reflex mirror showing.
But this whole concept is antiquated in the digital age. The purpose of the mirror reflex system was to see your shot before you take it, as there was no other accurate way to preview what you were capturing. However, a digital sensor can send a live preview to a viewable display before capturing the photograph, as we see in cell phones and point-and-shoot cameras. No mirror required. In fact, the flipping mirror system not only adds weight and bulk to the camera, it actually adds a somewhat delicate moving part that wears out over time and needs to be serviced. Imaging giants Canon and Nikon have made a business keeping the SLR camera alive and in the hands of everyone—from professional photographers to soccer moms—who care about image quality. Sure, you can get a smaller point-and-shoot camera from those guys, but everyone knows their DSLR models are capable of better pictures.
A modern age Canon DSLR. Note that even though the camera is currently powered off, the optical viewfinder is working.
However, not every camera manufacturer has such nostalgia for the SLR. Fuji, Sony, and Olympus—despite a history of manufacturing and selling SLR systems—now propose that a camera does not need a mirror to be great. Joined by the likes of Panasonic, Samsung, and a growing number of other camera brands, a new style of interchangeable lens cameras has become popularized that ditch the mirror and prism that gives the SLR its moniker. This new breed of is commonly referred to as mirrorless interchangeable lens cameras, or ILCs for short.
A Panasonic ILC (left) showing its sensor compared to a Canon DSLR (right), which has the sensor blocked by a mirror.
The question is, are they really just as good as traditional digital SLR cameras?
Theoretically, image quality should be the same because the mirror only serves ergonomic purposes. I say theoretically because the reality is that mirrorless ILCs got off to a slow start that held them back technologically. Too expensive for the point-and-shoot enthusiast, manufacturers tried to appeal to DSLR shooters as a smaller and lighter alternative. To keep the size and weight down, the camera makers ended up with flimsier build quality and smaller sensors, often resulting in lower image quality compared to their larger DSLR counterparts. It also didn’t help that Canon and Nikon released their own ILCs as well; they also made sure to keep them consumer grade and separate from their prosumer and professional grade DSLRs.
This is why professionals and enthusiasts refused to take DSLR alternatives seriously for years. Thankfully, that’s beginning to change. When the Olympus OM-D was released as a professional grade ILC with a rugged, weather-sealed body, it appears to have caught the attention of street photographers. New offerings from Fuji now have more dynamic range than similar class DSLRs, and Sony has really done something special with its full-frame mirrorless A7 series. Word on the street is that Nikon’s flagship D800 DSLR has the same sensor as the Sony A7R. However, the A7R is smaller, lighter, cheaper, and compatible with more types of lenses via ring adapters. The arguments to stick with a traditional mirrored DSLR camera are getting weaker and weaker with each new ILC that comes out.
From left to right: An Olympus ultra-compact ILC, a standard form Panasonic ILC and a Canon DSLR. Note the size and thickness difference required by the reflex mirror on the Canon.
So, are DSLRs dead? No, not quite yet. For starters, Nikon and Canon have the most native lens options available and have no plans to stop producing DSLRs. Because most professionals and enthusiasts are heavily invested in one or the other’s lenses, it’s going to be a while before that slows down and eventually gives way to more modern designs. Mark my words, it will eventually. Mirrorless is the future.
As an enthusiast photographer and Nikon fanboy, I agree with some reserves. True, there are mirrors capable of at least the same image quality as their SLR counterparts, one just need to take a look a Sony’s range of full frame mirrorless, they are simply awesome.
That said, and apart from the endless range of less of Canon and Nikon, there’s the question of the OVF, yes, the mirror is a nuisance, but IMHO, no LCD screen, no matter how good, it’s yet capable of being as good as seeing with your own eyes, some of us still love composing with an optical viewfinder.
A quick peek at Nikon’s new D750 will convince anyone that they’re far from dead yet. Still, it’s hard to imagine mainstream users using DSLRs in 5-10 years, and for good reason, I must admit that I’m seriously tempted by Sony’s full frame mirrorless, but my D90 is still a solid performer and budget is not at its best right now so… :)
I predict that just like the switch from film to digital, there will be a hardcore contingent that will swear that the old way (DSLR) produces superior pictures. But really if there is any difference at all, it’ll just be different, not objectively better. And that contingent will die off and there will be no more DSLRs.
ONE purpose of the mirror reflex system is to see your shot before you take it, but the OTHER purpose is to enable phase detect autofocus. When the mirror is down, part of the image is directed to the viewfinder, and part of the image is directed to the phase detect sensor. When you click the shutter, the mirror gets out of the way, and the image falls directly on the sensor. Mirrorless systems don’t have that ability, and therefore they don’t focus as fast, and they can’t replicate the same ability to stay focused while tracking moving objects.
The latest mirrorless cameras have sensors that have some phase detect sensors mixed in among the pixels, which is great, and I’m sure they are constantly improving their performance and have some digital magic to hide them in the final image, but it’s one of the reasons why DSLRs still have some advantages over mirrorless.
Two problems.
1) When SLR was created, AF didn’t exist yet. The purpose back then WAS just to see your shot before you take it, as mentioned above. It DID just serve ergonomic purposes, and the later integration of AF was tied into how the cameras were already operating (since the mirror is down when you want to focus, the phase detection system was designed to work with the mirror down).
2) Phase detection can exist on the sensor these days. Quite a few mirrorless cameras already have them, and most of the new release announcements list PDAF (phase detect auto focus) as a feature. I’ve seen it on Olympus, Sony, and I think even the new Samsung NX1. None of them have mirrors!
All I can say to this is that I miss my Minolta X700 SLR. I don’t like digital at all!