Single Lens Reflex cameras (SLRs) have been the mainstay of professional photographers and enthusiasts for decades. And for good reason. The image quality and shooting capability have always been the best you can get (in a reasonable size and price anyway).
Single Lens Reflex is a nerdy way of saying what you see in the optical viewfinder is a live view through the lens. The image coming through the lens is directed up to the viewfinder via a mirror and a pentaprism (another nerdy word for more mirrors) and then through the optical viewfinder. It's great to know exactly what you are shooting. And it makes composing an image easier because you are not distracted by bright sunshine making it hard to see what's on the screen on the back of your camera, or by everything outside the frame when composing using the screen.
Okay, that makes sense, right? So we're all good? Nope, not anymore we're not. Things change, usually for the better. Disruptive technologies (see my blog post on disruptive tech below!) have a way of making the good old way not so good anymore. And the SLR is the living dead of cameras. Why? I'm glad you asked. Electronic viewfinders, that's why! An electronic viewfinder (EVF), unlike single lens reflex and pentaprism, is exactly what it sounds like. Instead of a bunch of mirrors directing the live image from the lens through the viewfinder, the camera has an electronic image come from the sensor to an electronic viewfinder. So they can look a lot like a dSLR, but smaller, and lighter, and usually faster. And photographers like faster. Who wouldn't want faster?
Why are they smaller, lighter, and FASTER!? Simply because the mirror takes up space. Get rid of the mirror and the camera can be made smaller and lighter. With an SLR, every time you take a photo, the mirror has to flip up out of the way so the light can reach the sensor. Snap! Then the mirror returns. The viewfinder goes momentarily dark. It's called viewfinder blackout. When you take a picture, you don't actually see what picture you took. You see the moment right before and the moment right after. And black in between. Since there's no mirror on a mirrorLESS (get it!) there is shorter screen blackout (or none), depending on the camera design. There are too many other advantages of mirrorless cameras to go into here, so I'll focus on smaller, lighter and faster.
The key here is the electronic viewfinder. They've been around for years. But it's just in the past year or two that they've advanced to be good enough to replace an optical viewfinder on SLRs. And that is the moment when SLRs went from dominant to zombie. It's only a matter of time before SLRs become a niche camera. Here's how I know.
I've always shot Canon SLRs. I have so much Canon gear that I (should) have a special seat at the table at their annual stockholder's meeting. So I'm kind of connected to Canon through my investment in their lenses (cameras are actually only about 1/5th of my investment in camera equipment. most of it is in lenses). I like Canon, but they're living in the past. They don't offer a good mirrorless option, instead focusing on bringing old tech to the market. Confession: I recently tried my first mirrorless camera (I feel like I'm cheating on Canon). The Samsung NX1. The NX1 is an amazing camera. It competes with Canon's new 7D Mark II. The 7D II is a nice camera, but it's already outdated. It was outdated two years before they released it. The image quality is great. But the NX1 beats the Canon at almost every spec. It's much faster frame rate, higher resolution, waaaay better video, smaller, lighter, and FASTER! And the NX1 is cheaper.
Sounds great. But I didn't keep the NX1 and reluctantly bought the 7D II instead. Why, if the NX1 is so much better? Changing cameras isn't a simple as changing the brand of your jeans. For better or worse, changing cameras also means changing lenses. And as I mentioned above, that's a big deal, and Canon knows it. But besides the big lens change, the NX1 came up short in two areas...autofocus and behavior of the viewfinder. The autofocus on the NX1 is very good, probably good enough for 90% of what I shoot and 100% of what most people shoot. But the Canon autofocus is better. The second way the NX1 came up short was how the viewfinder is programmed to function. It's a really nice electronic viewfinder. It's so good it's easy to forget it's not optical. But for some strange reason, during burst shooting, Samsung has programmed the viewfinder to show a series of still images, instead of the live image. So essentially you see a series of photos that you just took. It makes tracking a moving subject (i.e. runner, snowboarder, or misbehaving child) very difficult. I have no idea why they would do this (Samsung...not the misbehaving child), and it's something that could be easily fixed in a firmware update, which to their credit Samsung is doing about once a month. I really liked the NX1 and wanted to keep it. But I just couldn't make it work for what I needed right now.
So I'm not quite ready to switch to mirrorless...yet. But the 7D II will probably be the last SLR I ever buy, and I wouldn't be surprised if in a year I have switched to mirrorless. I get a lot of people ask me for camera recommendations and now I recommend a mirrorless. And I would recommend the NX1 without hesitation. I've also been recommending the Sony a6000. It's a smaller form factor mirrorless camera, but with amazing autofocus, resolution and frame rate.
So the SLR lives on for now. But really, it's just a zombie and will be truly dead in a year or two.