Say Hello to Our New Mirrorless Overlords
Those Single Lens Reflex cameras with their movable mirrors have had a good run. But is it time to say hello to our new mirrorless camera overlords? Asking for a friend.
To put all this in context, it's worth noting that cameras haven't always had mirrors. There once was a time when cameras had a single, straight-through image path, light coming in through the lens in the front, and on toward the film plate at the back. In order to focus and compose the shot, photographers had to remove the camera back and fit it instead with a ground glass screen onto which the scene was projected upside down. When everything seemed in order (other than being upside down that is), the film back was reattached, and the photograph taken. Being a photographer back then must have been cumbersome.
To simplify the process, twin lens cameras started gaining preference. As their name implies, such cameras featured two objective lenses of the same focal length, mounted in line with each other. The bottom lens (or taking lens) allowed light to reach the film back. The top lens projected a parallel image toward a separate viewfinder. Needless to say, such a large camera with dual lenses would have been awkward to hold up to your eye. Still too cumbersome.
To make being a photographer more comfortable, another innovation was needed. And this time, it was all done with mirrors. Enter the Twin Lens Reflex (TLR) camera, a new-fangled improvement on the twin lens camera that used an angled mirror to reflect the image from the top, focal lens upwards into a ground glass screen one could look down on. The word "reflex" in the new designation referred to the reflection introduced by the newly added mirror. This new focal screen design meant the camera could be held much more comfortably and stably against the body. And the photographers rejoiced. They were at last comfortable.
But they still weren't happy. Even though the two lenses in their cameras were right next to each other and facing in the same direction, the image seen by each differed ever so slightly due to something known as "parallax error." The easiest way to understand parallax is to look at something in the distance through your left eye, and then through your right. Just take turns closing first one eye, then opening it and closing the other. The further away the object is you are looking at, the less of a difference you will notice between dependent on which eye you are looking through at the time. But if you switch to looking at something closer to you, the distance between your eyes will become more relevant, and the view seen by each will become increasingly disparate. Each has its own point of view, so to speak. To extend this experiment, look down at the nose on your face and repeat the described parallax test. You will find that your left eye is looking at the completely opposite side of your nose as your right sees. This shifting perspective from two parallel but separate viewpoints is parallax error. And it gets worse the closer you are to your subject.
This brings us up to the era of camera optics most of us are more familiar with, the era of the Single Lens Reflex, or SLR camera. As should be obvious from its name, the SLR camera dispenses with one of the two lenses that defined the Twin Lens Reflex. In this case, the single lens serves double duty, with the mirror now able to flip up out of the way. With the mirror lowered, the focused image gets reflected up from the angled mirror into the viewfinder. When the mirror is flipped up, the exact same image is allowed to reach the film plane at the back of the camera. Although there have been some SLR cameras fitted with ground glass focusing screens, the majority return to eye-level viewfinders made possible by the addition of a pentaprism used to reorient the image. I guess the weight savings from only needing a single lens meant that photographers were again OK with holding cameras up, and their subjects were OK with no longer being forced into having what few family photos they own all shot from waist high. It is a bit of a silly vantage point, come to think of it. And so both photographers and their subjects were happy.
All this change was part of an ongoing evolution in how we see what it is we are taking pictures of. What might at first seem to be a trivial problem turns out to be nothing of the sort. You see, or should I say, you don't see, because the physical existence of the camera naturally wants to be in the exact spot that blocks our seeing what lies on the other side. Early photographers had to move the film out of the way and put it back when ready to shoot, then we moved to using two lenses fit next to each other. And finally, we hit on the idea of a reflex mirror sitting behind a single lens, but one that could be temporarily swung up out of the way to allow light from that single image to be sent two different directions, up towards the viewfinder, and straight through to the film. Or digital sensor, in a modern context.
And it's specifically this modern digital context that allows us to revisit this age-old viewfinder problem once again. Digital rules the day. And now with each generation of the digital photography era, sensors and other electronics have evolved and improved. First, we had sensors that overheated if you shoot a longer exposure image, requiring extra post-processing to clean up the mess of noise. Gradually, we got better single frame sensors and eventually ones that were good enough support limited "live view" and even video capture modes. Display screens have improved too. Not only are current LCD screens bigger and much higher resolution than were the ones found on early digital cameras, their images can be seen more clearly across an increased range of viewing angles and lighting conditions. All of these are ingredients to the present mirrorless technological leap.
Once digitized by the sensor, a mirrorless camera can repurpose a single image or video stream both to an electronic viewfinder (EVF) and, when the shutter is fired, to the memory card for be saved for posterity. With digital, we no longer need line of sight manipulated by mirrors to see what we are photographing. We just need a whole bunch of expensive, state of the art electronics. See, progress.
This really is the next step in an evolutionary line going back to the earliest of cameras. Removing the mirror will enable camera makers to build full frame cameras that are much more compact than their SLR ancestors. And perhaps even more important, it is enabling them to shorten the lens mount flange distance to open up new possibilities in lens design that will benefit us all. Think faster apertures and wider-angle focal lengths for starters.
So, what will not having a mirror cost you? Well, you won't be able to impress your friends with the fact that your camera is bigger than theirs is, or that yours has mirror lock-up and theirs doesn't. And, thanks to the FTZ adapter (or whatever Canon calls theirs) it seems you won't be able to complain too loudly about being forced to buy all new lenses. And I guess you won't be able to look at yourself in your camera's mirror to see if you've got something stuck between your teeth. Not that I've ever done that, you understand. Asking for a friend.
So, are these things really ready for prime time yet? Well, I'm not sure yet. The jury is still out on this, what with Nikon's new mirrorless Z6 and Z7 just starting to ship, and Canon's full-frame mirrorless strategy not yet officially unveiled. Personally, I'd bank on it taking another few generations for the skeptics (and perhaps realists) to quiet down. For full disclosure, I have not ordered a Nikon Z7 and am more than happy with my manly, mirror-endowed D850. But I'm just saying, mirrorless is the future.
Say hello to our new mirrorless overlords.
So, are we happy yet?