I have long been a passionate defender of the DSLR. I have watched from a bit of a distance as mirrorless cameras have gone from pipedream to ambition to possibility and on to fad, Zeitgeist and now revolution.

Mirrorless cameras stand on the brink of becoming the industry standard, ousting the technology that has been the mainstay of all photography for nearly 40 years. But what’s so special about them? And why is this happening now?

I don’t think it is possible to understate quite how momentous this shift really is. Single lens reflex systems have been the only way to operate for as long as I have worked with cameras. The concept alone has always made perfect sense. The most accurate way to compose and frame an image must surely be to see exactly what the film or sensor will see. In the case of an SLR, they achieve this by showing you the exact view through the lens via a mirror, then lifting the mirror to expose the sensor or film. It’s that simple solution that the single lens reflex camera offered, and what made it a technological marvel in the first place.

The original SLR

When the first single lens reflex camera was created it offered photographers, for the first time, the ability to see what the lens was seeing, when the lens was seeing it, almost real time. The standard before that was the twin lens reflex camera, introduced properly to the mass markets in the 1920s. The TLR allowed the photographer to see almost what the main picture-taking lens was seeing. But, as we know, there was a slight offset and inherent drawbacks to that system. When the single lens reflex came along in 1985 it changed the world.

Canon AE-1 Program
Canon AE-1 Program – one of the most popular 35mm film single lens reflex (SLR) cameras ever made. First launched in the late 70s.

Over the course of 40 years of technological advances, the single lens reflex system was perfected to such an extraordinary length that not only could photographers happily snap away images of more than 100 megapixels, they could do it repeatedly, multiple times per second, the mirror rising and falling quickly, smoothly and with little or no bounce in between each frame capture.

Mirrored systems and shutter systems on modern DSLR are often good for more than 200,000 shutter actuations. Make no mistake, the modern digital single lens reflex camera is a technological marvel in itself.

TLR to SLR to DSLR to…

If you follow the timeline of camera development through the last hundred years, where we have arrived today was always on the cards. The moves from box cameras, to twin lens reflex, then single lens reflex and on to the digital single lens reflex, were all leaps in technology. The advancing improvements were driven by a need for the image in the viewfinder to more accurately represent the resulting captured image.

Yashica 635 antique classic TLR medium format camera
Yashica 635 antique classic TLR medium format camera, but capable of taking a 35mm film as well. The top lens is the focusing lens, the bottom the “taking” lens.

Take that progression one step further and surely the end goal must be for the image seen in the viewfinder to actually be the image captured.

The mirrorless camera arrives

And this is where mirrorless cameras come in. Ever since the arrival of the Canon 5D Mark II and its game changing video, the days of the camera mirror have been numbered. What the 5D Mark II told us was that, way back in 2008, it was possible to live preview and record in 1080p from a digital sensor. 

Canon 5D mark II
Canon 5D mark II – this camera marked a leap forwards for digital singe lens reflex (DSLR) technology, but did it also spell the eventual end of the DSLR, and the start of the mirrorless revolution?

With the mirror locked in the up position, the Canon 5D Mark II was able to send a signal direct to both the main screen and the processor, and get an accurate representation of what the sensor was doing. For the first time you were able to see exactly what the sensor was seeing and exactly what the sensor was recording, with no requirement for any mirrors or prism box. And so, in one giant leap forward for DSLRs, the DSLR was dead.

DSLR is dead. Long live mirrorless.

But why, I hear you ask, didn’t mirrorless cameras suddenly take over back then in 2008? There’s an easy answer… the technology just wasn’t quite ready yet. Whilst the boffins at Sony, Canon and Nikon had figured out how to allow live view on the main monitor on the back of the camera and record in HD direct from the sensor, they couldn’t adequately push that through a viewfinder and they couldn’t use that system as standard for all camera operations because it caused overheating and excess stress on the circuitry. They couldn’t make the system reliable and durable enough for it to be a professional tool.

Those of you who had the glorious pleasure of working the video functions of the 5D Mark II will be crying out now that it was a wonderfully reliable piece of kit. And it was, I am not attempting to claim that the signal is intermittent, or that there were any major issues of getting the signal from the sensor to the monitor. But the 5D Mark II, and almost all cameras of that era which attempted to run live signals direct from the sensor for long periods of time, had issues of one kind or another.

Stills cameras that do video

Most cameras like this, and in fact many cameras still today that are designed primarily for stills but also like to turn their hand to video, suffer from overheating problems. The issue is that if a camera is not 100% designed for video, they tend to be built with smaller “pipes” – ie circuitry and chips – and large quantities of information being pushed through small pipes causes problems.

Dedicated video cameras tend to be big, relatively bulky pieces of kit. And necessarily so, because moving all that information around is no easy task. It generates heat, and lots of it. And the smaller the camera body, the more difficult it is to get rid of excess heat. 

Sony Alpha a5100
Sony Alpha a5100 – a mirrorless APS-C camera with a flip up screen, making it a favourite with vloggers, but it has serious overheating issues when capturing video.

Take a recent case in point for me – the Sony Alpha a5100. I had one of these as a cheap vlogging camera, but didn’t realize that, even when recording at a meagre 1080p, it is well known to be plagued with heat issues. The documented figures for most people have it running for approximately 20 minutes before it overheats and shuts down, but I was finding it was more like 10.

The problem? Small camera + chip and circuits designed primarily for stills = limited recording time before system meltdown.

Electronic Viewfinder

The other problem, and barrier in between the mirrorless camera and its future, has been the EVS (electronic viewfinder). If you spend some time looking into pixel counts of screens on digital cameras, and pixel counts on EVFs, you’ll have realized a few things.

Firstly, you’ll have realized that when you put the pixel count of the rear screen / monitor next to the pixel count of the sensor, the numbers don’t even come close to matching. In fact, even on the remarkable Sony A7III, one of Sony’s most recent releases (as of 2019), the sensor has 24 million pixels… the monitor has less than 1 million.

Sony A7R2 electronic viewfinder (EVF)
The Sony A7R2 has an 800k pixel (2.4M dot) electronic viewfinder, similar to the A73

Compare that to what the EVF can display and the numbers are even less impressive – 24 million pixels on the sensor, just under 800k pixels on the EVF.

Those numbers might seem a little crappy, but bear in mind that the EVF on the Sony A7III is only half an inch big. That’s a half inch screen with a thousand pixels along the long edge! That’s insane! And it should give you a good idea of why we couldn’t adequately do this ten years ago.

What camera manufacturers are now achieving with EVFs is nothing short of remarkable.

The mirrorless boom

So why are mirrorless cameras now taking over, when the technology has really been around for ten years or more?

The simple answer is, we are now ready for them! Technology has advanced far enough to allow the mirrorless systems to be convenient, intuitive and reliable… and in many ways better than a DSLR. 

But there’s a bigger element of this to consider, and that is us as humans, us as photographers and our collective psychology. People (and photographers) tend to resist major change. Especially when it is change away from a system that genuinely works well. If it ain’t broke etc. DLSRs worked, and so it’s unsurprising there was an inertia hampering major switches to new systems.

Embracing the digital era

There is also a much broader shift in thinking amongst the whole population, not just for photographers. If we look at the last 20-30 years, it’s only recently that we have started to accept fully digital systems. We don’t feel the need for electronic devices to have a non-automated option. Even washing machines and driers have changed massively in the last two years. They now offer non-automated, program-yourself options on all models, to offering only automated selections on almost all models.

The fact is that we have now, finally, started to trust the machines. In a way we have never done before. We now have enough faith in the digitalized world that we don’t think the automated options are going to let us down. We all now believe that they are good enough to rely on, and that we can now trust them. And we’re learning that they are quicker, easier and better than doing it ourselves.

Technology in photography

We live in an era of technological surge, especially in the world of photography. 30 to 50 megapixel sensors are now almost standard from pro-sumer level cameras upwards. Even in consumer-focused APS-C cameras it’s hard to find anything below 24MP. Face tracking, eye detection, internal five axis image stabilisation, NFC, built-in Bluetooth and Wi-Fi… The list goes on and on. New tech appears every day, and it’s being perfected with remarkable speed and efficiency.

The Sony A7R2 - a high performance mirrorless camera
The Sony A7R2 – a high performance mirrorless camera with a 42.2MP sensor and high end video capabilities.

Imagine explaining to a photographer 20 years ago that all this would be available in just a couple of decades. What we’re working with now is the stuff of the future. The world is forever disappointed that we have not yet achieved hover boards a la Back To The Future II. By this benchmark we often feel a little underwhelmed by our achievements. But in the world of camera technology, I would argue that we have achieved more in a shorter space of time than anyone dreamed might happen.

And so here we are with mirrorless cameras. Photographers are now ready to rely on an electronic-only view finder and screen. We trust in the systems and the manufacturers enough to no longer have any physical link between the lens and viewfinder. We believe, now, that the technology has become good enough and reliable enough that a digital link between the real world and our monitoring systems will be sufficient, even at a professional level, in all situations… and for the life of the camera. And that is a huge shift in thinking.

The mirrorless camera has both ridden the wave of digital acceptance, and driven it faster and farther. 

They’re here, they’re reliable, they’re simpler and more intuitive than DSLRs… and they’re here to stay! Much as it pains me to admit it.


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