DSLR vs mirrorless cameras in 2020: which type is best? We help you choose

(Image credit: Canon)

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What's different
Focusing
Viewfinders
Battery life
Size
Lenses
Video
The final word

The decision about buying a DSLR vs mirrorless camera can be tricky. They both take the same pictures, of course, but they use very different designs. Some say that the DSLR is dead and that mirrorless cameras are the future, but Canon and Nikon have both released new DSLRs so it's clear they don't think so.

In late 2019 Canon launched the EOS 90D, a DSLR which can do anything Canon's mirrorless cameras can, right down to live view autofocus and video capabilities. And in early 2020 Nikon launched the D780, a DSLR that takes the sensor and live view autofocus system from its mirrorless Z 6 model to offer all the technical advantages of the mirrorless design.

The fact is, both camera designs have pros and cons, so we will explain what the differences are, whether they are likely to matter to you, and which type of camera might be best for what you want to photograph. There are lots of myths about DSLR vs mirrorless cameras that need busting, particularly the idea that mirrorless cameras are somehow intrinsically better. In reality, it's not always about what these different types of camera can do, as much as the type you most like to use.

If you're a big-time Canon fan, for example, the best Canon camera could turn out to be a DSLR or a mirrorless model, and it's the same with the best Nikon cameras. Our list of the best mirrorless cameras is changing constantly as new models keep appearing. The best DSLR cameras, by contrast, change much more slowly.

Some say DSLRs are dead in the water and that mirrorless cameras are the future. We think it's a bit more complicated than that.

2018 was a huge year for mirrorless camera systems as Panasonic, Canon and Nikon all introduced professional full frame mirrorless cameras.

The mirrorless revolution

2018 was a big year for mirrorless cameras. The arrival of the Nikon Z 6 and Z 7, the Canon EOS R and the Panasonic S1R and the S1 meant that mirrorless cameras could now compete with DSLRs at every level.

The mirrorless camera design is compelling. Many photographers have ditched their DSLRs and swapped to the mirrorless format. Many others, however, are more hesitant, and they continue to ask the same question: are mirrorless cameras really better than DSLRs?

The short answer is that mirrorless cameras are certainly more capable than DSLRs in many respects, and they hold a number of different advantages. However, there are many reasons why novice users and seasoned pros alike would still be better served by a DSLR – not least because a cheap DSLR camera is still the most affordable way to get into serious photography.

So over the next few pages we’ll take a look at key areas of technology and design to try to answer that mirrorless vs DSLR question once and for all.

What's different

DSLRs and mirrorless cameras both show the scene through the camera lens itself as you compose the picture, but the way they display it is completely different.

The SLR design was invented long before digital sensors, when the only way to show the view through the camera lens was to use a mirror in the body to reflect and image of the scene up into the viewfinder. When you take a picture, the mirror flips up so that the image can then pass to the back of the camera where the film is exposed. The only difference between this old SLR (single lens reflex) design and today’s DSLRs is that the film has been replaced by a digital sensor.

DSLRs like the Nikon D500 have a mirror inside the body to reflect the image up into an optical viewfinder.

Mirrorless cameras have no such mirror. The image passes straight through to the sensor at the back of the camera which passes a live 'feed' to an electronic viewfinder.

Mirrorless cameras take a different approach. They use the ‘live view’ captured by the camera sensor itself to create an electronic viewfinder image. By doing this, they dispense with the need for a mirror and an optical viewfinder altogether.

But what sounds like a win-win situation is a little more complicated than that. Many people prefer the optical viewfinder of a DSLR, mirrorless camera makers have had to develop new autofocus technologies to compete with DSLRs, and mirrorless cameras still can’t compete with DSLRs for battery life and even – in the opinion of many users – simple handling and ergonomics.

Focusing

When mirrorless cameras first became available, the way in which they autofocused was essentially in the same way as a compact camera, a system known as contrast-detect AF. This uses the main image sensor to measure the point at which contrast is highest as a lens moves through its focusing range, and as this is the same sensor that ends up capturing the image, the method is very precise: what you see is what you get.

But it’s also quite inefficient. In effect, the camera has to focus to and fro until it zeros in on the focus distance that gives the sharpest image. Compact cameras have much smaller lenses with lighter internal elements, and these can move efficiently when focusing. Mirrorless cameras have larger sensors and hence larger and heavier lens elements, so this trial-and-error focusing method becomes painfully slow.

DSLRs focus using a different method called phase-detection AF. This is typically much faster than contrast-detect AF because it compares two versions of your subject from two different angles and can quickly determine which way to refocus the lens and by how much. Technically there is the potential for it to be less accurate, as the focusing sensor used to do this is separate from the main image sensor, but it’s certainly fast.

DSLRs use separate dedicated phase detection autofocus sensors mounted behind and below the mirror for viewfinder shooting but switch to on-sensor autofocus for live view on the rear screen.

Mirrorless cameras use the main sensor alone for autofocus both for viewfinder shooting and live view on the rear screen. Many mirrorless sensors now have phase-detection autofocus built in.

Mirrorless cameras can’t use a separate phase-detection sensor because it would obstruct the light reaching the sensor, so for a long time mirrorless cameras couldn’t really compete with DSLRs for autofocus speed. Soon, though, mirrorless camera makers found the answer – they managed to integrate phase-detection autofocus into the camera sensor itself. The latest hybrid mirrorless autofocus systems use phase-detection AF points for speed and contrast AF for precision, and challenge DSLRs for speed.

Canon's sensor-based Dual Pixel CMOS AF system, which works on phase-detect AF, is now found across the company's mirrorless and DSLR lines, and means that models like the EOS M6 (pictured above) can focus very quickly – but the same advantages apply to Canon's DSLRs too.

At the moment, Canon and Nikon have taken slightly different routes in DSLR vs mirrorless technology. For example, the Nikon D850 DSLR uses phase-detection autofocus for viewfinder shooting but contrast AF for its live view mode, whereas the mirrorless Nikon Z 6 has a hybrid on-sensor phase detection system that handles both viewfinder and live view photography – the mirrorless Nikon has a technical advantage.

But Canon uses its on-sensor Dual Pixel CMOS AF phase detection system on both its DSLRs and its mirrorless cameras, so the EOS 5D Mark IV DSLR offers phase detection AF for both viewfinder shooting (via a dedicated sensor) and for live view (via the main sensor). Canon’s mirrorless EOS R and RP cameras use a more sophisticated version of this Dual Pixel CMOS AF system for both viewfinder and live view shooting, but the technical advantage of its mirrorless models over its DSLRs is smaller.

Focusing is only one part of what makes a camera suitable for a particular type of photography, and many sports photographers continue to use DSLRs rather than mirrorless cameras. Even so, mirrorless cameras can now be successfully used for this kind of photography where they would have previously been completely unsuitable.

Viewfinders

The design of mirrorless cameras means they need to use electronic viewfinders. These have improved hugely in a very short space of time, but they still polarise opinion. In the early days their resolution was too low to display a scene with anything like the clarity and detail of an optical viewfinder, and they had so much ‘lag’ when you moved the camera quickly that it was difficult to follow moving subjects.

Early EVFs might have been pretty poor, but the latest and best electronic viewfinders available today have such high resolution that you can hardly see the ‘dots’ and they have a clarity that genuinely approaches optical viewfinders. The new Panasonic Lumix S cameras have the highest EVF resolution yet at over 5 million dots.

Viewfinder lag is less of an issue than it used to be thanks to faster refresh rates, and the most recent area of focus for manufacturers has been in the blackout effect you would typically see when shooting continuous bursts of images. Sony has successfully managed to eliminate this on its A9 model, and Panasonic is now claiming the same for its G9 model .

On top of all this, electronic viewfinders let you view the image with any changes to exposure, white balance, colour settings and so on applied instantly, something optical viewfinder cannot do.

Most electronic viewfinders can also be successfully used to show a more clearly visible view of the scene in low light – very much an underappreciated benefit – and the best examples are clear and largely free from noise in even these conditions.

The 3.6million dot viewfinder inside the Panasonic GH5 was once of the best of its kind but has already been overtaken by the Lumix S1 and S1R.

What's good about optical viewfinders

It’s true that an optical viewfinder does not show a digital rendition of the captured image, but you’ll get to see that on the screen on the back of the camera as soon as you’ve taken the picture anyway.

What’s more, many photographers prefer the ‘naked eye’ view of an optical viewfinder over a digital rendition. It’s a mistake to assume electronic viewfinders are inherently more ‘accurate’ because the display depends not only on the camera settings (which you may change later if you shoot RAW images) but on the quality, contrast ratio and calibration of the viewfinder panel itself. These often display more contrast than the captured image, for example, and can mislead you into correcting exposure settings that don’t need correcting.

DSLR optical viewfinders are still popular because they offer a 'naked eye' view of world with no screen lag or digital artefacts.

Optical viewfinders have themselves become more intelligent. Illuminated LED panels overlaid on the main frame, for example, allow for more information to be visible within them than ever before. This is the principle behind Canon’s Intelligent Viewfinder technology.

The Fujifilm X-Pro2 mirrorless camera (and now the X-Pro3) offers a hybrid viewfinder, one that combines both optical and electronic types. Almost every other mirrorless camera either has no viewfinder (but with the potential to attach one through a hot shoe) or an electronic one.

Optical viewfinders have another key advantage that’s particularly relevant for sports and action photographers. There is unavoidable screen blackout in the camera’s burst shooting mode as the mirror flips up and down between exposures, but this is rarely an issue – the key point is that there is no lag, and it’s much easier to follow a fast-moving subject with a high-speed DSLR like the Nikon D500, for example, than it is with the average mirrorless camera.

Battery life

Even very basic DSLRs will happily offer 600 shots per charge of the battery, but many stretch into four figures. The entry-level Nikon D3500 DSLR, for example, can capture up to 1,550 images on a single charge. The very best pro DSLRs can rattle off almost 4000 frames per charge, although this is admittedly with considerably larger batteries.

Mirrorless cameras, however, fare far less impressively here, with around 350-400 frames per charge being the norm while some are a whole lot less. The Sony A7R III has an extended 650-shot battery life almost double that of its predecessors, so that’s a significant step forwards, but the new Canon EOS RP can only manage 250 shots. Battery life is an issue for mirrorless cameras, but why is this?

As impressive as the flagship Sony A9 is, its battery life of around 480 shots with the viewfinder and approximately 650 with the LCD is significantly lower than what a comparable DSLR offers.

First, mirrorless cameras are inherently more dependent on battery power than DSLRs. Their LCD screens are typically on at all times, and when they’re not it’s the electronic viewfinders that are, and both of these need plenty of power. By contrast, optical viewfinders only need a modest amount for the various LED displays and overlays.

Furthermore, the fact that most manufacturers try to make mirrorless models as small as possible means that their batteries are also small, which also presents a limit on their capacity. Many mirrorless cameras also have image stabilisation built into their bodies, which further degrades battery life (although you’ll also notice battery life to be less impressive when using lens-based image stabilisation on either DSLR or mirrorless cameras).

Cameras like the Sony A6500 can have their batteries charged up through their USB ports.

Of course, you can buy spare batteries for cameras in both camps, so whether this is as great an issue or not is debatable. One advantage of mirrorless cameras, however, is that many now offer charging through their USB ports, like the Sony A6400, which is very convenient when travelling.

Size

The most often claimed advantage of mirrorless systems is that they are much smaller than DSLRs. While image processing and sensor technologies vary across DSLRs and mirrorless cameras, the fact that many mirrorless models use the same APS-C and full-frame sensors that you’ll find in DSLRs means that neither system has any inherent advantage when it comes to image quality. Indeed, this is the main sell of the system: the same size of sensor and image quality as offered by a DSLR without the bulk.

The Canon EOS M50, for example, has the same sensor and technology as Canon’s equivalent DSLRs but is a fraction of the size.

The main reason for this is that DSLRs have a mirror just behind the lens mount and an optical viewfinder mounted above it, whereas mirrorless cameras do not. On entry-level DSLRs with ‘pentamirror’ designs like the Nikon D3500, this doesn’t have a major effect on weight, but more advanced DSLRs with a glass prism in their viewfinder chamber are heavier.

Enthusiast and professional DSLRs are typically designed with glass pentaprism viewfinders, which are heavier than the pentamirror types found in cheaper DSLRs.

There are often trade-offs in making a mirrorless camera body so compact, such as the size of the sensor and battery life, together with the way a camera handles with larger lenses, and how many external controls can be fitted.

Some mirrorless cameras fashioned like smaller versions of a DSLR while others have a smaller rectangular ‘rangefinder’ shape. These are often designed for novice camera users or smartphone upgraders more used to touch control than physical knobs and dials, so a simplified exterior won’t bother them. The Olympus PEN E-PL9 is typical of small mirrorless cameras designed for this new type of user.

Many mirrorless cameras have a small grip fashioned to their front plates, rather than the more substantial ones found on most DSLRs

Small bodies also means small controls, and users with larger hands may not find those on some mirrorless bodies to be comfortable. This extends to touchscreens too, with virtual buttons and controls often too small for then to be keyed comfortably, so although the Nikon D850 DSLR seems huge in comparison to full frame mirrorless camera, many of its pro users will prefer its size because it makes it much easier to see and change camera settings – and because it balances better with big lenses, which is what we cover in the next section.

Canon's most junior mirrorless camera, the EOS M100, has few physical controls, which means that you're likely to be relying on its LCD screen for many tasks.

Lenses

Anyone that opts for a Canon EOS DSLR today has 30 years’ worth of native optics to choose from, and many more when you factor in compatible third-party options. Nikon and Pentax users are arguably catered for even better, with their respective systems happily accepting lenses from even older models without adapters (albeit with some limitations). This is especially true for full-frame DSLRs like the Canon EOS 6D II, Nikon D850 and Pentax K-1 Mark II.

Mirrorless camera makers have not traditionally had this kind of head-start, though it hasn’t taken Sony long to assemble an impressive range of lenses for its full-frame FE mount mirrorless cameras, and Panasonic has been smart enough enter into an L-Mount Alliance with Sigma and Leica to ensure that it will have over 40 native full frame lenses for its new Panasonic S cameras by the end of 2020.

Nikon and Canon have been especially clever with their new full frame mirrorless cameras. The Nikon Z 6 and Z 7 have a small but growing range of native lenses, but you can also get an FTZ mount adaptor for using any of Nikon’s current DSLR lenses without restriction. Canon has also launched lens adaptors for its new EOS R and EOS RP full frame mirrorless cameras, opening up its entire range of EF DSLR lenses to these cameras.

Panasonic's healthy range of lenses for its mirrorless cameras is joined by further compatible options from the likes of Olympus, Sigma and Samyang

Fujifilm and Olympus have also had time to develop their own native lens systems, to the degree that none of the mirrorless camera brands (once the Panasonic S system has caught up) is at any real disadvantage regarding lens choice.

Manufacturers strive to produce the most compact lenses possible for their mirrorless cameras, which this 'body cap' lens from Olympus being the most extreme example.

But are mirrorless lenses really smaller?

This is where the mirrorless bubble is in most danger of bursting. Mirrorless camera makers can indeed demonstrate that their camera bodies are a lot smaller than their DSLR counterparts, but the same can’t be said for their lenses.

Sony's new FE 135mm f/1.8 G Master lens demonstrates that lens size doesn't depend on DSLR vs mirrorless designs and that the best lenses are often big and bulky regardless.

It’s an uncomfortable fact that it’s the sensor size that largely determines the size of the lenses that go with it. Some mirrorless makers have produced small or retracting lenses that do offer a size saving, but these come with other compromises, and when lens makers produce mirrorless lenses to match the specifications and performance of DSLR lenses, they end up pretty much the same size.

This not only undermines the ‘mirrorless is smaller’ argument, it produces handling issues with certain camera-lens combinations. Sony’s A7-series camera bodies are remarkably small, but many of its lenses – especially its top-quality G Master lenses – are unexpectedly big. You might find yourself buying a battery grip for your mirrorless camera just to make it handle better with your favourite lenses.

Video

This is where mirrorless cameras have a considerable advantage, and for two main reasons. First, their design makes them much better suited to the constant ‘live view’ required for video capture. Second, this is where camera makers are concentrating their video capture technologies and where you’re going to get the best video features and performance.

DSLRs can shoot video too

In fact, this is where mainstream video with regular interchangeable lens cameras began. The Nikon D90 brought HD video to the consumer market, and the Canon EOS 5D II brought DSLRs into the professional videography and film-making arena.

For today’s DSLRs, video capture is a standard feature, and the Nikon D5, D850 and Canon EOS 5D IV offer 4K video capture easily good enough for all but the most demanding professional use. Pro film-makers will gravitate towards professional camcorders and cinema cameras, but interchangeable lens ‘still’ cameras are pushing further and further into their territory.

Don't assume DSLRs can't shoot video – the Canon EOS 5D IV is actually pretty good at it.

The problem for the DSLR design, though, is that video capture is a bit of an unnatural act. It means locking up the mirror and exposing the sensor continuously in a way these cameras were never designed to do. It’s not a problem in itself since mirrorless cameras do this all the time anyway, but this mirror lock-up is a bit of a mechanical kludge.

Worse, DSLRs autofocus systems have traditionally been geared up towards viewfinder shooting using separate phase-detection AF sensors. These are disabled during live view/video shooting, and while Canon has developed an on-sensor Dual Pixel CMOS AF system for both its DSLR and mirrorless cameras, Nikon DSLRs still rely on relatively slow contrast autofocus in live view/video mode.

But mirrorless cameras are better

DSLRs can shoot great video that’s fine for commercial photographers working for clients who’ve started asking for this alongside still images. But mirrorless camera makers have had years to develop on-sensor autofocus systems superior to those in DSLRs, and this is where most of the video development effort seems to be concentrated.

Mainstream mirrorless cameras are now getting very good indeed at video, and the all-purpose Fujifilm X-T3 can now challenge dedicated video cameras.

Sony has led the way with high-quality ‘oversampled’ 4K video in its full-frame mirrorless A7-series cameras like the A7 III, and Fujifilm and Panasonic now have cameras capable of capturing 4K video at 60/50fps for smooth 2x slow motion effects in the Fujifilm X-T3 and Panasonic GH5 and GH5S.

If you only need video occasionally a DSLR will be fine, but if you need to shoot it as an important (or the most important) part of your work, then mirrorless is the way to go. It’s not just the cameras – mirrorless lenses increasingly feature high-tech focus actuators and silent stepping motor autofocus technology for smooth and silent focus transitions when filming; the majority of DSLR lenses were designed at a time when this wasn’t even imagined.

The final word

For some people, it’s the availability of one or two features that are crucial to their shooting that pushes them to a mirrorless system. There are far too many to go into here, but even if we just focus on one, namely the silent shutter, we can see what kind of a practical difference this can make.

Anyone frequently shooting in conditions where discretion is key will appreciate a camera’s ability to shoot silently, not just quietly. DSLRs may offer ‘quiet’ or ‘silent’ shutters, but these simply damp or delay the mechanical sound and can’t eliminate it. Having said that, the Nikon D850 offers a genuinely silent live view mode – it’s not just mirrorless cameras that can do this.

In some instances, the technologies that camera makers have had to develop for mirrorless cameras can also benefit DSLRs. The Dual Pixel CMOS AF in Canon DSLRs like the EOS 5D IV and EOS 80D is one example, and the silent shutter mode in the Nikon D850 is another. The Canon EOS 90D and Nikon D780 show that DSLRs can simply be mirrorless cameras with a mirror!

Most mirrorless cameras still depend on mechanical shutters, even if they don’t need mirrors. At the moment, ‘electronic’ shutters don’t capture the whole sensor fast enough to capture fast-moving subjects, so although they offer super-fast shutter speeds for wide apertures on bright days, they’re no good for moving subjects.

Nikon's Quiet shutter 'Q' option is accessed through the release mode dial, but the D850 can also shoot in silence.

The D850's silent shutter option makes it perfect for wedding, social and event photography.

When to choose a DSLR

Mirrorless camera zealots will argue, but the fact is that this is not a one-way fight. DSLRs have disadvantages, but they have advantages too. They’re bigger, fatter, chunkier and more ‘grippable’. They handle better with bigger lenses (and lenses are getting bigger, year by year) and they have more space for external controls, so you spend less time navigating digital interfaces, tapping at touchscreens (try that when they’re damp with mist or rain or you’re wearing gloves) and their batteries last all day instead of just the morning.

They also have optical viewfinders. Mirrorless users might not care, but DSLR fans would never swap the ‘naked eye’ viewfinder image of a DSLR for a digital simulation, no matter how good.

There’s another thing. If you’re on a tight budget you’ll have to work hard to find a mirrorless camera with a viewfinder for the same price as a DSLR – and all DSLRs have viewfinders. Actually, we’ll go further. You will struggle to get a mirrorless APS-C camera with a viewfinder for the same prices as a Nikon D3500 or a Canon EOS 2000D. Except for the Sony A6000, but that’s a five-year-old camera.

DSLRs are still a great choice if you like your cameras big, chunky and physical. They can do video too, but if that’s your main interest then probably you should be looking at a mirrorless camera instead.

Many wished for a full-frame Pentax DSLR for some time - and the K-1 and K-1 II did not disappoint.

When to choose mirrorless

Mirrorless camera bodies are smaller and, if you choose carefully, you can get smaller lenses to go with them – though this only really holds water with the Micro Four Thirds format, as APS-C mirrorless cameras come with lenses as large as their DSLR counterparts.

If you’re an Instagramer, influencer, blogger or blogger, a mirrorless camera like the Olympus PEN-EPL9 or Canon EOS M50 is perfect. They’re small, light and adaptable and have tilting/vari-angle screens that let you shoot from all sorts of angles. They’re great for both video and stills and can easily fit in an everyday bag.

If you’re a pro or semi-pro videographer, mirrorless is the way to go here, too. This is where all the video development in cameras, lenses, hardware and accessories is happening with cameras like the Nikon Z 6 and Sony A7 III.

But if you’re a regular stills photographer who occasionally dabbles in video, the choice is tougher and you have to decide for yourself which you prefer. The market is heading towards mirrorless, but DSLRs are still popular, and there are plenty of people out there who would like this resilient and adaptable old camera design to keep on going for ever.

DSLRs aren’t done. Mirrorless cameras might be the future, but the future isn’t here yet, and for now the DSLR design still does a few things brilliantly where mirrorless cameras are still playing catch-up.