Mirrorless vs DSLR: introduction
Go back a few years, and the choice between mirrorless cameras and DSLRs was relatively straightforward. Essentially, if you were either a professional photographer - or had aspirations to be one - and wanted the best of the best when it came to image quality, you plumped for a DSLR. For consumers a bit more concerned with weight and portability, then a mirrorless camera was probably what you'd go for.
Nowadays, you’ve got a harder choice to make. There are very affordable, entry-level DSLRs out there and there are monumentally expensive mirrorless cameras at the high end. How are you supposed to choose?
To rewind a bit, the difference between the two types of camera is in the name. DSLR stands for Digital Single Lens Reflex, and means that once light has passed through the lens, it hits a mirror angled at 45 degrees. The light shoots straight up and into a viewfinder that, when you hold your eye to it, shows you precisely what the lens is seeing at that moment.
It’s a true optical path, with no digital processing in between. When you take a photograph, the angled mirror swings out of the way, revealing an image sensor behind it – it’s why DSLRs make that oh-so-satisfying 'ker-chunk' noise.
A mirrorless camera, unsurprisingly, doesn’t have a mirror. Instead, light goes through the lens, straight onto the sensor, where it is processed and, almost simultaneously, displayed either on the monitor on the back of the camera or on a very small monitor – an Electronic Viewfinder (EVF) on the top. When you push the shutter button, the camera records what’s on the sensor at that moment.
DSLRs use traditional technology which legacy companies like Nikon, Canon and Pentax have decades of experience with. On the whole, DSLRs tend to be robust, capable of great image quality and give you an extremely impressive battery life that the average mirrorless camera just can't match.
Removing the traditional mirror on mirrorless cameras, though, leads to several advantages. Mirrorless cameras don’t need a complicated optical viewfinder or a big mirror to reflect light, which means they can be a lot smaller and lighter. Some jobs, such as autofocus, can be done on the sensor itself, leading to very fast read times that mean some mirrorless cameras are capable of super-quick performance.
These days, there's also a high number of mirrorless cameras with full-frame sensors, too, so at the high end there is no discernible difference between the output of a mirrorless camera and that of a traditional DSLR.
There are other advantages and disadvantages besides, though – read on to find out which you should choose.
1. Size and weight
- DSLR: Traditionally, these were the bigger of the two. This isn't necessarily a negative, as it can help when shooting with big telephoto lenses (and big hands). These days though, mirrorless cameras can be just as large as DSLRs.
- Mirrorless: On the whole, mirrorless cameras are generally smaller and lighter than the average DSLR, making them ideal for travelling light and keeping the overall weight down. You'll find some mirrorless cameras break this "rule" though.
When mirrorless cameras first entered the market, one of their big selling points was their small size. The first cameras of its kind to get really popular were Micro Four Thirds models which traded on the idea that the overall system was much smaller and lighter than the equivalent DSLR system.
As larger sensor sizes started to become popular, it no longer became a simple statement of fact that mirrorless equated smaller. When you use an APS-C or a full-frame sensor, you might be able to get a small(ish) body, but the compatible lenses will likely be big and heavy. Some manufacturers have attempted to answer the problem with retractable or "power-zoom" 'kit' lenses, but as soon as you need to swap to a different type of lens, the problem appears again.
If size and weight is your main concern, Panasonic G series and Olympus cameras have the advantage. They use the Four Thirds sensor format inside its Micro Four Thirds models, which are smaller than APS-C and full-frame sensors. There's an argument that image quality can't match larger sensors - especially in some shooting scenarios such as low light - but the smaller sensor helps to deliver a much more compact system all round.
Some higher-end mirrorless cameras are actually very large, with some manufacturers responding to feedback from photographers who say they would like larger grips for better ergonomics. That even includes cameras like the OM-D E-M1X which has a small sensor and a large body which incorporates two grips.
Panasonic's introduction of its L Mount Alliance full-frame cameras, such as the Lumix S1, are also very large, and are even bigger than some existing DSLRs.
Conversely, entry-level DSLRs are shrinking to compete with the smaller footprint of similarly priced mirrorless cameras. Nikon's D3500 and Canon's EOS Rebel T7 / 2000D are painfully small and light, making them less of a burden to carry around.
- DSLR: There's a huge range of lenses available for DSLRs, as both Canon and Nikon have an optic to suit every job. Pentax also has a lot of bases covered, while options from third-party manufacturers also make for a comprehensive set of compatible options.
- Mirrorless: There are a fewer options for mirrorless cameras, but having been around for a decade or more, most of the bases are covered for older systems. Newer systems such as Canon's R and M mount, Nikon's Z mount, Fujifilm's GFX series and so on have fewer options, but they're growing all the time. Most mirrorless options have at least the basics covered, with the option to use existing DSLR lenses via adapters.
If you want the widest possible choice of lenses, a Canon or Nikon DSLR is possibly your best bet. Each has an extensive range of lenses to suit a range of price points, as well as excellent third-party support from the likes of Sigma and Tamron.
While Canon and Nikon have both had decades to build-up and refine their lens line-up – Nikon's lens mount is unchanged from 1959, for example – the first mirrorless camera only appeared 12 years ago. Mirrorless cameras are, however, certainly gaining ground.
Because Olympus and Panasonic use the same Micro Four Thirds lens mount and have been established the longest, the range of Micro Four Third lenses is the most comprehensive, offering a broad range of optics, from ultra wide-angle zooms to fast prime telephoto lenses.
Fujifilm's lens system is growing all the time, with some lovely prime lenses and excellent fast zoom lenses. Even the 18-55mm 'kit' lens that comes with many of its cameras as standard is very good. There are still a few gaps in the range, but Fujifilm is definitely working hard to deliver a comprehensive, high-quality range of lenses.
Sony offers some really nice high-end optics that are designed for its full-frame line of cameras like the Alpha A7 III, including some specialist optics like the mighty FE 600mm f/4 GM OSS telephoto prime lens too. It now offers a relatively healthy selection for both its APS-C and full-frame cameras.
Both Canon and Nikon have now launched full-frame mirrorless cameras to run alongside each company's DSLR range. At the moment, the dedicated optics for each are a little limited, but many more are promised. Not only that but both Canon and Nikon offer affordable adapters that allow you to use lenses designed for DSLRs (though in some cases, with restrictions).
The most recent change here is the introduction of the L-mount alliance, a venture that unites Panasonic, Sigma and Leica. The three companies have pledged to develop products that can be used in conjunction with those from the other manufacturers, which should help the line to develop quickly. At the moment, there are plenty of lenses available between the three manufacturers, with more appearing all the time.
- DSLR: Many photographers still prefer an 'optical' view for its clarity, natural look and lag-free viewing. These are standard on DSLRs
- Mirrorless: Early electronic viewfinders were low in quality, but recently the tech has improved so much that it's actually a preferable way of shooting for many. You'll get a real-time view of the scene you're shooting, along with vital information displayed easily.
All DSLRs, even the cheapest, come with an optical viewfinder because it's an integral part of the DSLR design. Although it's relatively rare in current line-ups, some entry-level mirrorless cameras, on the other hand, don't have viewfinders at all, so you have to use the rear LCD to compose photos, which doesn't always work so well in bright light.
Mirrorless use electronic rather than optical viewfinders. That means they display the image directly from the sensor readout and not via an optical mirror/pentaprism system.
Electronic viewfinders are advancing at a fast pace, and the latest rarely show any graininess that was an issue in earlier generations, while the visible lag which was also once common has all but been eradicated.
The advantage of electronic viewfinders is that they can display a lot more information than an optical viewfinder, including live image histograms, for example. They can also simulate the digital image the camera will capture, so you don't get any horrible surprises when you review your image as it's exactly what you're seeing.
This simulation is not always perfect, however, and many photographers prefer to see the world with their own eyes as they compose the image and check the digital version on the LCD once it's been captured. They're also easier to use in low light.
This will come down to personal preference; get one of the latest high-end mirrorless cameras with a large magnification, large resolution electronic viewfinder, and you'll be hard pressed to find fault with it. The Sony A7S III is an example of a simply stunning electronic viewfinder, offering superb clarity.
- DSLR: Used to have a clear advantage, but not quite as clear-cut now. On the whole they're better for tracking fast subjects, but can be weak in live view
- Mirrorless: While entry-level models may struggle, many mirrorless cameras now have hybrid contrast- and phase-detect AF systems, which fare much better. Some systems are as reliable as those on DSLRs, if not more so
DSLRs use fast and efficient 'phase-detection' autofocus modules mounted below the mirror in the body. This system can be incredibly fast at focusing and tracking subjects, with cameras like the Nikon D850 and Canon EOS-1D X Mark III offering an incredibly sophisticated system.
The trouble is that these systems only work while the mirror is down. If you're using a DSLR in live view mode, composing a picture or video on the LCD display, the mirror has to be flipped up and the regular AF module is no longer in the light path. Instead, DSLRs have to switch to a slower contrast-detect AF system using the image being captured by the sensor.
Many of the more recent Canon DSLRs (such as the EOS Rebel SL3 / EOS 250D and EOS 6D Mark II), however, include the company's brilliant Dual Pixel CMOS AF that uses phase-detection pixels built into the sensor. This is designed to give faster autofocus in live view mode to close the gap on mirrorless cameras – and it works very well indeed.
Mirrorless cameras have to use sensor-based autofocus all the time. Most are contrast-detect AF based, but these tend to be much faster than equivalent contrast AF modes on DSLRs.
More advanced mirrorless cameras have advanced hybrid AF systems that combine contrast-detect with phase-detect AF from the sensor. The likes of the Fujifilm X-T30, Panasonic Lumix G9, Sony Alpha A7 III and Olympus OM-D E-M1X impress not only with their speed, but also the accuracy with which they can lock on and follow a moving subject. The recently announced Canon EOS R5 has one of the most impressive autofocus systems we've ever seen - so it's clear to see that it's no longer DSLRs which necessarily hold the advantage here, especially if you go higher-end.
5. Continuous shooting
- DSLR: The best DSLRs can no longer match the speeds of the best mirrorless cameras
- Mirrorless: The mirrorless design makes it easier to add high-speed shooting and even cheaper models have relatively fast burst speeds
You need a fast continuous shooting mode to capture action shots, and mirrorless cameras are streaking ahead here, partly because the mirrorless system means there are fewer moving parts and partly because many models are now pushing ahead into 4K video – this demands serious processing power, which helps with continuous shooting too.
To put this in perspective, Canon's top professional DSLR, the EOS-1D X Mark III, can shoot at 16 frames per second when using the viewfinder, but mirrorless cameras like the Panasonic Lumix G9 and Sony Alpha A9 (and the recently refreshed A9 II) can both shoot at a staggering 20fps.
You have to be a little careful though when looking at the spec. Some mirrorless cameras will boast even higher frame rates than this (in some cases, up to 60fps), but will have to use an electronic shutter to achieve this and focus will be fixed from the first shot. Not great if you're planning on tracking a moving subject, or under some types of artificial light where banding can occur without the use of a mechanical shutter.
You've also got to be realistic about what kind of burst shooting speeds you are going to need; shooting at 60fps means you'll fill up a memory card pretty quickly, and you'll have to spend a lot of time trudging through a multitude of images to find that 'one' shot. That said, with even entry-level mirrorless cameras offering faster burst shooting speeds than most DSLRs, mirrorless cameras certainly have the edge if this is your priority.
- DSLR: Once massively popular with pros but have long been overtaken by mirrorless rivals
- Mirrorless: 4K video is now standard on all but the cheapest mirrorless cameras
DSLRs were the first to offer professional HD and Full HD video capture, which together with a vast range of lenses and other accessories, was instantly a hit with pros and video makers.
But the shift has certainly been in mirrorless cameras favor in recent years, offering a wealth of video features that most DSLRs can't match.
4K capture is a more common feature for starters on mirrorless cameras, while DSLRs have been slow to offer this functionality. 4K video capture is almost unheard of in entry-level DSLRs, and only a handful of models further up the chain offer this.
There's also the efficient live view autofocus and processing power offered by mirrorless cameras, while the growing range of adapters and accessories out there offer users a more complete system.
Panasonic has carved out a niche for itself with the Lumix GH5 and Lumix GH5S, offering a hybrid stills/video camera that's loved by enthusiast photographers and professional cinematographers, while Sony has opted for a similar approach with the Alpha A7S III.
Also from Panasonic is its full-frame Lumix S1H camera, one of its full-frame L-Mount Alliance models. We've been told that this has vastly outsold the more stills-oriented S1/S1R models due to its fantastic video credentials, giving you an idea of just how important video is to the company.
- DSLR: Even entry-level models have full manual controls, and DSLRs are powerful cameras
- Mirrorless: They match DSLRs feature for feature, often going a step or two further
In terms of photographic features and controls, DSLRs and mirrorless cameras are hard to split here.
They all offer full manual control over exposure and focusing and can shoot raw files as well as JPEGs, allowing you to get the best image quality possible. In any one sector, such as entry-level cameras, enthusiast or pro models, the control layouts and capabilities are pretty similar. Entry-level DSLRs tend to hide away the manual controls under a layer of automation, but it's the same for mirrorless cameras.
Splitting mirrorless and DSLR cameras in terms of features is getting harder and harder – neither has a monopoly on particular bells and whistles. One thing to watch is that no manufacturer offers lenses that are compatible with both its mirrorless and traditional DSLR cameras – because the back of the lens is so much closer to the sensor on a mirrorless camera, you’ll always need an adapter. That means that even if you have a bag full of decent lenses, you’ll need to spring for an adapter before you can use them on a mirrorless cameras.
One thing you might watch for on mirrorless cameras is improved autofocus zones. DSLRs focus using a separate autofocus module, while mirrorless cameras have their autofocus points on the sensor itself. That means you often get autofocus points that cover much or even all of a mirrorless camera’s sensor, where cheaper DSLRs offer fewer autofocus points. The more autofocus points you have, the more able you are to select the single AF point that best matches your preferred composition.
8. Image quality
- DSLR: DSLRs use APS-C or full-frame sensors.
- Mirrorless: They typically use the same sensors, but there are also smaller formats for even smaller cameras, while there's also some medium-format options, too.
There's nothing to choose here either. Currently, the highest resolution is in a mirrorless camera, the medium format Fujifilm GFX 100, which has a 102MP sensor. Admittedly, that's not a camera many people can afford, although the cheaper Sony A7R IV mirrorless camera manages 61MP - still a good 11MP more than the closest DSLR, the Canon EOS 5DS and 5DS R.
It's not just about megapixels, though, because the main factor in image quality is sensor size. With the exception of medium format sensors, full-frame sensors are the biggest and offer the best quality, while cameras with APS-C sensors are almost just as good and much cheaper – and you can get either of these size sensors in both DSLRs and mirrorless cameras.
But the compact system camera market offers smaller formats too. The Micro Four Thirds format used by Panasonic G series and Olympus is smaller than APS-C, but so are the cameras and lenses, so you need to weigh up what's most important to you - size or ultimate image quality.
Overall, then, there's no intrinsic image quality advantage in a DSLR, given that the same sensor sizes are available in mirrorless cameras too.
9. Battery life
- DSLR: 600-800 shots is average, better models can shoot over 1,000 shots on a charge. Pro DSLRs may offer 2000+ shots per charge
- Mirrorless: Much weaker, typically around 300-400 shots per charge. Some manage around 600 or 700, although those with a higher battery life will often have either very large batteries or require two
Battery life comparisons might not be exciting, but they are important when the differences are as great as this.
The very affordable Canon EOS Rebel SL3 / EOS 250D DSLR, for example, can take 1,070 shots on a single charge, while the Fujifilm X-T4 mirrorless camera, a much more advanced model, match on paper, can only shoot 500 photos before the battery expires. This pattern is repeated across the range of DSLRs and mirrorless cameras.
Why's this? DSLR batteries are sometimes larger, though not always, and you might have thought that driving the mirror up and down for each shot would consume more power, and that that LCD display would be used just as much. However, mirrorless cameras will have to power an EVF in most cases as well.
So, this is one area where DSLRs do often have a substantial practical advantage. If you're somebody that likes to shoot a lot in any given day, then you'll almost certainly need to invest in a second battery, or look for a model which offers USB charging so you can use a power bank while on the go.
- DSLR: The cheapest DSLRs may miss out on some feature like touchscreens and 4K video
- Mirrorless: Cheap mirrorless cameras often have these but don't have viewfinders; those that do cost more.
You might hope that the simpler design of a compact system camera would make them cheaper to buy, but that's not necessarily the case. If you want a fully-featured, 'proper' camera for the least money, then a DSLR is still the cheapest option – but it's getting a lot closer between the two.
For example, the 24MP Nikon D3500 DSLR has a great APS-C sensor, an optical viewfinder (of course), decent manual controls and a staggering 1,550-shot battery life.
Its nearest rivals on price include models such as the Sony Alpha A6000, which packs in an almost identical 24MP APS-C sensor and features a built-in electronic viewfinder. That said, it's only that cheap because it's been superseded.
Once you get into enthusiast and pro market, however, the differences largely disappear – for any given amount of money you get broadly the same features, performance and power.
Mirrorless vs DSLR: the verdict
- DSLR: Sturdy, good value cameras offering old-school handling and top image quality
- Mirrorless: Smaller, technically more advanced and arguably the way forward
While mirrorless cameras are undoubtedly the future, deciding between the two still pretty much depends on your shooting preferences.
If you’re weight sensitive, a mirrorless camera is a great option – screw on a pancake lens and you’ll have a high-performance, larger-sensor camera that barely occupies more space than the compact camera it might be replacing.
If you’re spending under a thousand pounds, you are absolutely spoiled for choice. Modern mirrorless cameras have exceptionally good monitors and reasonably good EVFs even at this price point, so if you’re an old school photographer who can get over that particular hurdle, you’ll find yourself with an incredibly capable camera that easily matches the image quality of its traditional looking brethren.
You will need to be watchful of battery life on mirrorless cameras – there is still a marked difference between mirrorless and DSLR cameras in this respect, and if you’re someone who regularly shoots from dawn to dusk you will want either a mirrorless camera with a battery grip and potentially several spares, or a DSLR.
At the high end, DSLRs mostly have better ergonomics than mirrorless cameras. They’re more bulky, sure, but that bulk is put into chunky handgrips that feel secure almost whatever you’re doing.
The writing isn’t quite on the wall for the DSLR – usability and battery life are still giant ticks in its favor. However, for photographers of nearly every stripe, mirrorless has never been so tempting.