DSLR vs Mirrorless Cameras

When compared to mirrorless cameras, DSLRs by design have some inherent flaws and limitations. Part of it has to do with the fact that SLR cameras were initially developed for film. When digital evolved, it was treated just like film and was housed in the same mechanical body. Aside from the circuitry required for a digital sensor and other electronics, new digital film media and the back LCD, the rest of the SLR components pretty much stayed the same. The same mechanical mirror, the same pentaprism / optical viewfinder, the same phase detection system for autofocus operation.

While new technological advances eventually led to extending of features of these cameras (in-camera editing, HDR, GPS, WiFi, etc), DSLRs continued to stay bulky for a few reasons. First, the mirror inside DSLR cameras had to be the same in size as the digital sensor, taking up plenty of space. Second, the pentaprism that converts vertical rays to horizontal in the viewfinder also had to match the size of the mirror, making the top portion of DSLRs bulky. Lastly, manufacturers wanted to keep existing lenses compatible with digital cameras, so that the transition from film to digital was not too costly or too limiting for the consumer. This meant that manufacturers also had to keep the “flange distance” (the distance between the camera mount and the film / sensor plane) the same between the two formats. Although smaller APS-C / DX sensors and lenses seemed like a great way to reduce the bulk of DSLR systems, the flange distance / compatibility concerns left them fairly large and heavy physically. 35mm eventually came back with modern full-frame digital sensors, so the mirror and pentaprism sizes again went back to what they were in film days. On one hand, keeping the flange distance the same allowed for maximum compatibility when mounting lenses between film, APS-C and full-frame DSLRs, without the need to re-design and re-market lenses for each format. On the other hand, DSLRs simply could not go beyond their minimum size requirements and the presence of the mirror is what continues to make them so much more complex to build and support.

1) DSLR Camera Limitations

Due to the mirror dependency of DSLRs for “through the lens” (TTL) viewing, they have the following limitations:

1. Size and Bulk: the reflex system needs space for both the mirror and the prism, which means that DSLRs will always have a wider camera body and a protruding top. It also means that the viewfinder must be fixed in the same spot on every DSLR, in-line with the optical axis and digital sensor – basically, there is no other place to put it. As a result, most DSLRs have somewhat similar exterior looks.
2. Weight: large size and bulk also translates to more weight. While most entry-level DSLRs have plastic bodies and internal components to make them lighter, the minimum height and depth issue to house the mirror + pentaprism / pentamirror means lots of wasted space that needs to be covered. In addition, it would be unwise to cover such a large area with a very thin layer of plastic just to make it appear smaller / lighter – the underlying idea of a DSLR is ruggedness, even on a basic body. On top of that, DSLR lenses are typically large and heavy (especially those with a full image circle that were created for 35mm film / full-frame), so a super light camera body would result in balance issues. In essence, it is the larger physical size of DSLR systems that directly affects the weight.
3. Complex Mirror and Shutter Design: every actuation requires the mirror to move up and down to let the light pass through directly onto the sensor. This alone creates a number of issues:
   • Mirror Slap: the most amount of noise you hear on SLR cameras comes from the mirror slapping up and down (the shutter is much quieter in comparison). This mirror slap results in loud noise and camera shake. Although manufacturers have been coming up with creative ways to reduce noise by slowing down the mirror movement (Nikon’s “Quiet” mode for example), it is still quite loud. Camera shake can also become an issue when shooting at long focal lengths and slow shutter speeds. Once again, DSLR manufacturers had to come up with features like “Mirror Lock-Up” and “Exposure Delay” to allow mirror to be lifted, then exposure taken after a set delay – all to reduce vibrations.
   • Movement of Air: as the mirror flips up and down, it moves plenty of air inside the camera chamber. And with air, it also moves dust and other debris around, which eventually ends up on the camera sensor. Some people argue that their DSLR cameras are better suited for changing lenses than mirrorless cameras, because there is a mirror between the sensor and the mount. There might be some truth to that. However, what happens with that dust after the mirror moves inside the chamber? All that dust will obviously circulate inside the chamber. In my experience shooting with a number of different mirrorless cameras, I found them to be actually less prone to dust than any of my DSLRs.
   • Frame Speed Limitation: while the modern mirror and shutter mechanisms are very impressive, they are limited by the physical speed at which the mirror flips up and down. When the Nikon D4 fires at 11 frames per second, the mirror literally goes up and down 11 times within each second, with the shutter opening and closing in between! It has to be a perfect synchronization of both the mirror and the shutter in order for it all to work. Take a look at the below video that shows this in slow motion (skip to 0:39):http://www.youtube.com/watch?v=PLxUuTbiU3E

     Now imagine this process at 15-20 times per second – that’s practically physically impossible to achieve.

   • Expensive to Build and Support: the mirror mechanism is very complex and consists of dozens of different parts. Because of that, it is expensive to build and provide technical support if anything goes wrong. Disassembling a DSLR and replacing internal components can be very time consuming.
4. No Live Preview: when looking through an optical viewfinder, it is impossible to see what the image is actually going to look like. You have to look at the camera meter (which can be fooled in some situations) and adjust the exposure accordingly.
5. Secondary Mirror and Phase Detection Accuracy: you might already know that all DSLR cameras with phase detection autofocus system (more on this below) require a secondary mirror. I wrote about this in detail in my “how phase detection AF works” article. In short, part of the light that reaches the mirror ends up on the smaller secondary mirror that sits at a different angle than the primary mirror. The purpose of the secondary mirror is to pass the incoming light to phase detection sensors that are located on the bottom of the chamber. The problem with the secondary mirror, is that it has to be positioned at a perfect angle and distance for phase detection to work accurately. If there is even a slight deviation, it will result in missed focus. And even worse, the phase detection sensors and the secondary mirror have to stay perfectly parallel to each other. If they don’t, some autofocus points might be accurate, while others will constantly miss focus.
6. Phase Detection and Lens Calibration Issues: the problem with the traditional DSLR phase detection system not only lies with the secondary mirror alignment issues, but also requires lenses to be properly calibrated. It becomes a two way game – precise focus requires perfect angle and distance of the secondary mirror to the phase detection sensors (as explained above), and requires a properly calibrated lens to the body. If you had autofocus accuracy problems with your lenses in the past, you might have had experience sending your gear to the manufacturer. Very often, support techs will ask the lens in question to be sent together with the camera body. If you wondered why before, now you have the answer – there are basically two places where things could potentially go wrong. If the technician adjusts your lens to their standard camera environment and your camera is slightly off, your issues might get even worse after such tuning. That’s why it is best to calibrate both the camera and the lens to resolve those discrepancies.
7. Price: although manufacturers have gotten much more efficient over the years in terms of DSLR production, assembling the mirror mechanism is no easy task. Lots of moving components mean high precision assembly systems, the need for lubrication in areas where metal components rub against each other, etc. In turn, this all results in increased manufacturing costs (although DSLR manufacturers have gotten very efficient in this regard). And it does not stop there – if anything goes wrong with the mirror mechanism, the manufacturer must repair or even potentially replace it, which is a very labor-intensive task.

2) Mirrorless Camera Advantages

With the rise of cameras without a mirror (hence the name “mirrorless”), most manufacturers have already realized that traditional DSLR systems are not going to be the driving force of camera sales in the future. It makes sense from the cost standpoint alone, but if we really look at the current innovation, where are we at with DSLRs? With each iteration of DSLRs, it seems like we are getting closer and closer to hit the wall of innovation. Autofocus performance and accuracy have already pretty much hit the wall. Processors are fast enough to crank HD videos at 60p. Just to keep the word out and sales going, camera manufacturers have been resorting to just re-branding the same camera under a new model name. What else IS there to add? GPS? WiFi? Instant Photo Sharing? More in-camera editing? Those are all great bells and whistles, but are they innovations that will truly drive future sales? I don’t think so.

Mirrorless cameras open up huge opportunities for innovation in the future and solve many of the problems of traditional DSLRs. Let’s go through each point above and discuss additional benefits of mirrorless cameras:

1. Smaller Size / Bulk and Lighter Weight: removing the mirror and the pentaprism frees up a lot of space. This means that mirrorless cameras can be designed to be smaller, less bulky and lighter compared to DSLRs. With a shorter flange distance, the physical size of both the camera and the lens is reduced. This is especially true for APS-C size sensors (full-frame is tougher to address, as discussed further down in the article). No more wasted space, no need for extra ruggedness to give a feel of a bigger camera. Mirrorless cameras can be made much lighter than DSLRs.The rise of smartphones as compact cameras has taught us a very important lesson – convenience, small size and light weight can potentially overpower quality. The point and shoot sales are significantly down, because most people find their smartphones to be “good enough” for those snapshot moments. All smartphone manufacturers are currently pressing hard on camera features, because they want people to think that they are not just getting a phone, but also a great camera in a single compact package. And judging from the sales figures so far, it is clearly working – more and more people are embracing smartphones and leaving their point and shoot cameras behind. Simply put, smaller size and lighter weight in electronics win in today’s economy. We can observe the same trend in many other gadgets – thinner and lighter TVs, tablets instead of laptops, etc.

   Hence, people will naturally go after lighter and more compact, especially if the quality is not compromised.

2. No Mirror Mechanism: no more mirror flipping up and down means a lot of good things:
   • Less Noise: no more mirror slap, just the click of the shutter is all you hear from the camera.
   • Less Camera Shake: unlike the mirror in a DSLR, the shutter by itself does not produce a lot of vibrations, resulting in less camera shake.
   • No Movement of Air: since there is nothing constantly moving inside the camera chamber, dust is less of an issue (at least in my experience).
   • Easier to Clean: and if dust does end up on the sensor, cleaning mirrorless cameras is easier than DSLRs. You do not need a fully charged battery to lock up the mirror – the sensor is exposed once you dismount the lens. In addition, most mirrorless cameras do not have an opening under the mirror to house a phase detection sensor and other components, so there is very little chance for dust to circulate after the chamber + sensor are fully cleaned.
   • Very Fast FPS Speed: having no mirror means that the capture rate (fps) does not have to be limited by the mirror speed. This means that mirrorless cameras could potentially capture images at much faster frame rates than 10-12 FPS we see today, with much less noise.
   • Cheaper to Build and Support: less moving parts translate to lower cost of manufacturing and support for the manufacturer.
3. Live Preview: with mirrorless, you can get a live preview of what you are about to capture – basically “what you see is what you get”. If you messed up White Balance, Saturation or Contrast, you will see it in live preview – whether in the EVF (see below) or the LCD.
4. No Phase Detection / Secondary Mirror Alignment Issues: now that many of the modern mirrorless cameras are shipping with hybrid autofocus systems that utilize both phase and contrast detection autofocus, you do not have to worry about the alignment of phase detection and secondary mirror. On a number of new generation mirrorless cameras, the phase detection sensors are located on the actual sensor, which means that phase detection will never have to be calibrated for distance, since it sits on the same plane as the sensor that captures the image.
5. Price: producing mirrorless cameras is much cheaper than producing DSLRs. As of today, most mirrorless camera manufacturers charge heavy premiums for their camera systems, because their overall costs are high. While the actual manufacturing costs are lower than DSLRs, companies have to spend plenty of R&D money on improving autofocus performance and other technologies like EVF. Plus, since mirrorless cameras are relatively new, companies have to increase their marketing budgets to educate people. Overtime, however, prices of mirrorless cameras will drop to lower levels than even entry-level DSLRs.
6. Electronic Viewfinder: now here comes the biggest strength of mirrorless cameras and the present + future innovation with it. Without a doubt, an EVF has huge advantages over OVF. While the current implementation of EVF might not be as robust and responsive as it should be (see below), it is just a matter of time before manufacturers fix that. Let’s go over some of the key benefits of EVF over OVF:
   • Information Overlay: with OVF, you never get to see more than some basic grids. There is some static information presented in the viewfinder, but it is always fixed and cannot be easily changed. With EVF, you can get any information you want displayed right inside the viewfinder – from live exposure data to histograms. Different warnings could be added, such as a warning for a potentially blurry shot.
   • Live Preview: the same live preview on the LCD can be shown inside the EVF.
   • Image Review: another key feature that you will never get in an OVF is image review. How cool would it be to see the image that you have just captured right inside the viewfinder? With OVF, you are forced to look at the LCD screen, which is a big pain in daylight conditions. People end up buying specialized loupes just to be able to see their LCD screen in daylight! With EVF, you never have to worry about this, since you could use the viewfinder for reviewing images instead.
   • Focus Peaking: a very useful feature that allows one to see what areas of the frame are in focus. Basically, you can nail focus when performing manual focus without having to rely on your eyes. The area that is in focus gets painted with an overlay color of your choice and you can stop exactly where you want it to be. You would never be able to do this with an OVF in a DSLR.
   • No More Viewfinder Coverage Issues: with OVF, you typically get something like 95% viewfinder coverage, especially on lower-end DSLR models. This basically means that what you see in the viewfinder is about 5% smaller than what the camera will capture. With EVF, you no longer have this problem, because it will always be 100% viewfinder coverage, since what you see in the EVF is what the sensor will capture.
   • Much Brighter Display: if the light conditions are poor, you cannot really see much through an OVF. Focusing with OVF in low light is also difficult, because you cannot really tell if the subject is in focus until you take the picture. With EVF, brightness levels can be “normalized”, so that you can see everything as if it was daylight. Some noise might be present, but it is still way better than trying to guess when looking through an OVF.
   • Digital Zoom: this one is by far my most favorite feature! If you have used a Live View mode on your DSLR before, you know how helpful zooming in can be. With most modern DSLRs, you can zoom in to 100% and really nail focus. Well, with mirrorless cameras, this feature can be built right into the viewfinder! So imagine manually focusing with a lens, then zooming in to 100% right inside the viewfinder before you take the picture. A number of mirrorless cameras are already capable of doing this. It goes without saying that an OVF would never be able to zoom like that.
   • Face / Eye Tracking: now we are moving to the coolest part of the EVF technology. Because the EVF shows what actually happens on the sensor, additional technologies for data analysis can be utilized to do very cool things, like face and even eye tracking! I am sure you have seen face tracking on point and shoot cameras, but if you take it a step further, you could have the camera automatically focus on the nearest eye of the person that you are photographing. How cool is that? Sony and a number of other manufacturers are already doing this very efficiently on their cameras!
   • Potentially unlimited focus points: as you already know, most DSLR cameras have a limited number of focus points that are distributed mostly around the center of the frame. While it works out in most situations, what do you do if you need to move the focus point to an extreme border of the frame? The only option is to focus and recompose, but that might not be always desirable, since you are also shifting the plane of focus. In addition, anything away from the center focus point is typically inaccurate and could result in “focus hunting”, where the camera struggles with AF acquisition and goes back and forth continuously. With mirrorless cameras and phase detection sensors placed directly on the imaging sensor, this limitation can be lifted. Contrast-detection is already possible anywhere in the imaging sensor, while on-sensor phase detection will eventually get to the point where focus points will be distributed all over the sensor.
   • Subject Tracking and other Future Data Analysis: if things like face and eye tracking are possible with mirrorless cameras, you can only imagine what camera manufacturers will be able to do in the future. Imaging having a complex tracking system that intelligently combines sensor data with autofocus and uses it to track a given object, or subject in the frame. Even the top of the line DSLR cameras today have challenges with full subject tracking. If you have tried photographing birds in flight with a DSLR, tracking can get challenging, especially when the bird moves out of the focus point area, or when the light conditions are less than ideal. If data is analyzed on a pixel level and there is no real autofocus area to concentrate on, subject tracking could potentially get super advanced with mirrorless cameras.
   • Eye damage: when looking through a viewfinder, one has to be extremely careful about photographing the sun, especially with long focal length lenses. With EVF, the image is projected through the sensor and there is no harm to your eyes.

3) Mirrorless Camera Limitations

We’ve gone over the many advantages of mirrorless cameras over DSLRs. Now let’s talk about some of their current limitations:

1. EVF Lag: some of the current EVF implementations are not very responsive, resulting in considerable lag. While this is certainly a nuisance compared to OVF at the moment, it is a matter of time before that lag is eliminated. The latest EVFs are already much better than what they used to be before. But as EVF technologies evolve, the lag issue will be resolved completely.
2. Continuous Autofocus / Subject Tracking: while contrast detect has already reached very impressive levels on mirrorless cameras, they are still very weak at continuous autofocus performance and subject tracking. This makes them pretty much unusable for wildlife and sports photography at the moment. However, with the rise of hybrid autofocus systems and their continuous development, we will soon start seeing mirrorless cameras with much better continuous autofocus capabilities. One of the reasons why mirrorless cameras have been slow in this department, is because most mirrorless systems are small and not well-suited to handle large telephoto lenses. So manufacturers have not been putting much of their R&D efforts into this specific area. Again, it is a matter of time until this is implemented on mirrorless cameras.
3. Battery Life: another big disadvantage of mirrorless cameras at the moment. Providing power to LCD and EVF continuously takes a toll on the battery life, which is why most mirrorless cameras are rated at about 300 shots per battery charge. DSLRs are much more power efficient in comparison, typically in 800+ shot range per charge. While it is not a huge problem for typical camera use, it could be an issue for someone that travels and has very little access to power. Still, I believe that the battery issue is also something that will significantly improve in the future. Batteries will be more powerful and power-hungry LCD screens will be replaced with OLED and other much more efficient technologies.
4. Red Dot Patterns: due to the very short flange distance, most mirrorless cameras suffer from a “red dot pattern” issue, which becomes clearly visible when shot with the sun in the frame at small apertures. Basically, light rays bounce back and forth between the sensor and the rear lens element, creating grid patterns of red (and sometimes other colors) in images. Unfortunately, there is no way around this limitation on all mirrorless cameras with a short flange distance, as discussed here.
5. Strong EVF Contrast: many EVFs designed today have very strong, “boosted” contrast, similar to what we see on our TVs. As a result, you see a lot of blacks and whites, but very little gray shades (which help to understand how much dynamic range can be captured). While one could look at the histogram overlay in EVF, it is still a nuisance. Manufacturers will have to find ways to make EVFs display images more naturally.

As you can see, the list is rather short and I expect it to get even shorter within the next few years. I believe that all of the above issues are addressable and they will get better with each iteration of mirrorless cameras.

In summary, I would like to say that DSLRs simply have no way to compete with mirrorless in the future. I am not saying that everyone will be switching to smaller and lighter mirrorless cameras soon – no, we are still far from that point. However, it simply does not make sense for manufacturers like Nikon and Canon to continue investing into making DSLRs better, when the technology advantage is clearly with mirrorless. Below is what I believe what Nikon and Canon should do in the near future.

4) Nikon’s Mirrorless Future

Currently, Nikon has three different formats and two mounts:

1. CX – Nikon CX mirrorless mount, cameras with 1″ sensors.
2. DX – Nikon F mount, APS-C sensors.
3. FX – Nikon F mount, 35mm full-frame sensors.

When everyone was going mirrorless, Nikon ended up creating a new mirrorless mount – CX with a small 1″ sensor. While the imaging and autofocus technology of Nikon 1 cameras is good and the overall system is fairly compact, the biggest issue is the small sensor size. With a 1″ sensor (which is much smaller than APS-C) as shown below, the Nikon 1 cameras simply cannot compete with APS-C in image quality, bokeh and dynamic range, just like APS-C cannot compete with full-frame, or full-frame cannot compete with medium format. Simply put, Nikon has a sensor size disadvantage with its CX / Nikon 1 system.

So what is the logical way for Nikon to move into mirrorless? Essentially, Nikon has a couple of choices for DX and FX:

4.1) DX

1. Create a different mirrorless mount for APS-C size sensors: this would essentially kill DX. A while ago when I posted the “why DX has no future” article, I received a number of angry comments from some readers. Well, I still believe that DX has no future in a big DSLR box. To be able to compete with the current APS-C mirrorless market, Nikon needs to create a new mount with a shorter flange distance. This will obviously be very expensive for the company and will take a while to catch up with good lenses. Instead of two mounts, Nikon will have to concentrate on three and phase away DX DSLRs in the future. But if this does not happen and Nikon chooses to keep the flange distance the same, APS-C mirrorless cameras from Nikon will always be at a disadvantage in terms of size and bulk. By creating a new mount for APS-C, Nikon can make smaller / lighter lenses and camera bodies.
2. Keep the F mount, but get rid of the mirror: this is obviously the easiest and the cheapest route, and the one that ensures compatibility with all Nikon F mount lenses. With the mirror gone, APS-C mirrorless cameras could potentially be smaller in height (no pentaprism), but they would obviously have the same depth, since the mount to sensor distance has to stay the same. Camera bodies would potentially look box-like, which is hard to design with good ergonomics. At the same time, larger camera bodies would balance well with larger / longer lenses.
3. Kill DX: if Nikon does not want to develop a separate mount for APS-C or transition it over to a mirrorless with the same flange distance, it also has a choice to kill DX completely and only concentrate on CX and FX formats. This scenario is less likely to happen.

4.2) FX

1. Create a different mirrorless mount for full-frame sensors: basically, Nikon could do the same thing Sony did with their A7 and A7R cameras. This scenario is very unlikely to happen, as it would cripple all existing lens owners. With over 80 million lenses sold so far, Nikon would be shooting themselves in the foot by making a new mirrorless full-frame camera mount. Plus, it would be downright silly to attempt to make smaller full-frame cameras. Sony has moved to a smaller camera body, but they have to make compromises with lenses. It is optically impossible to make full-frame lenses with a full image circle much smaller than what they are today on DSLRs. Sony found a compromise by making lenses slower (f/4 vs f/2.8), so anything faster will result in huge lenses and balance issues. Nikon should stick to keeping the F mount for full-frame, as discussed below.
2. Keep the F mount, but get rid of the mirror: this is most likely what Nikon will end up doing in the future. All current and old Nikkor lenses will continue to work, since the flange distance will be the same. Pro-level FX cameras will still be heavy and bulky for better balance with long lenses, while smaller and lighter FX cameras will also be available for those that worry about weight.

5) Canon’s Mirrorless Future

I believe that Canon is in a slightly better boat than Nikon for moving to mirrorless. First, it has no small-format mount to support like Nikon CX. Second, it has already stepped into the mirrorless market with an APS-C size sensor – the Canon EOS M was its first iteration and the company has been releasing updates, although a bit too late and typically not in the USA. Naturally, Canon might move all of its APS-C EF-S cameras to the M mount. The only thing that will be left is the full-frame EF mount, which will most likely follow the same destiny as Nikon’s F mount, without a mirror but with the same flange distance. This way, Canon will only concentrate on two mounts – EOS M and EF.

6) More Thoughts and Updates in 2017

After publishing the original article, I decided to revisit the topic and add a few more notes, since it is a hot topic of discussion that constantly comes up at PL and other photography sites. Recently, as part of the launch of the X-Pro2, Fuji presented a slide that showed a mirrorless camera on a scale with 2 cans of beer on one side, and a single DSLR on another, with text above stating “Extra 2 cans of 500ml beer”:

Which shows the level of absurdity and ridiculousness the subject of DSLR vs mirrorless is reaching today.

Nikon is obviously not happy with its financial performance, blaming the global state of the economy for not being able to reach its financial forecasts, quarter after quarter, year after year for the past few years now. While that might be one of the reasons for disappointing sales, both Nikon and Canon surely feel threatened by the mirrorless competition, which is moving faster and more aggressively. In a recent video, Nikon also compared its D500 with mirrorless cameras, specifically pointing out the faster and the more reliable AF system, so the rise of mirrorless cameras is definitely something Nikon feels threatened by.

7) Weight and Size Considerations

Having owned and used Nikon DSLRs for close to 10 years now, I relate to DSLRs more than mirrorless cameras: it is a system I can trust, build and expand on. DSLRs satisfy pretty much any kind of photography needs and genres. At the same time, during the past few years I have been shooting more and more with the new generation mirrorless cameras and I can see their appeal as well. One of the advantages of switching to mirrorless we see repeated over and over again, is related to weight and size. The big question is, are mirrorless cameras really that much smaller and lighter than DSLR cameras to make them that much more appealing in comparison? Our very own Bob Vishneski has already addressed this question in his in-depth analysis and his conclusion was that one should not look at size and weight advantages as the main factors when comparing full-frame mirrorless to DSLRs. True, mirrorless cameras are always going to be lighter than their DSLR counterparts – after-all, there are less parts and the cameras have thinner profiles, but the differences are not as significant as one might expect, and those differences are only relevant to camera bodies. Full-frame mirrorless offers zero advantages compared to full-frame DSLRs in lens size and weight! So if you have a bag full of gear, the only area where you can save space and weight is the camera body alone. And once you add a few more batteries to the mirrorless arsenal, those differences will decrease even further.

At launch, Sony’s original message was “lighter and smaller” too, but as of the Sony A7 II and the latest Sony G-series lens announcements, we can clearly see that Sony is no longer heavily pushing weight/size advantages anymore, focusing more on superior handling/ergonomics and delivering professional-quality lenses – the two areas where Sony has been struggling so far. Well, those new G-series lenses are no lighter than their DSLR counterparts, simply because you cannot defeat the laws of optics; after-all, the image circle of the full-frame system is the same on both. While shorter flange distance might allow for specific lens designs that might offer some size and weight advantages, in the grand scheme of things, they are not as significant at the end of the day.

Where mirrorless does in fact offer weight and size considerations, is if we look at smaller APS-C sensors. Sadly, DSLR manufacturers have been very slow at offering compelling lens choices for their APS-C DSLR cameras. For example, if we compare Fujifilm’s lenses to Nikon’s DX lenses, we will see that the former offers far better lens choices that are specifically made for the Fuji X mount, whereas most of Nikon’s DX lenses are slow, consumer-grade zoom lenses, which makes the Nikon DX shooter opt out for the more expensive, bulkier and heavier full-frame / FX lenses. In such situations, mirrorless is the obvious winner, because lenses designed specifically for the smaller sensor are always going to be lighter and more compact. Canon is not better in this regard either – most of Canon’s APS-C lenses are limited to slow zoom lenses as well.

8) APS-C DSLR Future

And this is why I have been saying for years that APS-C DSLRs do not have a future. Without a solid line of APS-C lenses, neither Nikon nor Canon can offer a truly equivalent system to mirrorless. Four years ago, I wrote an article titled “why DX has no future“, in which I argued about this exact point: lack of high-quality glass, leaving DSLRs at a disadvantage in terms of weight and bulk when compared to mirrorless. In between and especially after the Nikon D500 announcement, a number of our readers have questioned my article, saying that I was wrong with my prediction back then. I must admit, I definitely thought that things would happen quicker than they have been, but I am still holding on to my prediction – I believe that APS-C mirrorless will take over APS-C DSLRs in the future. Mirrorless camera manufacturers like Fuji, Olympus, Panasonic and others have been focusing heavily on building lenses specifically for their mounts and the size / bulk advantages are clear: they certainly do offer a large selection of lenses which now surpasses the selection of lenses that both Nikon and Canon offer for their APS-C cameras. And not only in quantity, but also in quality! Nikon and Canon failed to make truly attractive APS-C lenses, focusing much of their efforts in making full-frame lenses instead, and at this point, I believe it is too late for them to catch up. Here, mirrorless already has the undeniable advantage. Why would you choose a Nikon D3300 kit, if you can pick up a Sony A6000 kit for the same price, ending up with a more compact and innovative camera? And this is just the beginning – cameras like the new Sony A6300 will be leading in AF performance and reliability, which DSLRs soon won’t be able to compete with.

While Nikon did indeed do a phenomenal job with the release of the D500, this high-end DX camera only interests a specific niche of photographers who are into sports and wildlife photography (keep in mind that I have predicted this camera back in 2012, as it states in the above-mentioned article, in reference to a D400) – not everyone is interested in spending $2K on an APS-C camera that can shoot 10 fps, when a full-frame DSLR or mirrorless can be bought for less money. DSLR manufacturers successfully continue to sell such gear, because of system superiority – no mirrorless manufacturer today has equivalent super telephoto lens choices.

9) Buying Into a “System”

When we look at the sales data from the past few years, things look pretty confusing – if mirrorless is the future, why do DSLRs still dominate the sales charts globally? In my opinion, there are several reasons for this. First, it takes a while to influence the potential buyer with the message “bigger is not always better”. The word “mirrorless” is relatively new and educating people about its advantages is taking time. Second, people generally resist switching systems due to existing investments. If one already owns a bunch of lenses and accessories, they avoid going through the hassle of selling everything and re-acquiring gear. It is an expensive process both in terms of gear expenditures (selling used gear, especially cameras and accessories, generally does not yield much money to reinvest in an equivalent system from another manufacturer) and time to learn and adapt to new tools. And lastly, before making the move, photographers often assess the camera system as a whole and put deep thoughts into what pros and cons they will have to go through when buying into a new system. That right there is a huge disadvantage of the mirrorless system today: it does not offer the same number of tools, accessories and lenses when compared to DSLRs, which puts off many enthusiasts and professionals from making the jump.

A DSLR shooter has a lot of options. One could start out with portrait photography, then move to macro photography, then perhaps landscapes / architecture and if they ever wanted to, they could also get into wildlife photography; lens choices are there for pretty much every type of photography. The same goes for accessories – chances of finding compatible flash guns, TTL speedlights, triggers and many other accessories are higher for DSLRs than they are for mirrorless cameras, just because they have been out much longer and have been widely accepted as the gold standard among professionals. Because of these system advantages, many photographers have been quite cautious about moving to mirrorless.

But things are changing fast. If a couple of years back mirrorless had a very small selection of lenses, today that list has grown tremendously, covering many photography needs. The biggest holes to fill are still in specialized lenses like tilt/shift and super telephotos, but that will be coming fairly soon, especially once mirrorless catches up in the autofocus department.

10) Mirrorless vs DSLR AF Performance

Speaking of which, if a couple of years back one could laugh at how bad autofocus was on mirrorless cameras, things are changing rapidly today, in favor of mirrorless. Unless DSLR manufacturers find ways to convert optical analog output into digital for further analysis, mirrorless will soon surpass DSLRs in AF performance and especially AF accuracy. How? It is quite simple: data derived directly from the recording medium (camera sensor) cannot be analyzed on a DSLR, because that path is blocked by the mirror and the closed shutter in front of the sensor. Autofocus is performed via the AF module, which receives light / analog image from the secondary mirror, as described in our Phase Detection Autofocus article. In comparison, mirrorless cameras have to see through the camera sensor, which allows information projected on the sensor to be scanned and analyzed before capture. Today, mirrorless cameras have phase-detection sensors built right on the imaging sensor and once that information is combined with exposure and other relevant data, the possibilities are practically endless. We have already seen how effective face recognition can be on mirrorless cameras, and if manufacturers continue to make improvements in that area, soon enough every image you take will be tack sharp, with the camera automatically focusing on the nearest eye of the person. Some cameras are already capable of recording images before the shutter is released, to avoid taking pictures of subjects with their eyes closed, and we have already seen cameras taking a picture at the moment the subject smiles. You cannot have such advanced intelligence on DSLRs, not until light continuously reaches some kind of imaging sensor. Tracking subjects gets easier with advanced analysis of the scene and the camera can even potentially predict subject movement and its direction.

In fact, check out the AF capabilities of the latest Sony A6300 and how it does with capturing fast moving subjects:

With a whopping 425 focus points, the A6300 can analyze a lot of information to accurately focus and track a subject. While this kind of technology has not made its way into other, more advanced / higher-end mirrorless cameras, the A6300 can be looked at as a “test bed” for what we will see in the future. This kind of intelligence will bring superiority of mirrorless cameras over DSLRs rather quickly. It is just a matter of time – we can expect the next iteration of Sony full-frame cameras to have such amazing AF capabilities.

In addition, mirrorless cameras do not have to be restricted in terms of focus point coverage like DSLRs do – focus points can exist all over the sensor, not only allowing the photographer to choose any part of the frame for focusing, but also give the ability for the AF system to utilize more focus points for subject tracking.

11) Battery Life Challenges

Most mirrorless camera manufacturers shot themselves in their feet by trying to make mirrorless smaller and lighter. Because of that, companies like Sony have been recycling the same lightweight batteries that do not have enough capacity to shoot more than a few hundred frames. For mirrorless to truly compete with DSLRs, manufacturers need to start offering cameras with much beefier batteries. Until we see some real advancements in battery technology and power usage, the best thing to do at this point is to increase battery capacity. If battery life can be doubled now, it will surely make mirrorless cameras much more attractive to current DSLR shooters. And if that increases camera size a little, so be it – a lot of DSLR shooters complain about mirrorless cameras being too small for their fingers anyway.

12) Lack of Innovation

If we compare DSLRs to mirrorless cameras in terms of technological advancements, it is clear that DSLRs do not deliver as much innovation anymore. We can perhaps get better resolution, fps, better video features, better AF modules and perhaps more built-in features like WiFi and GPS, but that’s not enough to truly excite the younger generation of photographers. Mirrorless cameras will continue to provide many more features to be excited about, because possibilities are truly endless. A lot can be done with EVFs and sensor output alone. With advanced data analysis, we could soon start seeing sensors capable of delivering practically unlimited dynamic range. What if a camera could capture images continuously, adjusting exposure on different parts of the scene, then stitching all of that information into a single RAW file? No more burned highlights to deal with or harsh shadows to recover! Like I’ve said, endless possibilities.

13) Conclusion – Are We There Yet?

While mirrorless is definitely advancing fast, there are some real issues that still need to be addressed before I can recommend them fully over DSLRs. Better battery life, more reliable autofocus system (particularly for shooting fast and unpredictable action), larger buffer, better lens choices (especially super telephoto), improved / smoother EVFs, WiFi + GPS and better ergonomics are all areas of improvement for mirrorless cameras. The gaps are still there, but they are closing fast. Within the next few years, we should see camera manufacturers offer mirrorless options that can truly compete with modern DSLRs in every way, but it has not happened yet. Developing super telephoto lenses will take some time too, so it will probably be a few more additional years until we see fast 400mm+ prime lenses.

No matter how we look at it, I believe that the clock for DSLRs has already been ticking. Unless Nikon and Canon get into the mirrorless game now, they will lose out heavily later. DSLRs might be selling better than mirrorless today, but the situation will surely change, it is just a matter of time. While both companies currently offer mirrorless systems, neither CX nor EOS M can compete directly with other mirrorless systems on the market today. Plus, both mounts seem to be heavily underdeveloped and more or less abandoned. Canon has been staying away from the US market with its mirrorless updates, whereas Nikon’s foray into the mirrorless world seems to be coming to a halt – the last time the company released a CX lens was two years ago…

I am not suggesting Nikon and Canon to develop new mirrorless mounts. In fact, I believe it would be a mistake now, because they would have to start over with lens development, which they are already pretty late in the game for, as it takes years to develop a solid line of lenses for a new mount. My suggestion would be to start out with a DSLR-like mirrorless camera with the same flange distance as the current mounts. If Nikon and Canon can get their feet into the mirrorless market and invest more time and resources into making solid cameras, they will be able to keep their existing customers for a while and continue enjoying their market dominance. But if they act too slow, they risk of becoming the next Kodaks of the photography world.

What do you think about this? Please share your thoughts below!