Earlier today I read a comment by someone who understands the appeal of small, cropped-sensor mirrorless cameras but wondered, “What’s the charm that gets people excited about FF mirrorless?” The writer pointed out that size/weight advantages of mirrorless are diminished in full-frame mirrorless cameras, where one would likely use larger lenses, and that the electronic viewfinder (EVF) displays and shorter battery life seem like disadvantages by comparison to full frame DSLRs.
The answers to somewhat complex and subjective. I provided a rather short answer to the question in the original venue… but only after writing and deleting a longer reply (too long for that forum) that now forms the basis of what follows.
You are right to note that mirrorless (and DSLR) systems both have pluses and minuses. Reading what some write about this subject, you might start to think that the distinctions are black and white, where A is always better — unless the writer prefers B, in which B is always better in every way.
It is actually more nuanced than that, and we are in a period of transition where mirrorless systems are changing faster than DSLR systems — meaning that the former may not yet be up to speed in some areas for some users, but that they are rapidly becoming more competent and may be the better choice for more photographers than in the past.
(I use both mirrorless and DSLR systems. In some cases I prefer my mirrorless system. In other cases I prefer my DSLR. Other photographers I know feel differently. For example, I prefer my mirrorless system for street photography, but I often find myself with folks using small DSLRs. I’ve stood side-by-side with photographers using mirrorless cameras to photograph birds in flight while I used a DSLR.)
Part of the answer involves how the mirrorless cameras became popular, and part of it relates to the features and characteristics of the two options.
While there have been good non-DSLR digital cameras for some time, until Sony entered the mirrorless market there was no popular and successful full frame mirrorless system. Sony made a brilliant marketing move — after their (credible) DSLR efforts showed little potential for overcoming the dominance of Canon and Nikon DSLRs, Sony pivoted, zigged instead of zagged, let the DSLR market go, and attacked with a very interesting mirrorless alternative.
Part of its appeal was the small size and weight of the Sony mirrorless bodies, but there were other important factors at work, too. At a time when existing high-end full-frame systems from Canon had just more than 20MP sensors, Sony almost doubled that with 36MP sensors that they manufactured. If you were a Canon user whose photography might benefit substantially from higher sensor resolution and you had been waiting for Canon to provide it, that Sony development got your attention.
The 36MP sensor was available in a Sony mirrorless body and in a Nikon DSLR. The Nikon D800 (and then D810) made Nikon users justifiably happy, (A friend who had long used medium format picked one of these Nikon bodies up for use in Antarctica, where he was teaching workshops, since it kept the weight down and produced excellent image quality.)
But it was the Sony camera that got a lot of attention from folks who had been shooting Canon. The reasons were pretty simple. Sony was brilliant to make their camera compatible, via adapters, with Canon lenses. While very few Canon users were about to switch to Nikon (and replace all their lenses!), it was a much easier “sell” to Canon users, who only had to invest in a higher MP body plus an adapter, with the promise that their current lenses would work.
(A few caveats… Sony was slow to introduce their own lenses, and Sony switchers had little choice but to use third-party lenses with adapters. The early performance of adapted lenses from Canon was a mixed bag — some worked OK but others were less satisfactory or not compatible. Today that situation has changed as more of the compatibility issues have been improved and as Sony has introduced more if its own lenses.)
Early on, the main reason that folks tried the Sony mirrorless system was usually because of the higher MP sensor. At that time I heard very few people say, “I want to try this because it does away with the DSLR mirror.” I heard quite a few say, “I’d like to use that 36MP sensor!” I also heard many concerns about performance issues common to adapted lenses and mirrorless cameras of that era.
The Sony sensor proved to be state of the art in another way — it produced more dynamic range and lower noise and worked well at higher ISOs. These were pluses for photographers who regarded these as important issues.
(Here, subsequent developments represent a sort of inverse of what happened with lenses. With lenses Sony “got by” at despite some serous challenges and has more recently resolved many of them. With the sensor DR issue, Sony started with the biggest advantage that it had, but the advantage declined over time, to the point that it is now much less significant.)
And, of course, over time Sony continued to work at improving and perfecting their designs in a number of other ways that I won’t detail here.
What about the more general questions about the appeal of and prospects for mirrorless cameras, especially full frame models?
Mirrorless bodies can be considerably smaller and lighter than comparable DSLRs by foregoing the pentaprism and swinging mirror. They also reduce the number of mechanical components in this system, with some potential advantages in manufacturing costs, reliability, and speed.
There are plenty of obvious examples of the decrease in size. One of my favorites is there relatively tiny size of the miniMF Hasselblad X1D-50C camera compared to, say, the Pentax 645z. Another is the comparison between the Sony A7r cameras and full size DSLRs.
However, while the reduction in camera size is significant, if you use the same or comparable lenses your overall percentage weight/bulk reduction is not quite so substantial. You can use small lenses on a DSLR, and big lenses are still just as big on a mirrorless camera! If you tend toward mainly shooting with a small prime or two, the advantage is greatest, but if you tend to use bigger lenses, such as the large aperture zooms, especially longer ones, the advantage overall is smaller. Each photographer will look at this differently.
Mirrorless systems have some other advantages. While not everyone likes their electronic viewfinder (EVF) displays, they can offer types of useful information that are less available or not available at all in typical optical viewfinders. They also can work exceptionally well in very low light by means of exposure simulation. The electronic viewfinder may give you a decent display in near darkness where it would be very difficult to see the subject in an optical DSLR display. Some specialized manual focusing aids are available on mirrorless systems that aren’t present on DSLRs.
One of the issues for mirrorless systems has been system latency — a combination of electronic display latency and latencies in the system between the time you press the shutter release and the time the exposure is made.
A EVF display can never provide a truly real-time image. There is always going to be some delay as light is converted to electricity, the electronic signal is converted to data, the data are moved around inside the camera, and then as the data are used to drive a display, where the electronic image is constructed line-by-line. Current cameras are much, much faster, but some latency will always exist.
Initially, because of the very different ways they operated, mirrorless autofocus (AF) systems also introduced significant delays. This has improved a great deal over time, to the point that some of the best of mirrorless AF systems are as good as DSLR AF systems in some circumstances, though few photographers are choosing mirrorless over DSLRs yet for photography where very quick AF is critical.
On the other hand, mirrorless systems have the potential to reduce mechanical latency. DSLRs physically move, with exquisitely precise timing, a mirror system and then a mechanical shutter. A purely electronic system has the potential to eliminate this source of DSLR latency.
Early on latency was crippling problem. Back in about 2000 I had what was then regarded as a basic state-of-the-art mirrorless camera, the Canon Pro 1. The operation of the camera was decidedly leisurely — the image in the display clearly lagged well behind its real-world source, AF was a very slow process, there was a big black out when the shutter was released, and there was a notable delay after pressing the shutter release. For what it was, in its day, the camera could produce decent images — but it was useless for any sort of active subject.
Current mirrorless systems have made tremendous progress from this modest starting point. For most photography today, most mirrorless cameras will not leave the photographer feeling that they have to wait for the camera to catch up in many situations. For a lot of photography, system latency has already diminished to the point where it is not a major issue.
One other issue has to do with battery power. To generalize, mirrorless cameras may consume batteries at a rate that is roughly similar to that of a DSLR in “live view” mode. Typical DSLRs shooting in the normal mode will get far more shots from a battery. This annoys some folks, and even people I know who love their mirrorless cameras wish that they got more shots before the battery is drained. On the other hand, others point out that getting 360 shots from a battery is like running getting shooting ten rolls of film before needing to stop and reload…
There’s still more to say, but I’ll end here with my own personal, subjective assessment of the relative state of DSLR and mirrorless systems. K
I prefer a DSLR for some of my photography… and I prefer a mirrorless camera for some of my photography. Right now a mirrorless system can be the ideal solution for some photographers, but it isn’t right for everyone. I know quite a few landscape photographers who are using them now — camera latency is rarely and issue for them and they would be using live view with a DSLR anyway — and I prefer a small mirrorless camera for street and travel photography. And in each of the areas where DSLRs used to have a distinct performance advantage over mirrorless, the mirrorless systems have made great strides. We aren’t there yet, but is not crazy to think that continuing mirrorless camera development will eventually lead us to a point where DSLRs fade from use.
G Dan Mitchell is a California photographer and visual opportunist. His book, “California’s Fall Color: A Photographer’s Guide to Autumn in the Sierra” is available from Heyday Books and Amazon.
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