It has been interesting to follow how since last year, there has been several articles published that discuss the “mirrorless camera hype”, and put forward various kinds of criticism of either this technology, or related camera industry strategies. One repeated criticism is rooted to the fact that many professional (and enthusiast) photographers still find a typical DSLR camera body to work better for their needs than a mirrorless one. There are at least three main differences: a mirrorless interchangeable camera body is typically smaller than a DSLR, the battery life is weaker, and the image from an electronic viewfinder and/or LCD back screen offers a less realistic image than a traditional optical viewfinder in a (D)SLR camera.
The industry critiques appear to be focused on worries that as the digital camera market as a whole is going down, the big companies like Canon and Nikon are directing their product development resources for putting out mirrorless camera bodies with new lens mounts, and new lenses for these systems, rather than evolving their existing product lines in DSLR markets. Many seem to think that this is bad business sense, since large populations of professionals and photography enthusiasts are deeply invested in these more traditional ecosystems, and lack of progress in them means that there is not enough incentive to upgrade and invest, for all of those who remain in those parts of the market.
There might be some truth in both lines of argumentation – yet, they are also not the whole story. It is true that Sony, with their α7, α7R and α7S lines of cameras have stolen much of the momentum that could had been strong for Canon and Nikon, if they would had invested into mirrorless technologies earlier. Currently, the full frame systems like Canon EOS R, or Nikon Z6 & Z7, are apparently not selling very strongly. In early May of this year, for example, it was publicised how Sony α7 III sold more units in Japan at least than the Canon and Nikon full frame mirrorless systems combined (see: https://www.dpreview.com/news/3587145682/sony-a7-iii-sales-beat-combined-efforts-of-canon-and-nikon-in-japan ). Some are ready to declare Canon and Nikon’s efforts as dead on arrival, but both companies have claimed to be strategically committed into their new mirrorless systems, developing and launching lenses that are necessary for their future growth. Overall though, both Canon and Nikon are producing and selling much more digital cameras than Sony, even while their sales numbers have been declining (in Japan at least, Fujifilm was interestingly the big winner in year-over-year analysis; see: https://www.canonrumors.com/latest-sales-data-shows-canon-maintains-big-marketshare-lead-in-japan-for-the-year/ ).
From a photographer perspective, the first mentioned concerns might be the more crucial than the business ones, though. Are mirrorless cameras actually worse than comparable DSLR cameras?
There is the curious quality when you move from a large (D)SLR body into using a typical mirrorless: the small camera can feel a bit like a toy, the handling is different, and using the electronic viewfinder and LCD screen can produce flashbacks of compact, point-and-shoot cameras of earlier years. In terms of pure image quality and feature sets, the mirrorless cameras are already equals to DSLRs, and in some areas have arguably moved already beyond most of them. There are multiple reasons for this, and the primary relates to the intimate link there is between the light sensor, image processor and viewfinder in mirrorless cameras. As a photographer you are not looking at a reflection of light coming from the lens through an alternative route into the optical viewfinder – you are looking at the image that is produced from the actual, real-time data that the sensor and image processor are “seeing”. The mechanical construction of mirrorless cameras can be made simpler, and when the mirror is removed, the entire lens system can be moved closer to the image sensor – something that is technically called shorter flange distance. This should allow engineers to design lenses for mirrorless systems that have a large aperture and fast focusing capabilities (you can check out a video, where a Nikon lens engineer explains how this works here: https://www.youtube.com/watch?v=LxT17A40d50 ). The physical dimensions of the camera body in itself can be made small or large, as desired. Nikon Z series cameras are rather sizable, with a conventional “pro camera” style grip (handle); my Canon EOS M50 is diminutive, from the other extreme.
I think that the development of cameras with ever more stronger processors and their machine learning and algorithm-based novel capabilities will push the general direction of photography technology towards various mirrorless systems. Said that, I completely understand the benefits of more traditional DSLRs and why they might feel superior for many photographers at the moment. There has been some rumours (in the Canon space at least, which I am personally mostly following) that new DSLR camera bodies will be released into the upper-enthusiast APS-C / semi-professional DSLR category (search e.g. for “EOS 90D” rumours), so I think that DSLR cameras are by no means dead. There are many ways in which the latest camera technologies can be implemented into mirror-bodies, as well as into the mirrorless ones. The big strategic question of course is that how many different mount and lens ecosystems can be maintained and developed simultaneously. If some of the current mounts will stop getting lenses in the near future, there is at least a market for adapter manufacturers.