Short version: you're going to be buying new lenses for awhile (don't ask why).
tl;dr version:
We've probably had four, maybe five generations of clear lens optical improvements during my career. These have been triggered by advancements such as glass (e.g. ED, aspherical) and design tools (computerized optical analysis). Functions such as autofocus and VR/IS have also triggered changes in capability.
The introduction of mirrorless generated a forced change: a proliferation of new mounts appeared. 4/3 became m4/3. EF became M and RF. F became XF and Z. A became E. About the only company that didn't roll out a new mount was Pentax, who dabbled with an odd mirrorless camera and then decided there were too many sharks in the water and just went back to their DSLR cabana to rest.
Most of you reading this think one of two things:
- You don't need new lenses for mirrorless because mount adapters exist.
- You only need new lenses for mirrorless because the mount changed.
I've had a ton of experience with all the new mirrorless mounts and the lenses for them, and I'm going to argue that neither of those are the reasons why you should be buying new lenses. Something else changed besides DSLR mounts becoming mirrorless mounts. That something is a different design ethic that resulted in higher quality lenses.
It took Sony awhile to get on board, but Olympus and Nikon have done this from the beginning of their mirrorless endeavors: simply design better lenses. Far better lenses. Lenses with a near complete lack of negative attributes. Canon, unfortunately, seems to be going to take a while to get fully up to speed with this; much like Sony's early E-mount endeavors I'm seeing a mixed bag so far from our market leader.
Part of the removal of negative attributes has to do with in-camera lens corrections (and out-of-camera lens correction profiles). If you don't have to correct optically for linear distortion and vignetting, for instance, suddenly you can optimize for the other components of the optical formula.
About the same time as mirrorless started appearing, other things were happening in the lens business: new glass types, new aspherical molding techniques, new coatings, better ability to control and refine polishing methods, better mechanical alignment procedures, and more.
However, the Big thing that happened was this: the realization of the camera companies that (a) they had to provide an adapter to help grease your transition, however (b) you weren't likely to buy lenses in the new mount unless there was a compelling reason to do so. Well, one compelling reason would be "the new lens is just far better."
These days, that's exactly what I'm finding. Particularly:
- m4/3 — the Olympus/OMDS PRO glass deserves the three-letter suffix. There's not a dud among them. Moreover, most of the ED labeled lenses are also really good, too. That's over two dozen lenses that are solidly state-of-the-art optically in the m4/3 mount.
- Z — Nikon said S stands for Superior, though I think they made that up after people kept asking what the S stands for. But "superior" is indeed what they are. Again, not a dud in the bunch, and Nikon's improved themselves from being really good in lenses to being absolutely great. Already we're nearing two dozen such superior lenses.
- Sony G/GM — the original Zeiss/Sony collaborations weren't nearly as good as one would expect from that first name being involved. But once Sony put their full weight behind G and GM lenses, things changed dramatically. Once again, not a dud in the bunch, and we're over two dozen of such lenses in the full frame mount already (plus half dozen in the APS-C size).
But it's not just the camera makers that are upping their game. Sigma and Tamron are playing along as well with their mirrorless offerings. Moreover, we now have a handful of Chinese companies that are proving to be nimble and decent competitors nibbling on the fringes (mostly with prime lenses). Laowa, TTArtisans, and Viltrox seem to be doing the most consistent job here, but I can count six other Chinese players that are starting to show clear ability to produce at least DSLR-level lenses, if not better.
What do I mean by DSLR-level lenses?
I have to go back a bit in time to put that fully in perspective. Film cameras originally came with prime lenses, even after we got interchangeable lens mounts. The big design goal for much of the early film SLR period was simply correcting for basic aberrations, with a sub-goal of expanding the available focal lengths. As film SLRs developed and gained in popularity, a number of things started to happen with optics. In particular, autofocus and zoom focal ranges added convenience that drove much of the designs in the 70's, 80's, and 90's. The original Tamron 28-200mm lens in the early 90's also started a trend that was much imitated: "good enough" across a wide range of things.
Nikon is the first company that I can document making a change to their optical designs because of the (then) future DSLR era. From conversations with Nikon engineers, that also started in the early 90's, with the eventual 17-35mm f/2.8 lens being the first product that Nikon made that tried to deal with some of the issues they expected to encounter with the always flat, telecentric-needy digital image sensors. Much of Nikon's late 90's through teens lens designs were all about dealing with those issues, as well as aperture and element positions in the lens itself vis-a-vis reflections off the image sensor.
While new DSLR lenses got optically better over the years, I'd argue that most of the design decisions were primarily dealing with unique-to-digital aspects of the optical path. I found a lot of things not being well addressed in the DSLR era: focus shift, field curvature, coma, and so on. Before lens corrections appeared, linear distortion and vignetting absolutely had to be key elements considered in the optical design, which had downstream implications on the other optical design choices.
When I compare a DSLR-era lens with a well-considered mirrorless-era lens, I tend to see the same things (yes, these are generalizations; some exceptions exist):
- The DSLR lens is weaker in acuity/contrast in the corner; DSLR lenses can be exceptional in the center but with a lot of falloff as you move outward to the corners
- The DSLR lens has more field curvature and focus shift (ironically, focus shift was a primary contributor to lower autofocus accuracy)
- The DSLR lens has less physical vignetting and linear distortion
- The DSLR lens has more complex and problematic flare issues
- The DSLR lenses have more sample variation (though that started to go away in the teens)
Something else happened, too. Sigma, for instance, documented that their lens designs benefited when they were able to put high resolution image sensors into their development and alignment processes.
My contention is this: chosen carefully, the mirrorless lens set you deploy today with any of the high-end mirrorless cameras is far more capable of providing you near optimal data than you we had through most of the DSLR era. This is reflected in my gear closet: almost no DSLR lenses are left. The only ones that are tend to be unique optics that haven't appeared in mirrorless yet (e.g. my 19mm PC-E, the 500mm PF). Lens by lens, when I compare the top-end mirrorless one versus the equivalent top-end DSLR one, the DSLR one has lost.
Of course, I'm a technical gearhead with a long-stated preference for optimal data. So you might be quick to dismiss my thoughts here.
Don't be. You might have read all those articles that went viral recently when the head of Sony Semiconductor predicted that smartphones will exceed dedicated camera quality in the next couple of years. Well, here's one reason why he's not right: the smaller you make the lens/sensor system—and smartphones need them to be brutally small—the more you succumb to physics (e.g. diffraction), plus the more difficult it is to make lenses that can resolve what you need. High quality gets more difficult the smaller you try to make the lens.
That's one of the things that's impressive about Olympus's (and now OMDS's) PRO optics: they're dealing with a smaller capture area and far higher tolerance and acuity needs than full frame, but they've created a full lens set that stands up to that. It's also the reason why full frame is the "hot" format: 24x36mm is a big enough capture area that it's easier to design high-end optics for, but not too big that it becomes completely un-economical for consumers.
And that brings me to this: the Japanese camera companies know that dedicated cameras have to move upscale, and moving upscale means that they have to do more than just make better cameras, they also have to produce even better optics than before. They have no choice. The "good enough" and "make believe*" smartphone train has a full head of steam behind it and is capturing most of the world's images these days. As I predicted 15 years ago, the camera companies simply have to move upscale and cater to a smaller, but highly demanding, market.
So yes, if you're still buying cameras, you're going to be buying lenses. I know I am.
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*What do I mean by "make believe"? I mean that pixel values are guessed at by algorithmic AI. Oh, is that a face, then let's just put some nice facial tone pixels in there. The question that raises is whether or not people can tell a real pixel from a made-up one. We're still in an era where the observant can. Moreover, real pixels scale well, while made-up pixels don't (currently), so that has implications, too.
