"Does Sony really have the advantage now in full frame mirrorless? Specifically, are they getting all the technology first?"
No and maybe.
There's this strong urge to try to simplify things down to winners and losers, and the fan boys flaming the forums don't make this any easier to decipher.
Let's start with where I think the Sony Alpha models' strengths lay: (1) aggressive sensor technology adaptation; (2) the (slightly) best mirrorless let-the-camera-do-it-all, hands-off autofocus [that's not the same thing as "best autofocus"]; (3) the A9's no blackout EVF; and (4) getting to mirrorless before Canon and Nikon. Actually, #4 is probably the most important of the four. Nikon isn't far behind with #1 and #2, and #3 is really a cost decision as much as anything else; the technology is known and available to all.
Sony's weaknesses have been in areas where they still need to play catch up to the DSLR Duo: file size and handling, ergonomics, menu organization, weather sealing, and more. Surprisingly, I see better and more flexible 4K video from Nikon and Panasonic off the same sensor Sony uses, too.
The point of the last two paragraphs is simple: Sony may be one of the leaders in mirrorless sales, but there are still many things that they need to improve in their products. I'm impressed at how much Panasonic got right in their full frame cameras, and at how well Nikon did out of the box with their serious mirrorless endeavor (the Z6/Z7 twins). Canon still seems to have been less focused and is still casting about, though rumors and the just pre-announced R5 suggest this is about to change.
Thing is, every mirrorless camera maker has a different To Do List they need to aggressively keep pecking away at. Technology is moving fast, the overall camera market is collapsing fast, market shares are shifting, and the DSLR-to-mirrorless transition is now in full swing. You can't sit still with that much happening. The heart of the digital camera market has changed from a still growing but mature one (2005-2012 DSLR) to a flat, more immature one (post 2017 mirrorless).
I do see Sony as being aggressive on technology. They've been hit-or-miss on that over their corporate history. Sometimes their technology pushes have been right for the time/market, sometimes they haven't been. Often they fail to make the technology truly usable by the customer (pixel shift, anyone?) But I'd guess that any new technology that comes down the pipeline that might improve cameras is going to be jumped on by Sony at this point.
That said, I'm not sure cameras need more cutting edge technology at all. They need to catch up to the current technology (e.g. Wi-Fi 5, 4G, USB-3.1), and they need a lot of polishing of rough edges. If there's to be a true consumer market for cameras in the future—as opposed to just a small number of serious enthusiasts and pros—cameras need to get smarter and simpler to understand and use, too. I don't see those things in Sony's wheelhouse (though admittedly, most of those aren't in anyone's wheelhouse, it appears).
Here's how I tend to watch the companies:
- Canon — I watch them because of their size. They're the biggest player in cameras, have the most to lose, and have the biggest transition to make. So far, what I see is disarray and a lot of poor, contradictory decisions. Still, if anyone manages to preserve the consumer camera market, it's likely to be Canon, so you have to watch to see if they find something that "sticks."
- Fujifilm — I watch them because a lot of their designers and engineers actually take photographs. They also clearly listen to (at least some) photographers. Thus, they tend to make good decisions about what's important to a serious photographer. Corporately, cameras are an ego thing at Fujifilm: last century they made themselves into one of the two biggest players in photography (Kodak was the other), and they'd really like to get back to that position. They won't, but that doesn't make them unimportant.
- Nikon — I watch them because I'm a long time Nikon user and still have mostly Nikon gear. While they don't have the photography-centric staffing that Fujifilm does, Nikon tends to make solid basic decisions. That's because they're top-down, consensus-driven engineers. I personally don't think they have enough true customer interaction or take enough of the right risk, but if you look at what they've done throughout their camera-making history, they've always made strong centric choices. Thus, you might say that I watch Nikon to see where the center of the market really is.
- Olympus — I watch Olympus because they have clever engineers who every now and again think completely outside the box or tackle a problem no one else has thought of. That's given us things like a really strong five-axis IS approach, pixel-shift shooting, live composite shooting, and more. That said, their sensor choice (size) now has boxed them in, the corporate financial scandal put the camera group in real peril at exactly the wrong moment in time, and their Nippon-centric approach, sales, and style is not serving them well globally.
- Panasonic — I watch them because they keep making interesting and good decisions. I originally questioned the GH models due to their size, but they had a secret sauce: serious video cred (and as a serious 4K video camera, they were considered small ;~). Like Fujifilm, you get the sense that Panasonic has a lot of actual photographers and especially videographers in their design/decision teams.
- Sony — I watch them because they start as a strong and leading electronics company, and electronics are now key to cameras. Yes, image sensors are a strong point for them, too, though I'm pretty sure that the division that makes them wants more customers than just Sony Imaging, so will sell them to anyone for the right price. Sony dabbles in a lot of other electronic areas, as well. What Sony hasn't done is to get all their ducks in a row. It wasn't until last year that they even thought to make their smartphone camera team and dedicated camera team work together. I'm not sure that has actually produced anything yet, though you think it would have. Given that Sony is the only one of the camera makers that also makes smartphones, you have to watch Sony to see if they figure out the connection.
Now for the rub: cameras are now just like pretty much every other electronics device. It's the software that's important, not so much the hardware. Unfortunately, I can't say that I'm really watching any of the camera makers to see what state-of-the-art software they can do. Sony's dipped into machine learning with their focus system (as has Olympus), but there are plenty of software issues with their cameras still (what, no lossless compression?).
"Which should I get, the 35mm f/1.8 S or the 50mm f/1.8 S (or maybe even a 35mm and 85mm?)?"
This type of question comes up a lot these days because people are buying basic lenses again due to transitioning to mirrorless. In this case, it's a Nikon Z question, but I've seen Fujifilm, m4/3, and Sony variants of it. In most cases, the questioner only has the budget for one lens, so they ask the "which focal length" question. Particularly of primes.
There's probably a whole lecture/workshop worth of material in answering such questions. Most often this particular type of question comes up with someone shooting event, street, or travel photography. They want a prime for fast aperture and overall optical capability. They speak in singular ("prime" rather than "primes") for multiple reasons: (1) they don't have the money for or don't want to buy multiple lenses; or (2) they realize that putting a prime on the camera is a commitment.
That last word is really, really important when considering a lens, particularly for event or street shooting. Things are happening around you. Using a prime you've basically committed to a focal length (and that's perhaps forcing you towards a certain perspective, too). Whatever happens in front of you, you're going to photograph with the focal length that's on your camera, because if you have to change lenses, you very well may miss the moment you wanted to capture.
Which is one reason why people buy zoom lenses ;~).
When people ask me about a particular focal length versus another, they're usually not talking about how sharp the 35mm is versus the 50mm, for example, even though they sometimes phrase it that way. They're really trying to decide on what to commit to in terms of angle of view and perspective.
I can't actually answer that question for you—again, "should I get the 35mm or the 50mm?"—because my photographic style is different than yours.
So here's a thought: take your zoom out, tape it at one of the focal lengths you're considering and shoot with it for an hour or more. Now tape it at the other focal length and repeat. I'll bet you know the answer to your question now ;~).
"What does mirrorless still need to tackle?"
That's an overly broad question, so I'm going to to isolate it to just the image sensor for now, since that is the key component that enables mirrorless photography. I see several key areas that need addressing:
- Less rolling shutter — the "electronic" shutter of most mirrorless cameras still has a long way to go before it matches what the mechanical shutters do with motion. Completely losing the mechanical shutter is a likely desired goal of the camera makers, as it reduces costs and complexities. But to get there we basically need a global shutter, not just that faster rolling shutter we also haven't yet gotten. Global shutters unfortunately produce extra electronic noise in their current forms, so you'd lose dynamic range capability, which is the opposite of what most of us want.
- Flash with silence — a global shutter would solve the problem here (though see above), but we could also just use better syncing of light output with image sensor timing when an electronic shutter is used to keep the camera silent. That may mean a redesign of how "flash" works, much like we got with things like Nikon's Auto FP flash for DSLRs.
- Two axis phase detect — Olympus does both horizontal and vertical discrimination in their on-sensor phase detect, but that is currently done with fewer actual sensing points. Canon sort of gets this from their dual-pixel approach (all pixels do phase detect, though I think they're all oriented the same). Nikon and Sony are highly sensitive on the long axis, but not very sensitive on the short axis. I suspect we have a ways to go before we get everything out of phase detect on sensor that we can.
- More true monochrome options — Bayer filtration reduces overall resolution due to the demosaic involved, plus less light reaches the photo diodes. Those of us that work in B&W from time to time really want more cameras like the Leica M Monochrom, which drops the Bayer filtration and gives us both benefits out of the same sensor and camera.
Note that I didn't say "more dynamic range" or "more pixels." Frankly, I don't need either at the moment, though I certainly wouldn't reject it if given more. I somehow doubt you need more, either. Right now both DR and pixel count are becoming more about bragging rights than actual need ("my car has a V12...").
