Sony's RX10 is a fixed lens camera that takes very good video. But it's not just any lens: it's a Zeiss zoom with a constant F2.8 aperture. It absolutely defines the camera, and makes this one of the best point and shoot cameras you can buy
So much of what we understand about equipment depends on our definition of "professional". And we also need to split "professional" into two: one for the kit, and one for the person doing the job.
What exactly is a professional then? You could say it's someone who makes their living from what they do. If you're a professional photographer, you pay your mortgage by taking pictures. This definition doesn't in itself say anything about how good you are at your "profession", but you can't be all that bad if you're able to sell enough pictures to pay for your house.
What about "professional" equipment? This used to be easy, but now it isn't any more, because so much new stuff is so good and so - relatively - cheap. All the previous boundaries are being blurred or wiped out. Consumer cameras sometimes contain more advanced technology than professional ones, which remain in that category only by virtue of superior ergonomics and, sometimes, just reputation.
I used to think that a professional was someone who spent about £15,000 ($25,000) - about what a reasonable car costs - on a single piece of equipment. This was a pretty random criterion but it did hold some water until two or three years ago.
Now, the threshold for professional equipment is so blurry as to be almost invisible. And a case in point is the Sony RX10 camera. Ostensibly a consumer product, it has an accessory that lets you connect XLR equipped microphones and has a lens that is so good it should actually be worth much more than the camera itself.
Same size as a small DSLR
The RX10 is not big, but it's around the same size and not completely dissimilar in weight to a small DSLR; some might even be smaller. But it doesn't have interchangeable lenses. For professionals, this could be, and arguably should be, a showstopper. But this is never going to be a professional's first choice for a main camera.
But it might just be a professional's choice for a camera that they have with them at all times.
Virtually every aspect of the RX10 belies its modest but pleasing appearance. We'll come to the camera itself in a minute, but first, that lens. It's a Zeiss zoom lens with a decent range, from mildly wide (24mm) angle to fairly telephoto (200mm). But it's a beauty. There's absolutely no doubt about it: this is a wonderful lens.
It's very sharp at all focal lengths, and has a constant F2.8 aperture, whatever the degree of zoom or wide-angle. So it's a fast lens that's always fast. Lenses like this, which don't get dimmer as they zoom, are rare enough in the world of DSLRs, but in so called "bridge" cameras, well, you can't get such good lenses at the prices people want to pay for what they perceive to be an "inferior" camera format. You would never use the term "inferior" with the RX10.
There is also a very credible argument that says fixed lens cameras can apply all sorts of processing and optimisation to their one and only lens in a way that the can't if they're expected to deal with an unlimited number of lenses of unknown origins and characteristics. This really does make a difference.
Any such preconceptions about the camera's physical format, though, are blown away when you try it. Pictures are extremely sharp and accurate at all zoom levels. And the point is - with a lens this good, why would you want a DSLR, with all the additional expense of buying a whole set of lenses?
Still frame from video, at 200mm showing dynamic range