When you’re shopping for a camera, you have a million specs and features to consider. Size, weight, battery life, megapixels, zoom power. ... Can you guess which aspect consumers consider most important?

The colour of the body. (“Ooh, I like the shiny red one!”). The camera buyer for a national electronics chain told me that. We both slapped our foreheads. Please. If you’re buying a camera, shouldn’t picture quality be the most important detail?

If so, what you should care most about is the flat, rectangular light sensor inside the “film.” In general, the bigger the sensor, the happier you’ll be with the results and the more you’ll pay.At the low end, snapshot cameras with tiny sensors (0.4 inches diagonal) cost $150 (Rs 8,141) but give you blurry, grainy low-light shots. At the high end, those professional, big, black SLR cameras cost $2,000 (Rs 1,08,559) to $6,000 (Rs 3,25,679) but come with full-frame sensors. That is, these sensors are as big as an old piece of 35 mm film (1.7 inches). They deliver unparalleled low-light quality, richness of colour, detail and soft-focused backgrounds.(You can buy cameras with even bigger sensors – medium-format cameras that cost $20,000 (Rs 10,85,599) and military cameras that cost millions – but let’s say you live in the real world.)

All of this explains why Sony’s 2013 camera/camcorder lineup is so startling. The company has put full-frame sensors into three new cameras, at prices and body sizes that nobody has ever attained. For example, there’s the A99, which Sony says is the world’s smallest and lightest full-frame SLR. It’s meant to compete with professional cameras like the Canon 5D Mark III ($3,200 or Rs 1,73,695) and Nikon D800 ($3,000 or Rs 1,62,839) – for $2,800 (Rs 1,51,983). (These prices are for the bodies only.)

The A99 is sort of homely, but it has a long list of distinguishing features: fast, continuous focusing, even while filming or shooting something running at you; two memory-card slots; built-in GPS function that stamps every photo with your location; 1080p, 60-frames-a-second high-definition video; microphone and headphone jacks; and an electronic viewfinder whose video shows you the results of your adjustments in real time.

Sony says the A99 is also the only full-frame camera with a screen that flips out and tilts.Then there’s the VG900, Sony’s first full-frame camcorder. It costs $3,300 (Rs 1,79,123)  – about $10,000 (Rs 5,42,799)  less than any other full-frame camcorder, Sony says. And its sensor is about 45 times as big as a standard camcorder’s sensor.

Now, a huge sensor may not seem to make sense in a camcorder. One frame of hi-def video has only about 2 megapixels of resolution; what’s the point of stuffing a 24-megapixel sensor into the camcorder?

Answer: It’s about picture quality. A big sensor gives you amazing low-light video, gorgeous blurry backgrounds, greater dynamic range and better color.

Thousands of filmmakers use full-frame SLR still cameras to shoot video, because of the superior quality and because they can use different lenses for different video effects. SLR-based camcorders like Sony’s VG900 offer the same features in a camcorder shape. They’re much more comfortable to hold, and their buttons are better placed for video operation.The VG900 accepts Sony’s E-mount camera lenses, of which there are 13; they don’t quite exploit the full area of that jumbo sensor. But the camera comes with an adapter for the older, more plentiful A-mount lenses. Alas, those lenses don’t autofocus with that adapter.The most astonishing new full-frame Sony, though, is the RX1. It’s the world’s first compact full-frame camera. Now, you’re forgiven if you just spewed your coffee. “Compact” and “full-frame” have never gone together before. Everyone knows why: A big sensor requires a big lens, meaning a big camera. You can’t change the laws of physics, no matter how much photographers would love it.

But somehow, incredibly, Sony’s engineers have done it. The RX1 is easily coat-pocketable, but yes, there’s a full-frame sensor in there, and the photos it delivers are breathtaking.You’ll pay a crazy price for this achievement: $2,800 (Rs 1,51,983). That’s not out of line for full-frame cameras, but it’s more than the full-frame Nikon D600 ($2,000 or Rs 1,08,559), for example.

That’s not the only price you’ll pay for this amazing act of miniaturisation. This camera doesn’t zoom, apart from a 2x digital, fake zoom. And its lens is permanently attached. To make the whole thing smaller, Sony cleverly hid part of the long lens inside the camera’s inch-thick body; still, you can’t swap out lenses. Something had to give.

So who on earth would pay $2,800 (Rs 1,51,983) for a non zooming camera? Believe it or not, they’re out there. The Sony RX1 takes certain photos better than any other pocketable camera in the world.

Low-light shots, for example. The camera has a small built-in flash, but you’ll rarely use it; incredibly, this camera picks up more light than your eyes do, thanks to both its huge sensor and its f/2.0 Zeiss lens.

The RX1 captures perfectly balanced, nicely illuminated shots in dimly lighted restaurants, candlelight, street corners at night, making them all look much brighter than they actually are. Full-frame cameras like a Canon 5D can do that, too – but to bring one of those along, you’d need a carrying case, not a pocket.

The RX1 also takes lovely portraits. One reason is that this camera creates beautiful blurry backgrounds. That soft-focus background effect is a hallmark of professional photography – and of big-aperture, big-sensor cameras. Until now, few pocket cameras could defocus the background at all. The RX1 does very well with close-ups, too. You can get about 5.5 inches away from your subject – close for a full-frame camera, even with a macro lens.

Video is gorgeous, too: 1080p high definition with stereo sound. There’s a miniplug input for an external microphone, too. 

Unfortunately, there are also some aspects that will drive you crazy. Focusing can be slow – in low light, really slow; as a result, this isn’t a great camera for sports, pets or children. There’s no stabilisation for still photos, either. And you can’t play back stills and videos consecutively. You have to dive into the menus to switch from one form of playback to the other. That’s common to other recent Sony cameras, and it’s idiotic.

If Sony follows its usual pattern, it will follow up the RX1 with other models that address some of these shortcomings.