On first contact, the Sony RX100 is reminiscent of some of the well-known expert compacts already on the market, like Canon's S series—in particular the S95. They're actually very similar cameras to handle, with bodies of comparable size and general design. The two models even have the same smooth and slightly slippery front face, a problem that was neatly overcome in the Canon S100 with the addition of a small grip bar. The RX100 has a similarly robust build too, with careful assembly and finish, and no unsettling wobbles to the controls ... even if the font face feels quite plastic.
Obviously, the cameras are a little different. The control ring around the lens is a bit easier to access in the RX100 and moves smoothly rather than in notches. While it's quieter and more discreet to use, this can also make it harder to adjust settings with the same level of precision. The lens takes up more room in the RX100 too, and we found our middle finger often rested against the barrel.
Another difference is the cameras' interfaces, as the RX100 menus are lifted straight out of Sony's Alpha SLRs, with a nicely updated Fn menu that's been made clearer and totally customisable.
The RX100 screen has VGA resolution and is an RGBW-type display, as seen in the likes of the Ricoh GR Digital IV. However, Sony hasn't calibrated its screen in the same way as Ricoh. While the Ricoh had a good gamma and colour temperature but wasn't great with colour fidelity, the Sony has boosted contrast (which overexposes light tones a little), a general cold overtone, and improved fidelity in highly saturated colours—although duller colours aren't rendered as well (the average Delta E is 5.4). Ultimately, the onscreen image could be more accurate, but the RX100 has a good compact camera screen that's pleasant to use in spite of its rather noticeable reflections.
Although the RX100 can easily be used by beginners thanks to its intelligent auto modes, this is clearly the kind of camera that advanced users can get much more out of. The customisable interface, the control ring around the lens and the handy settings wheel over the four-way controller keep key functions easily accessible for expert snappers. There's even a RAW mode for versatile post-editing (a first in a Cyber-shot camera since the R1!).
When deployed, the RX100's 3.6x zoom lens is as big as the lenses seen in many superzoom compacts (due to the size of the sensor), so it's no surprise to see a slightly sluggish start-up time of just under two and a half seconds.
The autofocus is nice and consistent, working in around half a second in all conditions. While some cameras prove quicker in good light (although the difference isn't really that noticeable), Sony's system is definitely above average in low-light conditions. That's no doubt thanks to the lens aperture as well as the sensor's various qualities.
Photo-to-photo turnaround is nice and fast, as the RX100 can take a picture every second. It's nice to see that this speed is maintained in RAW mode too, so advanced photographers can shoot away with no extra restrictions.
The burst mode tops 7 fps for Jpeg shots or 4.7 fps for RAW (for eight photos). That's clearly no match for Sony's SLRs, but it's excellent for a compact camera.
It's in this field that we're really keen to see what the RX100 is made of. The camera's sensor is two to four times bigger than those used in regular compact cameras, and has almost double the resolution (20 Megapixels). On top of that, Sony has even managed to pack a 3.6x zoom lens into a camera body just 37 mm thick.
The sensor's pixel density (17 Mpx/cm²) is only a bit lower than regular expert compacts (27 Mpx/cm² for the Canon S100, 23 Mpx/cm² for the Canon G12, 21 Mpx/cm² for the Fuji X10) but much higher than interchangeable lens compacts (8.6 Mpx/cm² for the Nikon J1, 7 Mpx/cm² for the Panasonic GX1). We can therefore expect sensitivity to be handled in a similar way to the other compacts—in full sized shots, at least (on two identically sized prints, a higher definition will visibly refine and mask noise).
And the results are a nice surprise. The ISO test shots from the RX100 are quite clearly superior to those shot with regular expert compacts. Although the relatively heavy image processing won't necessarily be to everyone's taste (but there is a RAW mode for users wanting to get around that), full-sized images come out virtually impeccable up to 1600 ISO. At 3200 ISO, smoothing is more visible and noise can be spotted in dark, shadowy parts of pictures, but general quality is still excellent and an 8" x 12" (20 x 30 cm) photo will look perfect. It's only at 6400 ISO that precision and sharpness really drop, with levels of detail that could prove borderline for 8" x 12" prints.
So what about that lens? Is it really possible to pack a 3.6x lens for a 1" sensor into a package less than 4 cm thick while still maintaining a resolution sufficient to get the best out of those 20 Megapixels?
At wide-angle settings, the answer to that is clearly yes. Resolution isn't up there with the Alpha 77 with a 16-50 mm lens, but quality stays at a very good level from the centre of the frame right to the edges, with just a slight loss in sharpness visible in the corners of shots at 100% size. With quality like this, the RX100 lens stands head and shoulders above the rest of the compact market. Plus, textures are rendered in a very impressive way, as you can see in the picture of the book cover above.
Things are a little less impressive in telephoto mode. The centre of the frame is excellent, but inconsistencies in quality over the frame are more noticeable on full-sized images. The Canon G1 X does a better job (although it's much bulkier!) and even Canon's S100 isn't left wanting, in spite of its lower resolution. That said, an 8" x 12" (20 x 30 cm) print or even a 12" x 18" (30 x 45 cm) picture will look perfectly fine.
The RX100 films Full HD video at 50 frames per second with stereo sound. Image quality is good, with bright, light areas rendered well and generally pleasant results. The optical zoom is active but has been slowed down for video mode, and the continuous autofocus works quite well.
Audio quality is very good too. The stereo effect is nice, plus distinct noises are rendered accurately and voices sound relatively clear and recognisable.
Note that you can take a photo while filming video with the RX100—it's a 16:9-format shot but is taken in full resolution (which works out at 17 Megapixels).