The RX100 not only boasts the highest-resolution sensor here, but also the largest. Its 20.2MP resolution should in theory allow for more detail and better enlargements, although being the second lightest on test may give it a disadvantage with regards to steady handholding. Still, to ensure images are as sharp as possible, Sony has equipped the 28-100mm optic with Super SteadyShot technology, and while the impressively wide f/1.8 aperture at the wide end should also help in this regard, its tailing off to f/4.9 at the 100mm end is a pity.
Images are recorded to both Raw and JPEG formats, while control over exposure is also possible through full HD video recording. The 3in WhiteMagic LCD screen boasts the highest resolution out of the septuplet of cameras here, with the 1.2million dots comprising an extra white dot for each RGB trio.
Slightly thicker than the XF1 but overall still the most compact camera here, the RX100 has decidedly few external controls, and those that are present are definitely on the small side. The rear is dominated by the 3in LCD screen, although in addition to the key controls present, it's nice to see enough space has been left for a small menu pad dial and thumb rest.
It's impressive to think that the smallest camera here not only sports the largest sensor but still manages to squeeze in a respectable 28mm start on its lens. Less impressively, although the aluminium body gives the impression of strength, as soon as the power button is pressed the slight give around this area is noticeable. The lens's control ring moves fluidly, though, but its shallow profile may make it awkward for users with larger-than-average hands.
As the resolution charts show, not only is the RX100 capable of resolving more detail than the other cameras here, but it manages to maintain this excellently at high ISOs. Correct focus and appropriate shutter speeds, however, become more critical, as the higher resolution means that smaller inaccuracies are more easily spotted when images are viewed at 100%. While some corner softness is visible at wider apertures, the lack of distortion from the lens is surprising.
The metering system is also one of the most reliable on test, although AWB performance under artificial light could be improved. Colours are generally neutral rather than vibrant.
The RX100 has a marginally slower start-up time next to the other compacts here, despite it not being terribly slow in itself. It can take a while for the camera to power down when writing images, though, which makes putting it away quickly a touch more inconvenient, but its shot-to-shot times are excellent.
The focusing system is also impressively prompt and reasonably discreet, although in quieter conditions the whirring of the lens as it zooms through its focal range can hamper discreet shooting. The screen is of a high standard though, with excellent detail and fine contrast, while face detection works well to identify subjects.