The Mark IV performs every bit as impressively as previous RX100 cameras. JPEGs direct from the camera are bright and vibrant, with true-to-life colours that have just the right amount of saturation for most subjects. You can choose from a range of Creative Styles if you want to experiment with different looks, such as Vivid, Landscape and Portrait, but the Standard setting produces perfectly good results in most situations.
Plenty of fine detail is visible in images shot at the lower sensitivity settings of ISO 100-400. Detail gradually starts to be lost as you move up the sensitivity range when examining images at 100%, although images viewed at typical print and web sizes retain and impressive level of detail right up to ISO 6400; quality isn't quite as good at ISO 12800, but it's still possible to make a decent-looking A3 print.
Comparing the equivalent raw image files, with no noise reduction applied, with the JPEGs you can see chroma noise, or coloured speckling, in images captured at higher sensitivities from around ISO 6400, although no banding is visible. You can apply custom noise reduction to reduce the speckling while retaining a little more detail than is apparent in the JPEGs, so long as you don't mind retaining a little noise too.
Sample image: Direct from the camera, colours are nicely saturated without being overly vibrant; you can experiment with different Creative Styles if you want more (or less) saturation. Click here to see a larger image.
Sample image: The wide f/1.8 maximum aperture enables you to restrict depth of field very effectively – and it only rises to a still-impressive f/2.8 at the telephoto end. Click here to see a larger image.
There's a small but marked improvement in signal to noise ratio performance, as indicated by our lab tests, when comparing the RX100 IV with the Mark III, especially when looking at raw images. The same can be said for dynamic range, more so at the lower end of the sensitivity scale, between ISO 100 and ISO 800.
Sony's general-purpose multi-segment metering system works well most of the time in a range of shooting conditions, only requiring you to apply exposure compensation in the usual situations, such as when shooting very bright subjects or high-contrast scenes.
During my tests I tended to leave the Dynamic Range Optimiser on the Automatic setting. This feature helps to produce balanced exposures by analysing a scene and processing different areas of the image to retain more information in highlights and shadows; if you're shooting a scene with areas of very high contrast it can be useful to push the DRO up to level 5, but you may find it can cause an image to look a little unrealistic, so it's something of a trade-off.
Sample image: The RX100 IV's low-light performance is impressive – its AF system was able to focus on this fine wire in very dark conditions, but I could barely see the wire while shooting. Click here to see a larger image.
Sample image: There are a few different Picture Effects on offer, such as this Miniature Effect. You can't shoot raw when using these though, meaning you're stuck with the effect whether you like it or not. Click here to see a larger image.
I found that the RX100's auto white balance setting coped well with a range of different shooting conditions, including under artificial light, but you can choose from the usual range of presets if you find that auto isn't giving you the results you want. The Shade setting can produce images that are a little warm, which may be to your liking, while other settings, such as Sunlight, tend to produce more accurate colours.
Autofocus speeds are pretty snappy, with the RX100 IV able to accurately and swiftly lock onto subjects in good light. As light levels drop the camera tends to take a little longer to focus, but it still manages to acquire positive focus even in very dark conditions. Handily, you can change the size of the focus point to small if you're photographing subjects that aren't well defined.
Sample image: The RX100 IV's 24-70mm equivalent zoom range isn't huge, but it gives you plenty of scope to shoot most everyday subjects. Click here to see a larger image.
Sample image: Having a tilting screen gives you scope to shoot from some awkward angles, such as very low down. Click here to see a larger image.
For a compact camera the 2.9x optical zoom length of the RX100's lens may seem a rather paltry offering, but its 35mm equivalent of 24-70mm is the focal range that many DSLR users typically work with. As a bonus you get a wide maximum aperture at both ends of the optic – f/1.8 at the widest setting and f/2.8 at the telephoto end, both of which enable you to effectively blur the background to great effect, and use fast shutter speeds.
Sony is pushing the video capability of its new RX cameras, and not surprisingly given the addition of 4K video. The RX100 IV is limited to five minutes of 4K video recording at a time, but that shouldn't present too much of a problem if you're shooting lots of short clips to edit together. Although quality is good at both 4K and full HD, it's possible to see a slight jello effect when panning the camera – it's especially noticeable in 4K video shooting, so full HD is recommended if you're a fan of panning shots.