Sony RX100 IV review - a powerhouse compact

The Sony RX100 IV is a camera for people who shudder at the thought of compromise. The combination of a 1in sensor and an f/1.8-2.8 lens gives it the same light-gathering ability as a full-frame camera with a f/4.9-7.6 lens. This is marginally better than virtually every SLR and CSC with their kit lenses, so we can expect image quality to be in the same league. It’s far smaller than any SLR or CSC, though, weighing 298g and measuring just 41mm thick. It slips easily into all but the tightest of trouser pockets, and can be carried around all day.

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Whereas its closest competitors, the Canon G7 X and Canon G5 X make you choose between an electronic viewfinder (on the G5 X) and a truly pock-sized design (the G7 X), the RX100 IV incorporates a high quality viewfinder that retracts into the camera when it’s not needed. There’s also room for an articulated LCD screen, which tilts down by 45 degrees and up and over by 180 degrees for self portraits. Continuous shooting is phenomenally fast at 16fps, or 5.5fps with continuous autofocus. Video enthusiasts will love the 4K video capture, the built in neutral-density filter for wide apertures in bright light, plus the ability to shoot 1080p video at up to 1,000fps for 40x slow motion.

In fact, the RX100 IV has so many talents that it’s easier to list the things it can’t do. The screen isn’t touch-sensitive, and there aren’t many single-function buttons for quick access to settings. Exposure compensation, drive mode and flash settings have dedicated buttons, and the latter two plus a Custom button can be assigned to various other settings. A rear wheel and lens ring provide quick access to manual exposure settings, but photographers who like to take control will spend a fair amount of time navigating the menus. There’s no hotshoe for external flashguns and wireless triggers, although I can’t imagine many people will miss this. Battery life is on the short side at 280 shots, but better than the rival Canons’ 220 shots.

The 2.9x zoom with its 24-70mm equivalent focal length range is relatively modest. It’s smaller than the Canon G7 X and G5 X’s 25-100mm range but not much different to an SLR or CSC’s kit lens, which typically has a 27-82mm equivalent focal length range. That brings me to another limitation. The RX100 IV can’t swap its lens for another. That might be stating the obvious, but it’s something I’d think about carefully before investing £759 in a camera. This sensor and lens combination compares well with an SLR or CSC with a typical budget kit lens, but it can’t compete with wide aperture, telephoto and other specialist lenses. This is the main compromise that comes with the tiny design. You could buy a budget CSC and a couple of additional lenses for £750, but they’re not going to slip into your back pocket.

I expect a £750 compact camera to be an absolute delight to use, but the RX100 IV doesn’t quite hit the spot for me. The smooth metal front leaves little to hold onto. Even a small ridge would have made it more secure in the hand. Its buttons are on the small side, and basic adjustments to settings can be cumbersome. The Canon G7 X and G5 X are much better in this respect with their touchscreen-controlled autofocus and dedicated exposure compensation dials.

The RX100 IV is much faster than the two Canon cameras, capturing a photo every 0.4 seconds in normal use. Autofocus speed was particularly impressive, taking around 0.3 seconds even in very low light. I noticed more autofocus errors than normal, though, averaging about 5 per cent across my tests. That’s still on the right side of acceptable in my book, and the speed at which the RX100 IV can fire off shots makes it easy to take two or three for safety. Continuous mode came in at 15.5fps in my tests, and lasted for 47 JPEGs before slowing to 5.1fps - a phenomenal result. RAW capture was slower at 8.5fps, dropping to 1.6fps after 27 frames. That’s still faster than most cameras at this price manage for JPEGs.

Video quality and slow motion

This fast performance also brings big benefits for video capture. The 4K video mode produces 8-megapixel frames - four times the resolution of 1080p video - and picture quality is fantastic. Details were significantly sharper than any 1080p footage, not just when viewed on a 4K display but also when resized to 1080p resolution. The camera switches to a flatter colour profile for video than for photos, which gives a better starting point for colour grading in editing software. Autofocus was smooth and reasonably responsive, although without a touchscreen it’s not really feasible to move the autofocus point around while recording.

Slow-motion video gives a sense of grandeur to virtually any subject, and the RX100 IV’s slow motion mode (along with its sibling the RX10 II) http://www.expertreviews.co.uk/digital-cameras/bridge-cameras/1404105/sony-rx10-ii-review is the best implementation I’ve used. 1080p video is captured at a choice of 250fps, 500fps or 1,000fps for 10x, 20x or 40x slow motion. It’s not quite as good as it sounds, though. Videos are encoded at 1080p but the sensor readout drops as the frame rate goes up. The 20x and 40x modes aren’t really up to scratch but 10x slow motion looks superb.

Autofocus and exposure must be primed before recording can commence, and capture is limited to two seconds, whereupon the video is played back in slow motion as it’s written to the memory card. This makes the process pretty labour-intensive, but that’s not necessarily a bad thing. It’s still worryingly easy to fill your hard disk up with masses of slow motion videos.

Image quality

The RX100 IV’s image quality is extremely impressive, too. The 1in, 20-megapixel sensor captures enough detail for A3 prints. Details looked clean, sharp and natural in brightly lit conditions, except for the occasional autofocus error described above. When a fast shutter speed or diminishing light placed higher demands on the camera, the bright f/1.8-2.8 lens helped to keep noise at bay.

My only real criticism is that the very similar Canon G5 X and G7 X are even better in low light, thanks to their superior noise reduction processing and slightly bigger zoom range. These differences are minor, though, and I wouldn’t choose one over the other purely on this basis. All three cameras use 1in sensors and f/1.8-2.8 lenses, and there’s little to separate them for image quality.

^ This high-contrast scene is expertly judged, with highlights just short of clipping, and details are sharp from edge to edge. (1/500s, f/4, ISO 125, 60mm equivalent)

^ Not all of my test shots were so successful. On a few occasions the autofocus was way off course. (1/80s, f/4, ISO 125, 69mm equivalent)

^ Precise, natural skin tones and a shallow depth of field are rare accomplishments for such a slim camera. (1/100s, f/4, ISO 125, 30mm equivalent)

^ Setting the shutter speed to 1/1,000s to freeze motion raises the ISO speed to 800. Skin textures aren’t as smooth but there’s not much evidence of noise. (1/1,000s, f/2.8, ISO 800, 49mm equivalent)

^ Shutter-priority mode at 1/1,000s once again, and this time the camera has resorted to ISO 1600. Skin and hair textures are looking a little coarse on close inspection, and focus isn’t quite pin-sharp. (1/1,000s, f/2.8, ISO 1600, 70mm equivalent)

^ The 1in sensor and f/1.8 aperture combine to deliver excellent image quality in low light. (1/30s, f/1.8, ISO 500, 24mm equivalent, -0.7 EV)

^ This much darker scene was captured at ISO 3200. There’s a fair amount of noise and not much detail when viewed up close but it’s hard to fault at normal viewing sizes. (1/50s, f/2.8, ISO 3200, 41mm equivalent)

^ ISO 6400 tells a similar story - this shot doesn’t stand up to scrutiny but it’s an excellent snapshot for such a small camera. (1/25s, f/2.8, ISO 6400, 70mm equivalent)

^ Skin textures are a tougher test at ISO 6400. Details are smeared and smooth gradients look grainy. (1/40s, f/2.8, ISO 6400, 51mm equivalent)

Conclusion

There’s no denying that the RX100 IV is a hugely impressive camera. At this price it really needs to be. It’s not perfect, but there’s nothing here that I’d classify as a deal-breaker. Its only real problem is some formidable competition. I prefer the Canon G7 X and Canon G5 X’s controls, with their dedicated exposure compensation dials and touchscreen-controlled autofocus. They also have the edge for image quality with their slightly bigger zooms and smoother noise reduction. Canon makes you choose between an optical viewfinder and a truly pocket-sized design, but I’d be happy to live without a viewfinder when the G7 X costs £380.

Then again, if you want the viewfinder, 4K video, 1080p slow motion and blistering performance, all squeezed into your pocket, the Sony RX100 IV is uniquely placed to deliver it.