Sony RX10 Review -- Tech Info

by Mike Tomkins and Dave Etchells

Sensor. It might have a completely different form factor, but the Sony RX10 is based around the exact same 20.2-megapixel, 1.0"-type Exmor R CMOS image sensor seen previously in the Sony RX100 II.

Typical point-and shoots with similar zoom reach use a 1/2.3"-type sensor; the RX10's sensor is almost 4.1x larger. All other things being equal, that greater size translates to more light-gathering area, and a better signal-to-noise ratio. (Read: lower noise.) On the other side of the coin, though, the RX10's sensor area is only about one-third the size of an APS-C sensor, as used by most DSLRs and some CSCs.

Backside illumination. We mentioned that the Sony RX10 uses an Exmor R-branded image sensor, indicating that it's a backside-illuminated design. BSI sensors move their circuitry beneath the active layer of the sensor, as shown in the diagram below, so that incoming light isn't blocked. That gives the RX10's chip an advantage in terms of sensitivity and noise performance, compared to a standard image sensor of the same size.

Sensitivity. The RX10's image sensor offers sensitivity ranging from ISO 80 to 12,800 equivalents. Although it uses the same image sensor as the RX100 II, and has the same upper sensitivity limit, the lower end of that range reaches a little further. (The RX100 II bottoms out at ISO 100 equivalent.)

As in Sony's other recent cameras, there's a multi-shot function which reduces image noise by averaging subsequent exposures. Dubbed Multi-Frame NR, this function has an upper limit of ISO 25,600 equivalent.

Performance. Thanks in part to Sony's new BIONZ X image processor, the RX10 is capable of shooting at a fast burst rate of 10 frames per second in Speed Priority Advance mode, which locks focus (but not exposure) from the first frame.

Ordinarily, the performance is more modest, ranging from 2.5 fps for raw+large/fine JPEG to 3.1 fps for JPEG images, in continuous burst mode with autofocus between frames. Burst depth in this mode is 13 raw+large/fine JPEG or 30 JPEG frames.

Lens. The Sony RX10's 8.3x optical zoom lens is its headline-grabbing feature. For one thing, it offers far more reach than the lenses of other RX-series cameras, covering everything from a 24mm-equivalent wide angle to a 200mm-equivalent telephoto. That's a pretty good walkaround range, with enough reach to pull the action up close, and enough wide angle for architecture, interiors, group photos, and the like.

Even more impressively, though, the Carl Zeiss Vario-Sonnar T*-branded optic has a constant aperture, unlike most long-zoom lenses. It doesn't matter where you are in the zoom range, a maximum aperture of f/2.8 is available. Focusing is possible to as close as 1.2 inches (3cm), for some impressive macro shots, as well.

The lens' optical formula is not surprisingly quite complex, including 14 elements in 11 groups, of which seven elements are aspherics. There's also a seven-bladed, rounded aperture, and a T* coating which reduces ghosting and flare. There's also a built-in 3-stop neutral density filter, which can be deployed automatically or manually as needed to attain a slower shutter speed, or disabled if you prefer not to use it for a given shot.

Stabilization. As you'd expect, Sony has included its Optical SteadyShot lens-based image stabilization in the RX10. For video capture, the system provides a greater corrective range; Active Mode, in Sony parlance.

Focusing. When they briefed us on the RX10, Sony called particular attention to the new autofocus drive system it contains. It's a contrast-detect AF system, but the company has made major strides in AF speed, thanks to the combination of a CMOS sensor with very fast readout, a greatly-enhanced image processor, and an all new hybrid-drive AF actuator.

To understand what this is all about, it would help to take a moment to understand how contrast-detect AF works in the first place.

The basic idea behind contrast-detect AF is that crisp detail means the maximum brightness difference between adjacent pixels, wherever there's a contrast edge in the original subject. Think about it - when an image is out of focus, everything is soft and blurry, and nothing changes very rapidly as you move across the image. On the other hand, when an image is crisply focused with fine detail, the brightness will change much more abruptly as you look across the image. This is the basis of contrast detection. The camera looks across a row of pixels, and adds up the differences from one pixel to the next, all across the image (or all across the area it's concerned about evaluating focus for). The summed differences between pixels is a measure of the overall contrast of the image, which in turn is a measure of how well the image is focused.

This is a relative measurement, though, since the summed contrast will vary enormously depending on the subject. The only way the camera can tell whether the focus is optimum, then, is to measure the contrast, adjust the focus slightly, and measure the contrast again. If the contrast number increased, the focus improved. If it decreased, it worsened.

Most people understand that being able to make the contrast measurement quickly will be key to being able to focus rapidly, but fewer realize how critical it is to be able to move and stop the lens quickly. After each contrast measurement, the camera must move the lens a precise amount, and then have it stop moving before the next measurement can be made. It turns out that this last requirement is one of the most difficult to achieve. It's (relatively) easy to make a lens motor more powerful, so it can get the lens moving quickly, but it's often another matter to bring it back to a stop with equal quickness.

Sony developed a special hybrid actuator for the RX10, making dramatically faster AF cycles possible. The RX10 uses a standard ultrasonic-wave motor to get the lens moving, but then uses a special piezoelectric actuator (borrowed from Sony's sensor-shift image stabilization technology) to stop the motion quickly and precisely. As it was explained to us, the piezo actuator in this case isn't so much operating as a driver, but rather as a brake. Apparently, the ultrasonic-wave motor is good at getting things moving, but not so good at stopping them, hence the need for a brake or "friction clamp", in the form of the piezo element.

The NDA briefing was a little sparse on deep technical details for this, but if we understood correctly, Sony says that this hybrid system can complete 50,000 start-move-stop cycles per second(!) That's apparently how many cycles the focus-actuator system can perform per second, but it's not clear how many cycles the camera actually performs in practice, as clocking the image data off the array and performing the contrast measurement will add at least some time to the process, and we don't know whether the 50K/sec spec included the contrast measurement process or not. It's likely that contrast measurement is very fast, though, given how fast we know the array can be read (from the video processing mentioned elsewhere), and that we know the new BIONZ X processor has an enormous amount of processing horsepower to bring to bear.

Regardless of the cycle rate, though, this new system clearly works. Our lab testing found autofocus on the Sony RX10 to be as fast as most consumer DSLRs using phase detection. And this was also borne out in our real-world shooting with the camera, too: It focused quickly and confidently, and nailed focus right where we wanted it most of the time.

Viewfinder. The Sony RX10's body has SLR-like styling, and that provides plenty of room for a viewfinder. Of course, there's no reflex mirror here, and so it's not an optical viewfinder. Arguably, though, it's better. It's an electronic viewfinder, and one that's clear, bright, sharp even in the corners, and with very generous magnification.

The RX10's EVF is based around a 0.39-inch organic LED display, and has 100% coverage. Resolution is 800 x 600 pixels (that's 1,440,000 RGB dots), and magnification is 0.7x with a 50mm lens at infinity.

Tilting display. We found ourselves using the electronic viewfinder most of the time, but that's no reason to skimp on the LCD. Fear not, Sony didn't do so. It's retained the same VGA (640 x 480 pixel; 1,228,800 RGBW dot), WhiteMagic-branded unit used in the RX100 and RX100 II. That's great news, because it pairs good resolution with excellent outdoor visibility -- even under sunlight. (And indoors, the design saves power, since the backlight can be run dimmer than a standard RGB LCD at equivalent brightness.)

The RX10's LCD is articulated in just the same way as that of the RX100 II, and allows tilting upwards by 84 degrees, or downward by 45 degrees. It's great for shooting from the hip, low to the ground, or over your head, and makes the RX10 significantly more versatile than cameras with a fixed screen. It's not quite as versatile as side-mounted tilt/swivel displays, though, offering no help with self-portraits or shooting high / low shots in portrait orientation.

Dials and rings and levers (oh my!) The Sony RX10 sports a triple-dial design, if you count the combined multi-function controller / dial on the rear of the camera. It's not the traditional front-and-rear dial arrangement you'd find on most SLR bodies these days, though. Instead, the front dial is replaced by an aperture ring around the lens barrel as it did in the days of mechanical aperture linkages. Don't be fooled, though: It's still a fly-by-wire design, even if it's a very nice one. (A particularly rare touch is the ability to switch between a stepped and a smooth, click-free rotation on the dial, courtesy of a switch on the bottom of the lens.)

Two of the three actual dials are on the rear of the camera, and neither is the most satisfying. The upper dial is presented end-on, is very small, barely protrudes from the camera, and is consequently not terribly easy to locate and turn by feel with your thumb. The lower dial sits face-on, and is easily located and turned -- but perhaps a little too easily so. It defaults to control of ISO sensitivity in most modes, and accidental bumps can cause unintended sensitivity changes. Thankfully, the dial's function can be changed or disabled altogether, if you find it to be an issue.

The remaining dial is dedicated to exposure compensation, and sits on the top deck. Its presence makes clear this is a camera aimed at enthusiasts, who want the quickest access possible to important exposure features like these, and don't want to be caught hunting in the menu system while there's a photo opportunity slipping away.

There's also a dedicated zoom ring around the lens barrel, as well as a zoom rocker around the shutter button. The zoom ring, like that for aperture control, is fly-by-wire rather than a mechanical linkage. Ordinarily, you can use either control for zoom adjustment, but the ring around the lens is both more accurate and faster. If you enable manual focus, however, the ring around the lens becomes a focus control, leaving zoom control to the rocker.

Flash. The Sony RX10 includes both a built-in, popup flash strobe, and a hot shoe for external strobes. The popup flash is released mechanically with a small flash button just to its right, and it's very strongly sprint-loaded indeed, popping up quickly and with a loud "thunk".

Given the size of the camera and especially its lens, it doesn't raise terribly high, though. Even at wide-angle, and with the lens retracted to its shortest length, the flash is still partially blocked by the lens for any subject closer than a couple of feet. Sony rates working range as 3.3 to 33.5 feet (1.0 to 10.2m) using Auto ISO, and the maximum range at ISO 12,800 at 66.9 feet (20.4m).

For better flash exposures -- and bounce flash, which isn't possible at all with the internal strobe -- you'll want to switch to an external flash. Here, Sony offers up its Multi Interface Shoe, a proprietary intelligent flash hot shoe that's based on the standard ISO 518 hot shoe. This accepts strobes including the HVL-F20M, HVL-F60M, and the HVL-F43M (which includes an LED video light.) You can also mount older strobes including the HVL-F20AM and HVL-F43AM using an ADP-MAA Multi-Interface Shoe Adapter.

Sony doesn't state flash sync speed of the DSC-RX10.

Accessory Terminal. As noted, the RX10's flash hot shoe also doubles as an accessory terminal that accepts a variety of accessories. (Hence, the name Multi Interface Shoe). Not all of these will make sense -- for example, the Viewfinder and Wi-Fi accessories would duplicate features built into the RX10 -- but there are nevertheless quite a few options available beyond flash strobes. We've already mentioned the ADP-MAA shoe adapter. Other accessories you can attach include the HVL-LEIR1 video light, ECM-XYST1M stereo microphone, and CLM-V55 clip-on LCD monitor.

The Sony RX10 shoots sweep panoramas, but the stitching can be a bit iffy, as in this shot. (Notice the regular, repeated vertical bands in the trees, where individual trees are repeated more than once.)

Exposure. The Sony DSC-RX10 includes the usual array of operating modes -- Program, Aperture-priority, Shutter-priority, and Manual -- that you'd find on a consumer-oriented SLR or mirrorless camera. It also offers an Auto mode -- in lieu of the separate single-shot Intelligent Auto and multi-shot Superior Auto modes typically found on consumer-oriented Cyber-shot models -- plus a Movie mode, a Sweep Panorama mode, and two Memory Recall modes that let you save settings groups for quick access. And, of course, there's a generous selection of user-friendly Scene modes.

Metering modes include Multi-Segment, Center-weighted, and Spot. Shutter speeds range from 1/3,200 to 30 seconds, plus Bulb, although the longest time varies depending on exposure mode.

Creative. Like the RX100 and RX100 II, the Sony RX10 features a wide variety of Sony-specific tools aimed at making it easier to get great photos. (Or at least, what the camera feels to be great photos, greatness being a rather subjective thing.)

The Clear Image Zoom function is based on what Sony calls By Pixel Super Resolution algorithms. In essence, it's a digital zoom that tries to improve quality by using pattern matching. (A standard digital zoom function is also available, but the two can't be combined). Clear Image Zoom interpolates (read: guesses) missing data, but does so in a more intelligent manner than the standard digital zoom.

The underlying pattern-matching, interpolating algorithms also come into play for Auto Portrait / Object Framing, which uses face / subject detection to locate your subject, and then recrops the image based on a rule-of-thirds algorithm for a more pleasing layout. After cropping, your image is interpolated back up to the same resolution as the original shot. Both your original and the new shot are saved separately, so if you don't like the results, nothing is lost.

There's also still a Self Portrait Self-timer function, which automatically starts a countdown timer when either one or two faces are detected in the scene, saving you the trouble of pressing the shutter button at all. Since the tilting display still can't face forwards, though, you're flying blind with this function.

The RX10 retains Sony's Picture Effects function for soft focus, watercolor, miniature, and many more effects, as well as the other creative functions we've come to expect: High Dynamic Range, Dynamic Range Optimizer, and 2D Sweep Panorama.

Level gauge. The RX10 features a dual-axis level display function, which helps you avoid tilted horizons and converging verticals. Since it also has an electronic viewfinder, the function is particularly helpful, letting you see and account for pitch and roll even when framing against your eye.

Movies. Sony is making a pretty big deal about video performance with the RX10, and with some justification. The Sony RX10 ticks off all the proper check-marks for video shooting, including jacks for both external microphones and headphones. It also has real-time audio level readouts and 31 steps of manual level control. When it comes to video specs, it's capable of recording Full HD (1080p60) high-definition video in the AVCHD format, at a 28 Mbit/second data rate. (Very good, if not full pro quality.)

There's also a 3-stop ND filter built in, that can be activated manually or automatically. The significance of this is that you can shoot video with the RX10 in bright daylight with reasonably large apertures, while maintaining low enough shutter speeds that your video won't look choppy. (And yes, the RX10 has full Program, Aperture-priority, Shutter-priority, and Manual exposure control in video mode.)

Speaking of full exposure control, one very nice touch for the Sony RX10 is that the aperture ring has a mechanical switch on it, to disable the 1/3-stop click detents. This is great for video shooting, as you can shoot in aperture-priority or manual-exposure modes with silent aperture actuation. Very slick, even if the aperture itself does still move in steps (and so does cause noticeable shifts in brightness)!

Sony RX10 - De-clickable Aperture Ring Demonstration

Where the Sony RX10 really breaks new ground for video, though, is that it's the first camera we're aware of that reads out the entire sensor pixel array for every frame, performing sub-sampling/video anti-aliasing in the processor. This addresses the huge bugaboo of still-camera video recording, namely the tendency towards moiré and false-color artifacts, thanks to the mismatch between still-image and video resolution.

Pretty much every digital still camera we've tested produces very noticeable moiré patterns and color artifacts in its video. (The Canon 5D Mark III deserves note as doing better than most, but even it still shows some level of video artifacts.)

The issue is that still cameras have to get rid of a lot of their image data in order to output a 1,920 x 1,080 video image. They usually don't have enough processor horsepower to do a proper job of sub-sampling the image in the vertical direction (across scan lines), so resort to simply skipping rows of pixels, jumping 2, 3, or 4 rows for each one actually output. The problem with this is that the image data is way undersampled from an image-processing standpoint, so moiré and artifacts are pretty much guaranteed. It's not that the industry doesn't know what to do to prevent the problem, it's just that there isn't enough processing horsepower available to do what the job requires -- until now.

Besides its advantages for still image processing, the new BIONZ X processor in the Sony RX10 has a special LSI front-end processing section ideally suited to processing huge amounts of video data on the fly. For the first time (that we're aware of), the RX10's processor clocks the entire 20-megapixel image off the array up to 60 times/second, and then sub-samples the raw image data digitally (think of it as a special class of signal averaging), to produce the final 1,920 x 1,080 video image. Doing so effectively performs a low-pass filtering operation on the video data, thus greatly reducing the propensity for moiré and false color artifacts.

While we didn't find the RX10 to completely eliminate moiré patterns, they were greatly reduced relative to just about every other camera we've seen, and there were no false-color artifacts to be seen anywhere. Not only that, but the video itself was very clean and crisp-looking, so the reduction in false color and moiré didn't seem to come at the expense of mushy subject detail.

The RX10 is also rare -- perhaps unique, among point-and-shoot cameras -- in providing uncompressed HDMI output without any overlays, if you want to record straight to an external device without your video getting trampled on by a compression algorithm. It can also display 4K stills via HDMI, incidentally, an even rarer feature.

With its constant-aperture f/2.8 24-200mm equivalent lens, advanced video capabilities, and compact size given the focal length/aperture range we suspect the RX10 will open up new video applications that have been impossible until now.

Wireless networking. Much like the compact Sony RX100 II, the RX10 includes built-in Wi-Fi and Near Field Communications radios. This is big news if you're a fan of social networking, because it means you can get your photos and videos off the camera via your smart device, without the need for third-party hardware.

And if you have an NFC-compatible device, you can even establish a connection without any intervention at all -- just enable NFC on the smart device if necessary, and then hold the two devices together briefly. This is enough for a Wi-Fi connection to be negotiated between both devices, and your data then transfers via that high-speed connection.

Unfortunately for iPhone and iPad users, Apple has yet to implement NFC in any of its devices, but many newer and more sophisticated Android and Windows Phone devices support NFC.

Once paired, you can not only transfer data between camera and smart device, but also remotely control the camera's shutter, and view a live view feed. That could prove very handy, whether you're looking to film skittish wildlife without getting too close yourself, or just want to confirm everybody's standing in the right place before tripping the shutter on a group portrait.

Wired connectivity. Four ports sit under flaps on the left side of the camera: a 3.5mm stereo microphone input, a 3.5mm headphone output, what Sony dubs the Multi Terminal, and a micro HDMI port for high-definition video output. The HDMI port can provide both uncompressed video with no overlays at Full HD resolution, and 4K still images, if you have a 4K display. The Multi Terminal is both a USB port, and a wired remote control port compatible with the RM-VPR1 remote commander, and tripods such as the GP-VPT1, VCT-VPR1, VCT-VPR10, and VCT-VPR100 which feature built-in wired remotes.

There's also the aforementioned Multi Interface Shoe on the top deck, which allows a variety of accessories to be connected to the camera.

Storage. The Sony RX10 stores data on SD cards, including the higher-capacity SDHC and SDXC cards, and the higher-speed UHS-I cards. It also accepts Sony's own Pro Duo / Pro HG Duo types.

Power. Sony is using an NP-FW50 InfoLithium rechargeable battery pack in the RX10. The company rates the combination as good for 420 shots on a charge to CIPA testing standards, which includes 50% flash usage and generous zoom usage.

Power consumption with the electronic viewfinder is significantly higher, at 2.7W versus the 2.1W of the LCD in record mode. That leads to a 20% shorter battery life of 340 shots with the EVF. If you plan to shoot predominantly with the EVF, you'll want to pick up a second battery.

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