DxO One review

We’re constantly being told that the camera market is in decline, with sales falling dramatically, particularly in the inexpensive zoom compact sector. Despite this, more pictures are now being taken than ever before, and shown to a larger audience through social-media channels such as Instagram and Facebook. This is all down to smartphones, of course, because since the advent of the iPhone 3G in 2008, smartphones have become the picture-taking tool of choice for many people. Indeed, with the excellent image quality possible from recent generations of smartphones, it’s now only enthusiast photographers who see the need to own a separate camera.

Yet smartphone cameras have their limitations. Sure, they’re slimmer, easier to use and deliver better image quality than most point-and-shoot film cameras ever did, but with their small sensors and tiny non-zooming lenses they have poor low-light image quality and allow little scope for compositional flexibility. DxO is aiming to address this with the DxO One – a camera that plugs into an iPhone via its Lightning connector, and uses a 1in-type sensor and fast 32mm equivalent f/1.8 lens to deliver much better image quality.

Various attempts have been made to address the shortcomings of smartphone cameras, most notably by Sony with its ‘lens-style cameras’, which have in turn been imitated by several other companies. These, in effect, are camera modules consisting of a lens, sensor, processor, battery and memory card, which are designed to use a smartphone as both screen and control unit, connecting via Wi-Fi. This may seem like a good idea at first, but it turns out to be less practical in reality. The Wi-Fi connection complicates image sharing from the phone, and drains the batteries of both devices, while the cylindrical shape isn’t particularly convenient to carry around, which rather negates the whole point.

DxO’s solution is to use a direct physical connection between the camera module and the phone, and make a much smaller device that’s genuinely pocketable. This immediately makes for a much more practical system than the Wi-Fi-connected devices we’ve seen until now. But is this enough to make the DxO One a must-have accessory for iPhone users?

DxO One Review – Features

The DxO One is based around the familiar 1in-type, 20.2-million-pixel sensor that’s used in an increasing range of enthusiast compact cameras, as well as the Sony Cyber-shot DSC-QX100 lens-style camera and the Panasonic Lumix DMC-CM1 smartphone. In DxO’s hands it offers a sensitivity range of ISO 100-51,200, with most other cameras that use it maxing out at ISO 12,800. In front of the sensor is a six-element, 11.9mm lens offering a 32mm equivalent angle of view, with an aperture range from f/1.8 to f/11.

On the back of the unit is a tiny monochrome screen that displays battery life, exposure settings, file format and the number of shots remaining on the card. Beneath it is a hinged cover for the MicroSD card slot and the Micro USB socket that’s used for charging the battery and transferring images to a computer. It’s worth noting that the DxO One has no tripod thread, so you’ll need to use some kind of clamp to attach it to a support.

Video recording is available, but with only a limited set of options. You can record in either full HD (1,920×1,080 pixels) at 30fps or HD (1,280×720 pixels) at 120fps, which is then played back at 30fps to give one-quarter-speed slow-motion footage. Exposure compensation can be applied before the start of recording, and electronic image stabilisation is available.

The device itself has only a single shooting control, which is a conventional two-stage shutter button on top towards the front. This means that the One can still be used in standalone mode when it is disconnected from an iPhone. At this point the camera works in fully auto mode, and employs face detection for autofocus when it can. It’s possible to switch between stills and movie recording by swiping a finger across the screen.

DxO One Review – Build and handling

With its robust shell, there’s little to fault about the DxO One in terms of build quality. It certainly doesn’t feel delicate, and I was quite happy dropping it into a bag or pocket when taking it out and about.

The lens is protected by a sliding cover when it’s not in use. Pulling this downwards turns the camera on and releases the sprung Lightning connector from its folded-in position. DxO says that the connector is quite unlike those used for other devices, such as charging docks, and has been tested to survive 38,000 connection/disconnection cycles. While it’s designed to connect firmly into the iPhone, it will also release when placed under stress, and is ‘fused’ so that it will fold into the body when pushed hard.

In practical use the One works rather well. This is due substantially to the rotating Lighting connector, as you end up with, in effect, a small camera module attached to a large rotating touchscreen for viewing and control. This isn’t unlike Nikon’s classic split-body Coolpix 900-series designs from the early days of digital, and the advantage is that you can hold the camera comfortably at waist level, rather than in front of you. It does, however, mean that you’re liable to shoot everything in landscape format.

I tried the One on the iPhone 5, iPhone 6 and iPhone 6 Plus. To me, it seemed better suited for use with the smaller-screened models, as the 6 Plus feels a little too large and awkward. In all cases, operation is very much a two-handed affair – one to hold the phone and the other to hold the camera. I wouldn’t trust the safety of either expensive device to the friction-based connection between them, no matter how well engineered it is. It’s worth pointing out that some phone cases can interfere with the connection too. The One can also be used on iPads with a Lightning connector.

DxO One Review – Autofocus

The DxO One uses a conventional contrast-detection system for autofocus, with the subject area selectable anywhere across the frame. Normally, the camera will try to select the subject automatically, prioritising faces when it detects them, but its choice can be overridden manually simply by tapping the screen.

In normal lighting conditions autofocus is fast and accurate, and it’s only when light levels drop extremely low that it struggles, such as in dimly lit interiors and streetlight-illuminated night scenes. Even then, if you can point the camera at a sufficiently high-contrast edge, it will usually find focus. Manual-focus override is available if necessary too, using an on-screen slider and magnified view in the centre of the frame.

DxO One Review – What is SuperRaw?

High ISO shots are inevitably noisy, simply because the sensor is capturing very little light. One way around this is to use multi-shot noise reduction, whereby the camera takes several shots of the same scene in quick succession and then combines them to make a composite image. The idea is that, because noise is random, it will average out and be reduced in the final image, while real detail should be retained.

Plenty of cameras can do this, but usually only when shooting in JPEG mode. What’s different about the DxO One is that it can shoot four frames in quick succession and record them together as a single SuperRaw file (in effect, four linked DNGs). Compatible software, including DxO Connect and DxO OpticsPro, can then convert the SuperRaw files to JPEGs.

SuperRaw files certainly give reduced noise at high ISOs, although the converted JPEGs can acquire a somewhat unnatural over-smoothed appearance. The bigger problem, though, is the sheer length of time needed to process the 80MB files. On my one-year-old Windows 10 Ultrabook, each took more than four minutes to develop, which isn’t really very practical. It’s possible to use a faster ‘HQ’ conversion that takes a quarter of the time, but this results in visibly higher luminance noise. Overall, given the resources it requires, I’m not convinced that SuperRaw is worth the effort.

DxO One Review – Operation

The camera’s shooting features are defined by the DxO One controller app. The first time you plug the device into your iPhone it will take you to the App Store and prompt you to download the app. Thereafter, it will automatically launch the app and go to the shooting screen, so long as the iPhone is unlocked.

The app itself is attractively designed and laid out. Its minimalism reflects the fact that there are relatively few features available. A control panel on the left side of the phone’s screen gives access to exposure parameters – shutter speed, aperture, ISO and exposure compensation – but there’s no live histogram or overexposure warning display to help guide your choices. It’s also possible to change white balance, metering mode and focus mode, including manual focus, but these settings are hidden away off-screen at the end of a scrolling list, with no visual cue to suggest they exist.

On the right side of the screen is a column of four buttons. The top selects file format, from JPEG, DNG raw and DxO’s unique multi-shot SuperRaw setting. Below that is self-timer (two or ten seconds), an option to use the iPhone’s flash and exposure-mode selection. In addition to auto, program, shutter priority, aperture priority and manual modes, there are scene modes for sports, portraits, landscapes and night scenes. The on-screen touch buttons are well separated and responsive, and the icons clear, making the app very easy to use.

DxO is keen to stress that both the app and the camera firmware can be updated automatically, and has revealed several features that it will add in the near future. These include an electronic levels display, burst shooting at 8fps with a 20-frame raw buffer, detailed exposure information overlay on the live view display, and the option to display Exif data during playback. Depending on how you choose to look at it, DxO is adding features for free based on early feedback, or it has launched the app before it is ready for prime time and is working on bringing it up to speed.

One of the DxO One’s key advantages compared to other add-on cameras is that it requires no messing around with your network connections. With Sony QX models and their various clones, so long as your phone is controlling the camera unit over Wi-Fi, it has effectively lost its connection to the internet. In contrast, with the DxO One JPEGs can be copied to your iPhone’s camera roll as you shoot, and can even be uploaded to social media directly from the DxO app without having to turn off or disconnect the camera. Alternatively, you can edit your pictures in the Photos app before uploading. Overall, the DxO One fits much better with how you normally use an iPhone compared to other ‘connected cameras’ I’ve used.

There’s a second side to the DxO One, though – it also has aspirations to be a serious camera, recording DNG raw files that can be opened in almost any imaging software and processed how you please. DxO supplies a very basic downloader/raw-converter program called DxO Connect and early buyers of the One will also get free lifetime licences to DxO OpticsPro, which is a more sophisticated raw converter with a greater range of adjustments and controls.

DxO One review – Performance

The whole point of the DxO One is to provide better image quality than mobile-phone cameras, and with its 1in sensor and fixed-focal-length lens it does just that. DxO has considerable experience in image processing, and it shows when looking at the One’s images. Colour rendition is pleasant, even in dull weather, with accurate yet saturated tones aided by well-judged auto white balance.

The lens is excellent. It is a little soft in the extreme corners at large apertures if you examine the images closely, but it gives sharp results across the frame when it’s stopped down to f/5.6. There’s no visible distortion or chromatic aberrations, so images look clean even when viewed close-up.

At low ISO sensitivities images are sharp, clean and highly detailed, and noise only starts to have an impact at ISO 800. At higher sensitivities there’s an inevitable deterioration of fine detail, but I’d still be reasonably happy shooting at ISO 1,600 and 3,200. Beyond this things go awry, and while ISO 6,400 and 12,800 are usable when necessary, the two Hi settings (equivalent to ISO 25,600 and 51,200) are a step too far.

The DxO One’s Achilles’ heel, though, is battery life. DxO claims it can shoot up to 200 frames per charge, but in my experience this is wildly optimistic. I found the battery meter dropped alarmingly quickly during normal use, and I rarely got more than 60 or 70 shots per charge, even when I got into the habit of turning it off immediately after every shot. This might be OK for casual users who take just a few pictures every couple of hours, and are used to recharging their phones at the end of every day, but in my opinion it seriously dents the DxO One’s credentials as a camera for serious photographers, who would probably be better served by an enthusiast zoom compact such as the Canon PowerShot G7 X or one of the Sony RX100 series. It is possible to recharge the camera from a power bank as you go along, and even shoot at the same time, but this isn’t very practical.

DxO One review – Lab Results

We have tested lots of cameras that use the Sony 20.2-million-pixel, 1in sensor over recent years, and the DxO One gives image quality that matches our expectations for this unit. At low ISO sensitivities it produces highly detailed images with decent dynamic range and no visible noise; for the very best results I’d keep the sensitivity at ISO 800 or lower. Step up to ISO 1,600 and 3,200 and images are still very usable, although it should be noted that fine detail does start to suffer visibly. Higher ISO settings aren’t so great, though: I would be happy using ISO 6,400 and perhaps ISO 12,800 for casual web use and small prints, but the extended settings push this sensor too far, and only really give usable results with DxO’s multi-shot SuperRaw mode. But it’s also worth remembering that with the fast f/1.7 lens, such high ISO settings aren’t needed all that often anyway.

Lab Results – Dynamic range & resolution

Dynamic range

We’re accustomed to seeing fine results from the 20.2-million-pixel, 1in sensor in our Applied Imaging tests, and in the DxO One it behaves as well as ever. Dynamic range is excellent through to ISO 400, but starts to fall more quickly at higher settings. By ISO 3,200 we register just 7.5EV, which is rather marginal and indicates loss of shadow detail. The higher settings give poor results, with sub-6EV readings at the top two ISOs rendering them barely usable at all, at least in conventional single-shot-capture mode.

Resolution

At low ISO sensitivities, the DxO One resolves around 3,200l/ph, which is about as high as we’ve seen from this sensor, and confirms the quality of the lens (we shot our resolution test chart at f/2.8). Resolution falls slowly as the sensitivity is increased, dropping to around 2,800l/ph at ISO 1,600 and 2,500l/ph at ISO 6,400, which is still quite respectable. Beyond this, noise has a serious impact on recorded detail, with just 2,000l/ph registered at 
ISO 51,200, even with our high contrast black and white test chart.

Lab Results – Noise

Both raw and JPEG images taken from our diorama scene are captured at the full range of ISO settings. The camera is placed in its default setting for JPEG images. Raw images are sharpened and noise reduction applied, to strike the best balance between resolution and noise.

As usual for cameras with this sensor, the DxO One delivers a combination of excellent detail and low noise at ISO 100. Some fine-grained luminance noise starts to creep in at ISO 400 when viewing images closely, but this will rarely have any impact on prints. By ISO 1,600 we see shadow detail starting to block up, while low-contrast detail blurs away. By the time we reach ISO 6,400, almost all fine detail has been lost and colours have become desaturated, making this usable only for non-critical purposes, such as low-resolution web images. The top two extended settings of ISO 25,600 and ISO 51,200 are barely usable at all, when looking at either the camera’s JPEGs or, as here, DNG files processed through Adobe Camera Raw.

DxO One review – Our verdict

Without doubt, the DxO One is a clever design, and I’ve found it to be a much more satisfactory way of adding an accessory camera to an iPhone than the Wi-Fi connected lens-style cameras I’ve used. With a direct physical connection to the controlling device, operational lag is effectively eliminated, and placing the camera as a rotating module at the end of the phone rather than clipping it onto the front makes for much more comfortable use. The whole experience of selecting and posting your favourite shots 
to social media is pretty seamless too.

There’s nothing to complain about in terms of image quality, either, with the combination of a 1in sensor and fast lens outclassing any smartphone camera. The ability to record raw files to the MicroSD card and process them later only adds to the camera’s appeal. Some photographers may miss the compositional flexibility of a zoom lens, but this is the price you pay for such a small, easily pocketable unit that you can carry all the time.

Despite its undoubted strengths, though, it’s difficult to wholeheartedly recommend the DxO One at this point. The app feels underdeveloped and lacking in features, and the poor battery life is likely to be a serious problem for enthusiast photographers. However, DxO’s commitment to updating the system means that the app should improve quickly, and with any luck the battery life 
will get better too.

Overall, the DxO One is the most practical ‘connected camera’ yet, and has lots of potential for improvement. It’s a really exciting concept, and great for iPhone users who want a better camera that’s easy to carry around, but it’s not quite ready yet to make standalone compact cameras obsolete.

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About DxO

DxO is a French company that’s best known for its imaging software. This includes DxO OpticsPro, a fully featured raw converter that’s based around profiled lens-correction modules; DxO FilmPack, that emulates the look of analogue film; and DxO ViewPoint, for correcting perspective and wideangle distortions. The company also makes the DxO Analyzer image-analysis system, and runs the DxOMark website that assesses the technical image quality of cameras and lenses. It is also a supplier of image signal processors (ISPs) to mobile device manufacturers.