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Review: DxO One
3:00 am | October 9, 2015

Author: admin | Category: Cameras | Comments: None

Review: DxO One

Introduction and features

DXO has a background in creating software for correcting optical and digital imperfections in images. As well as offering desktop software to make these corrections, the company’s technology is found in around 300 million imaging devices – including many popular mobile phones.

DXO is also the company that produces the software that we use to analyse camera performance. This means that it has an in-depth understanding of optics and image quality, as well as how to correct image problems.

As DXO has only produced software to date, it comes as a surprise that it has decided to branch out into camera production. But rather than producing a ‘me-too’ type compact, or adding to the long line of GoPro wannabes, the company has decided to produce a camera that is specifically designed for use with an iPhone or iPad with a Lightning Connector. It also has the level of control that enthusiast photographers want.

DxO One

The DXO One is about the same size as a GoPro Hero 4 without its waterproof housing and it has an internal frame made from aluminium with a half aluminium, half plastic shell to give it a premium feel. Inside is a 1-inch type 20.2-million-pixel backside-illuminated (BSI) CMOS sensor. DXO doesn’t state where it has sourced the sensor from, but it’s pretty clear from the references to the ‘best 20Mp backside-illuminated 1-inch sensor around’ that it has come from Sony.

Lens and sensor

The lens uses an unusual 6 element design with no flange depth (meaning there’s no space between the final element and the sensor), has an equivalent focal length of 32mm and a maximum aperture of f/1.8, making it possible to control depth of field for creative images. This aperture can be closed to f/11 when you need to get a wide area sharp.

The lens also has a closest focusing distance of 20cm but, judging by the hints being dropped by DXO’s representatives, there will be a macro adaptor coming in the near future. There’s a thread around the lens that would allow adaptors to be screwed on.

DxO One

Although there is Wi-Fi technology built-in, this is does not currently operate and there will be a firmware update, probably around Christmas, to activate it. However, the One also has a Lightning Connector to enable it to be connected to an iPhone. DXO has gone down this route for the ease of making a connection and the faster transfer speed. According to DXO, the connector surpasses Apple’s requirements and has been tested to 38,000 actuations. Apparently, it didn’t fail at this point, the engineers just stopped testing.

Once the camera is connected to an iPhone or iPad, DXO’s app opens to allow you to take control of the camera. In addition to a fully automatic setting and a small collection of scene modes, it’s possible to shoot in program, shutter priority, aperture priority and manual exposure mode.

Sensitivity may be set in the native range ISO 100-12,800 with two expansion settings giving the equivalent of ISO 25,600 and 51,200. Shutter speed can be varied between 15 and 1/8,000sec and exposure compensation is available to +/-3EV. There are five preset white balance settings along with an automatic setting and a choice of Full, Centre-weighted and Spot metering.

File formats and video

Images are saved as raw (DNG) and JPEG files with raw files being saved to the microSD card in the camera and JPEGs to either the card or the iPhone as you choose. Another file format, SuperRaw, uses DXO technology and takes four raw images at a rate of 22fps (frames per second) with one press of the shutter release. These images are composited into one raw file that can be edited in DXO Optics Pro (a licence for the Elite version of this software is supplied with the camera). This compositing is claimed to enable greater control over noise and better dynamic range.

While the One is designed with connected shooting in mind, it can shoot in fully automatic mode without an iPhone.

DxO One

As well as stills, the One can be used to shoot 1080p video at 30fps or 720 at 120fps (for slow motion playback) in MOV (H.264) format. However, DXO is keen to point out that the One is aimed at serious photographers rather than action cam users.

The camera comes with DXO Connect, which is used to import and automatically optimise images as well as Optics Pro Elite for bespoke processing and FilmPack for adding creative effects.

Firmware upgrades will be made via the App Store when the camera is connected to an iPhone.

Build and handling

Thanks to its aluminium components, the One has a higher quality feel than a GoPro but it’s about the same size and has a similar number of controls on its body. Interestingly, the One’s size was set to match the iPhone 5 so that in landscape orientation its base aligns with the phone’s. This means that the iPhone 6 extends below the One, but it sits comfortably on a table with the iPhone at an angle for viewing from above.

DxO One

On the front there’s a sliding lens cover and the camera powers-up as this is pushed back. Pushing back the cover a second time releases the Lightning Connector on the side of the camera. This slots into an iPhone and doing so triggers the app to start up provided that the phone is unlocked and on the home page. On top there’s a physical shutter release button with a two stage movement like there is on a traditional camera, but there’s also a virtual button on the iPhone screen. As you’d expect, the phone screen shows icons to access the shooting modes and exposure settings.

The One makes a fairly comfortable small grip on the side of the iPhone, but the phone needs a second hand for support. Different users are likely to hold it in different ways – some may prefer to grip the phone and leave the One hanging; it’s light enough to allow that. If you hold the One, you need to take care to avoid your finger straying over the lens.

While the One may seem a good option for travellers and tourists, it’s actually rather awkward to use when you’re wandering around taking a few shots here and there. It’s not especially convenient to hold it connected to the camera when walking around and if you disconnect it you need to bear in mind that you need to unlock the phone and access the home screen before reconnecting (which can be a little fiddly). In additiion, there’s a short delay after connecting before the camera is ready for use. In the early days of using the camera I missed a few shots because I didn’t anticipate how long it would take to get the One ready for shooting.

DxO One

The Lightning Connector is on a swivelling base and can be rotated through +/-60 degrees for easier screen viewing when shooting at high or low angles, and a clever release mechanism prevents the connector or the phone port from being damaged if the camera is bent back or forwards. This works well. However, I found the degree of rotation available a little restricting when shooting from high or low angles. There were quite a few situations when it would have been helpful to have been able to twist the phone a little further around to give a clearer view.

Another issue is that the Lightning Connector needs to be in its original orientation before it can be folded away. If you disconnect the phone when it’s at an angle you have to reconnect to give the leverage to rotate the connector back to the home position. The lens cover also needs to be pushed down to the release point to enable the connector to be tucked away. It’s quick to release but slow to stow.

Occasionally the connector was popped back in when it was slightly out of alignment (or it somehow was rotated after being packed away when it was in my pocket) and a fingernail was required to prise it out while the release was activated.

It would be nice for the connector swivel base to allow the camera to be rotated into Selfie mode without disconnecting and reconnecting, but I’m told that this would have had a negative impact upon the unit’s durability. If the camera is mounted with the lens facing the same direction as the iPhone screen it automatically actives Selfie mode.

Once in Selfie mode, pressing the shutter release focuses the lens and the iPhone screen turns a bright peach colour just as the shot is taken. This puts warm, soft light on your face to make a more attractive image and to help keep the sensitivity level down in low light so there’s less noise in the shot.

A small touch-sensitive OLED screen on the back of the One indicates the camera settings and when the camera is used in standalone mode it’s used to switch between stills and video mode with a swipe. A dot indicates when the lens has been focused. The camera works in fully automatic mode when it’s in standalone mode, but at some point in the future it’s planned to allow users to use the app to specify how they want the camera to operate when it’s used without an iPhone. It’s tempting to use the One unconnected for speed, but it means composition is guesswork so I wouldn’t recommend it.

DxO One

When the camera is connected, I found it really easy to locate the settings that I wanted and to make adjustments, but there are some inconsistencies in how they are adjusted. When you tap aperture, shutter speed or exposure compensation, for example, a virtual dial appears for you to rotate to the desired setting. Tapping the white balance setting, however, toggles through the options. According to DXO this will be addressed by a firmware update and the white balance setting will be changed using an on-screen dial.

There’s face recognition, but a tap of the screen can also set the focus point just as you would normally with an iPhone. Focus speed is about the same as with an iPhone normally. There were several occasions during this test when the AF area would be displayed on the phone’s screen but it wouldn’t display it if I tapped in another area. On other occasions it was fine for one shot, but wouldn’t allow me to set the AF area for a second shot.

Although the One is essentially an iPhone accessory, it feels well integrated and is easy to use although it takes a little longer for captured images to appear on the screen than it does when using the iPhone camera.

The One’s battery is claimed to last for 220 shots or 90 minutes of video recording (maximum recording time is 29 mins 59 seconds at a time). We found that to be rather optimistic. When using the One out on a shoot around London I got 144 images on a single battery charge despite taking great care to preserve battery power and quickly turning the camera off after shooting. In the lab, taking 150 images reduced the fully charged battery to 20% power. When the power drops to this level or lower we found that the camera can become a bit temperamental and sometimes refuse to start up the shooting mode. If you’re planning to take a series of images over several minutes it can be alarming to see how quickly the battery life slips away and you quickly you need to get into the habit of closing down the camera between shots.

Writing times are also a bit on the slow side and images take a little longer to appear on the screen than when using the iPhone camera.


DXO has used a good quality sensor and it knows how to get good results from a lens, so I wasn’t surprised to discover that the One is capable of capturing a good level of detail. As usual, the raw files (either standard raw or Super raw) look better at 100% than the JPEGS but the differences were more marked in the lab than with most real world images.

Interestingly, the camera gave us a lot of problems in the lab with DXO’s own Analyser software struggling to give us signal to noise and dynamic range measurements for the higher sensitivity settings. We shot and ran the analysis numerous times, but each time it failed to produce results for the upper values.

DxO One sample image

The One has captured a high level of detail and exposure and colour are first rate with this bright scene. Click here for a full size version.

DxO One sample image

JPEG image. Click here for a full size version.

DxO One sample image

Raw image. Click here for a full size version. Both of these images look good but at 100% there’s just a little more detail in the front trunk in the image form the raw file.

In real world images, noise is controlled well at normal viewing and sharing sizes. If you zoom into view high sensitivity images at 100% you’ll see some smoothing between slightly bold edges, but it’s not excessive (or uncommon).

At low to mid sensitivity values there is no noticeable benefit to shooting Super raw images, but as sensitivity reaches ISO 1600 signal to noise ratio is boosted and images are cleaner. The impact upon detail resolution is less clear – sometimes it seems slightly better, other times a little worse. We didn’t see a measurable improvement in dynamic range over standard raw files either.

DxO One sample image

JPEG image: Click here for a full size version.

DxO One sample image

Super Raw image. Click here for a full size version. Sensitivity was pushed to ISO2000 here and the Super Raw file looks more natural, detailed and sharper at 100%. At normal viewing sizes the differences are subtle but visible.

Shooting images with backlit subjects such as leaves against a bright sky reveals that chromatic aberration is controlled well, as is distortion. Colours are also good and the automatic white balance system generally does a good job. The general purpose metering system is a little less consistent, with minor shifts in focus point or framing sometimes causing quite dramatic changes in exposure, which can leave you occasionally adjusting the exposure compensation value backwards and forwards.

On the whole, though, the DXO One produces very good images which are better than you’d expect to get from an iPhone. They also compare well with a decent dedicated compact camera like the Sony RX100 III.

DxO One sample image

Shooting this close subject at f/1.8 has restricted depth of field (the size of the sharp zone) dramatically. I had to dial in 0.67EV negative exposure compensation to get the result I was looking for. Click here for a full size version.

DxO One sample image

DXO is promising to add an electronic level with a firmware update at some point in the future. It would be useful with subjects like this. Distortion is controlled well though. Click here for a full size version.

There were periods during this test where the camera and app performed well, but there were also some frustrating occasions when the app crashed or it wouldn’t show the image across the whole phone screen. With the present incarnation of the app and firmware, it lacks the reliability of a Sony compact camera.

The illumination screen that pops-up at the point of taking a selfie helps the camera produce more flattering results in low light, but there’s a delay after the countdown, which rather defeats the point of the countdown.

Lab tests: DxO One resolution

We ran the DxO One through our usual battery of lab tests, including resolution, dynamic range and signal to noise ratio (noise). We also compared it with four of its chief rivals, which is a little tricky with such an unusual camera – though we have found some interesting alternatives:

Sony RX100 IV: A classic high-end compact camera and a more mainstream choice for photographers who want a carry-anywhere camera. Interestingly, this too has a 20-megapixel 1-inch sensor.

Canon PowerShot G7 X: Canon also uses a 1-inch 20-megapixel CMOS sensor it its smallest PowerShot model.

Panasonic CM1: The DxO One’s claim to fame is that it lets you shoot with a big 20-megapixel 1-inch sensor and your iPhone – but the Panasonic CM1 is a phone with the same sensor specs built in.

DxO One resolution charts

DxO One lab test charts

JPEG resolution analysis: Disappointingly, the DxO One’s JPEG images deliver a little less resolution than those from its rivals. It looks as if you need to shoot raw files to get the sharpest detail – see the chart below.

DxO One lab test charts

Raw (converted to TIFF) resolution analysis: When shooting raw files the DxO one delivers results on a par with those from the Sony RX100 IV, Canon G7 X and Panasonic CM1.

Lab tests: DxO One dynamic range

Dynamic range is a measure of the camera’s ability to capture scenes with a very wide brightness range without losing detail in the brightest or darkest areas. We use DxO Analyzer test equipment to measure dynamic range in laboratory conditions.

DxO One dynamic range charts

DxO One lab test charts

JPEG dynamic range analysis: Just as it did in the JPEG resolution test, the DxO One produces slightly disappointing results here, too, lagging behind the Sony RX100 IV, Canon G7 X and Panasonic CM1.

DxO One lab test charts

Raw (converted to TIFF) dynamic range analysis: Again, the DxO One delivers its best results when you shoot raw files. This time it beats all its rivals, though the gap closes by ISO 800. At lower ISOs its dynamic range is very good, and similar to that you’d expect from DSLRs or compact system cameras with much bigger sensors.

Lab tests: DxO One signal to noise ratio

A camera’s signal to noise ratio is a good indicator of how ‘noisy’ its images are at different ISO (sensitivity) settings. The higher the signal to noise ratio the better, because that means the camera is capturing more actual image data and less random noise. Our figures are measured using DxO Analyzer in laboratory conditions.

DxO One signal to noise ratio charts

DxO One lab test charts

JPEG signal to noise ratio analysis: The DxO One’s JPEG images are very much in the middle of the pack for noise levels at most ISO settings.

DxO One lab test charts

Raw (converted to TIFF) signal to noise ratio: Again, the DxO One’s results are very close to those of its rivals – though the Canon G7 X does seem to have a clear noise advantage at low to medium ISO settings.


The DXO One is a very small camera that can be carried in the pocket of your jeans, yet has a 1-inch type sensor like the ones found in some of the best compact cameras. It also has a large maximum aperture and an equivalent focal length that’s close to the classic street photographers’ favourite (35mm). In addition, it’s easy to connect it to an iPhone and can be used with any iOS device that has a Lightning Connector, so it effectively has a very high quality touch-screen. It’s also easy to use and gives photographers full control over exposure.

DxO One connection

However, in practice it can be a pain to use as a replacement for a regular camera and you find yourself fiddling about unlocking your iPhone, ducking out of email or trying insert the connector quickly when you really want to be just flicking a power switch and pressing the shutter release. It can be used without the phone but it operates in automatic mode and the lack of a built-in screen means that composition is guesswork.

We liked

The beauty of DXO’s approach to connecting the One to an iPhone physically is that there’s no waiting about for a Wi-Fi connection and it won’t lose the connection. The camera also fits almost seamlessly into the operating system and images can be stored on your phone – plus there are raw files on the card if you want them for post-processing. It also means that you can use any of your favourite apps to apply effects and it’s very easy to share images to your preferred social media sites or by email.

We disliked

While the One’s connectivity is its strength it’s also a weakness. You have to remember to unlock your phone or go to the home page before you connect the One in order for the app to open correctly and then there’s a second or two delay before you can start shooting. A dedicated camera would be ready in less time.

There are also a few bugs in the system and we had several occasions where the camera or app crashed or it wouldn’t return to shoot mode after being asleep for a short period. These are issues that DXO is likely improve with firmware upgrades – as well as add new features like a digital level – but for now they can be an issue.


At the outset of this test I was pretty excited about using the One, but by the end I was less enthusiastic. It may be small, easy to connect and offer lots of control, but I’d rather use a traditional camera that is ready for use within a second of it being pulled from my pocket, is easier to use when on the move and has better battery life.

However, the One produces great quality images for a compact camera and it makes a fun, if expensive iPhone accessory. If you’re looking for a very compact device to enable you to take better images with your iPhone (with a Lightning Connector) then it’s a good option. However, if you’re looking for a compact camera you are better off with something like the Sony RX100 II or Canon G7 X.

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