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DxOMark Mobile Report: Sony Xperia Z2

With a DxOMark Mobile score of 79 the Sony Xperia Z2 is the current number two in the DxOMark smartphone rankings, behind Samsung's Galaxy S5 and in front of the Nokia 808 and its own predecessor, the Xperia Z1

The DxOMark team reports the Xperia Z2 images show "impressive detail preservation outdoors" and "in low light, a lot of detail is still visible, even if a loss of details is noticeable compared to outdoors." Noise levels are reasonable at all light levels, with small grain size and no chroma noise. The autofocus works in a fast and responsive manner, with only very few focus errors. The DxO team found the Z2 to deliver "good overall exposure," "nice colors in all conditions" and a "good overall flash performance."

On the downside, DxO says the "white balance is sometimes unstable indoors" and "outdoors, some images show a slight blue cast." They also report "slight color shading is also noticeable under tungsten light." Aside from the white balance issues the Z2 images show "noticeable fringing, ringing (haloing around high-contrast edges) and maze artifacts."

In video mode the Xperia Z2 displayed "good stabilization, especially on walking movements, good texture reproduction and low noise levels." However, the "autofocus moves step-by-step rather than continuously, and is unstable." DxO has also found "white balance failures on vegetation scenes under daylight illuminant, visible color shading and aliasing."

Still Photography

Color, Exposure and Contrast

The DxOMark team found that the Sony Xperia Z2 images show "good overall exposure and nice colors" and "in extreme low light conditions, images are better exposed than most other camera phones." The DxO testers also noticed the exposure adapts intelligently to the scene or shooting conditions - for example when shooting portraits or mounting the Z2 on a tripod. 

However, DxO also found "contrast is not very good in shadows, white balance is slightly cold outdoors" and there is "slight color shading noticeable under tungsten light."

Overall DxOMark awarded the Sony Xperia Z2 scores of:

  • 4.5 out of 5 for Exposure
  • 4.0 out of 5 for White Balance accuracy
  • 3.5 out of 5 for Color shading in low light*
  • 4.0 out of 5 for Color shading in bright light*
  • 3.0 out of 5 for Color Rendering in low light
  • 4.5 out of 5 for Color Rendering in bright light

*Color Shading is the nasty habit cellphone cameras have of rendering different areas of the frame with different color shifts, resulting in pictures with, for example, pinkish centers and greenish corners.

Noise and Details

DxOMark's engineers reported the Sony Xperia Z2 shows "impressive detail preservation outdoors" and in this respect is "one of the best smartphones tested to date." In the Z2 image output "noise is only in the luminance channel and the grain is small." Good detail is maintained in low light (20 lux) but a slight reduction is noticeable. 

Texture Acutance

Texture acutance is a way of measuring the ability of a camera to capture images that preserve fine details, particularly the kind of low contrast detail that can be blurred away by noise reduction or obliterated by excessive sharpening (such as fine foliage, hair or fur).

Sharpness is an important part of the quality of an image, but while it's easy to look at an image and decide visually whether it's sharp or not, the objective measurement of sharpness is less straightforward.

An image can be defined as "sharp" if edges are sharp and if fine details are visible. In-camera processing means that it's possible to have one of these (sharp edges) but not the other (fine details). Conventional MTF measurements tell us how sharp an edge is, but have drawbacks when it comes to measuring fine detail preservation. Image processing algorithms can detect edges and enhance their sharpness, but they can also find homogeneous areas and smooth them out to reduce noise.

Texture acutance, on the other hand, can qualify sharpness in terms of preservation of fine details, without being fooled by edge enhancement algorithms.

A dead leaf pattern is designed to measure texture acutance. It's obtained by drawing random shapes that occlude each other in the plane, like dead leaves falling from a tree. The statistics of this model follow the distribution statistics in natural images.

In this example from a DSLR without edge enhancement, sharpness seems equal on edge and on texture. Many details are visible in the texture.

In this second example, edges have been digitally enhanced, and the edge looks over sharp, with visible processing halos ("ringing"). On the texture part, many details have disappeared.

At first sight, the images from these two cameras may appear equally sharp. A sharpness measurement on edges will indeed confirm this impression, and will even show that the second camera is sharper. But a closer examination of low contrasted textures shows that the first camera has better preservation of fine details than the second. The purpose of the texture acutance measurement is to qualify this difference.

Note: Acutance is a single value metric calculated from a MTF result. Acutance is used to assess the sharpness of an image as viewed by the human visual system, and is dependent on the viewing conditions (size of image, size of screen or print, viewing distance). Only the values of texture acutance are given here. The measurements are expressed as a percentage of the theoretical maximum for the chosen viewing condition. The higher the score, the more details can be seen in an image. 
 
For all DxOMark Mobile data presented on connect.dpreview.com we're only showing 8MP equivalent values, which gives us a level playing field for comparison between smartphone cameras with different megapixel values by normalizing all to 8MP (suitable for fairly large prints). DxOMark also offers this data for lower resolution use-cases (web and onscreen). For more information on DxOMark's testing methodology and acutance measurements please visit the website at www.dxomark.com.
Luminance texture acutance is similar under daylight and tungsten light and increases to high levels as the illumination becomes brighter. 
In terms of texture acutance, the Xperia Z2 lags slightly behind the Nokia 1020 at low light levels but takes the top spot in brighter conditions. 
Edge Acutance
Edge acutance is a measure of edge sharpness in images captured by the phone's camera. Again we're only looking at the most demanding of the three viewing conditions that DxOMark reports on - the 8MP equivalent.
In terms of edge acutance the Sony Xperia Z2 leads the pack at all light levels. 
The Sony Xperia Z2's ability to retain sharp edges is excellent across all light levels. 
Visual Noise

Visual noise is a value designed to assess the noise in an image as perceived by the human visual system, depending on the viewing condition (size of image, size of screen or print, viewing distance). The measurements have no units and can be simply viewed as the weighted average of noise standard deviation for each channel in the CIE L*a*b* color space. The lower the measurement, the less noise in the image.

Noise levels in daylight conditions are low across all light levels.
Noise levels under tungsten light are a touch higher than in daylight conditions.
The Sony Xperia Z2's noise levels are among the lowest at all light levels. 

Noise and Detail Perceptual scoring

DxOMark engineers don't just point camera phones at charts, they also take and analyze scores of real-world shots and score them accordingly. Their findings for the Sony Xperia Z2 were:

Natural scene

  • Texture (bright light): 5.0 out of 5
  • Texture (low light): 3.5 out of 5
  • Noise (bright light): 3.8 out of 5
  • Noise (low light) 3.8 out of 5
Bright light sample shot. 
100% crop: A lot of fine detail is visible in the Z2 images.
Low light (20 Lux) studio shot.
100% crop: Detail is still good but has been slightly smoothed over by noise reduction.  
100% crop: Luminance noise is visible but the grain size is pleasantly small.

Artifacts

Phone cameras, like entry-level compact cameras, tend to suffer from artifacts such as sharpening halos, color fringing, vignetting (shading) and distortion, which can have an impact on the visual appeal of the end result. DxOMark engineers measure and analyze a range of artifacts. Their findings after testing the Sony Xperia Z2 are shown below:

  • Noticeable fringing outdoors
  • Strong ringing
  • Some flare in challenging light situations
  • Maze artifacts

Perceptual scores

  • Sharpness 4.0 out of 5
  • Color fringing 4.0 out of 5

Measured findings

  • Ringing center 22.6%
  • Ringing corner 16.0%
  • Max geometric distortion 0.2%
  • Luminance shading 25.1%

Distortion and Chromatic Aberrations

The graph shows the magnification from center to edge (with the center normalized to 1). The Sony Xperia Z2 shows slight pincushion distortion, which you are not going to notice in normal photography.
The Xperia Z2 shows some lateral chromatic aberrations which is slightly visible in some pictures.

Autofocus

DxOMark also tests autofocus accuracy and reliability by measuring how much the acutance - or sharpness - varies with each shot over a series of 30 exposures (defocusing then using the autofocus for each one). As with other tests these results are dependent on the viewing conditions (a little bit out of focus matters a lot less with a small web image than a full 8MP shot viewed at 100%). Using the 8MP equivalent setting, the Sony Xperia Z2 is quite a bit better than its predecessor, the Xperia Z1. The overall score is 87/100 in bright light and 81/100 in low light.

Pros: 

  • Fast and reactive autofocus
  • Good overall repeatability and precision

Cons: 

  • n/a
Autofocus repeatability - average acutance difference with best focus: low light 2.36%, bright light 5.50%

Flash

DxOMark scored the Sony Xperia Z2 85/100 overall for its flash performance which is one point more than the Xperia Z1.

Pros: 

  • Precise autofocus, good exposure, good color rendering and white balance, good detail preservation

Cons: 

  • White balance slightly inaccurate in when mixing flash with tungsten light
  • Some noise
  • Slight vignetting

Overall DxOMark Mobile Score for Photo: 81 / 100


Video Capture

DxOMark engineers put phone cameras through a similarly grueling set of video tests, and you can read their full findings on the DxOMark website here. Bottom line: DxOMark found the Sony Xperia Z2's overall video performance to be good,  with decent stabilization, nice textures and low noise levels. However, the AF tends to be a little unstable and white balance can be unreliable in some shooting situations. 

Pros: 

  • Good stabilization, especially on walking motion
  • Good texture reproduction
  • Low noise level

Cons: 

  • Autofocus moves step-by-step rather than continuously, and is unstable
  • White balance failures on vegetation scenes in daylight
  • Visible color shading

Overall DxOMark Mobile Score for Video: 73 / 100

Comments

Total comments: 37
oznikonian

Lars just letting you know the camera app on my Z2 remembers the mode you were in last.(selecting the camera icon on the home screen) its only when you use the button to launch the app that it reverts to the Superior Auto mode.

1 upvote
Peiasdf

Poor showing for the level of hardware this phone is carrying.

0 upvotes
ageha

The phone will be obsolete in a few days.

0 upvotes
Lars Rehm

for the past couple of years or so Sony has been replacing its top-of-the-line model every 6 months. However, that does not mean the previous model is not available for purchase anymore. You'll be able to buy a Z2 for quite some time. Equally, whatever gets announced at IFA most likely won't be available in the shops straightaway.

0 upvotes
ET2

where are studio shots?

1 upvote
Yudi Hilmawan

Next time it would be much better if you just can show us image comparison tools like comparometer from the imaging resource other than this kind of review.
I'm really disappointed with your review because even some other non photography related site can provide us with more better and detailed review.

1 upvote
Lars Rehm

can you specify where we find those great reviews from non-camera people? Just so I can have a look.

2 upvotes
BarnET

Lars you gave an Sony phone an good review.
For some that is enough reason to call you all sorts of things.

0 upvotes
Toshik

Why would cameras need to crank up iso while using flash? Flash helps to illuminate the subject and therefore lower iso as there is more light.

0 upvotes
Lars Rehm

part of the problem is that most smartphones don't have real flash units but tiny LEDs which do not nearly produce the illumination of a Xenon flash.

1 upvote
vlad0

No studio shots ?

1 upvote
eno2

Sony cameras have the most unpleasant jpg engine from all companies that I know of, this phone make no exception. The heavy NR + heavy sharpening applied in the photos make the unusable. It is very sad.

3 upvotes
Menneisyys

I wish they had RAW output. (Not that I would purchase these phones... Sony is one of the worst companies WRT phasing out their "old" models - about every half a year. In this regard, all major manufacturers are better - Apple, LG, Samsung, Nokia/MS etc.)

3 upvotes
bigley Ling

Yes, but the Z2 does seem to improve the JPG engine to a degree, as there seems to be less heavy handed noise reduction. That being said, images at higher ISOs still lack detail, and are indeed noisy.

0 upvotes
bigley Ling

Menneisyys , I think the android phone that has RAW output currently is the OPPO find 7.

0 upvotes
Menneisyys

"Menneisyys , I think the android phone that has RAW output currently is the OPPO find 7."

Nevertheless, Sony has always put a LOT of emphasis on the cameras of their phones. I would really like them to give their customers RAW. After all, it can't be THAT hard to implement (unless they use some kind of a chipset where there's absolutely no access to the sensor data w/o preprocessing / JPEG compressing first.)

0 upvotes
bigley Ling

@Menneisyys

Absolutely agree. It could well be the output from their sensor is not all that it is made out to be, and the need for clever image processing may have been required give a semi descent output.

1 upvote
new boyz

You haven't seen Lenovo's yet. Its IQ(or lack thereof) makes you wanna give up on taking picture.

Comment edited 16 seconds after posting
0 upvotes
Markol

Looking at the samples my first thought is: if your camera can't handle 20 MP, don't even bother to make them available. Just offer the downsized versions, who will benefit from so lousy 20 MP photos?
Maybe it's my eyes or personal taste but the Sony 20 MP smart phones really disappoint big time. And I'm so waiting for a decent Android camera phone. Other than the S5. Nokia 808 decent. Look at the full size images from the 808 and then look at the 20 MP images here- this is my gold standard and not even the 1020 came close IMHO:
http://img230.imagevenue.com/img.php?image=436190887_2013_07_14_2952_122_424lo.jpg

Just to be clear_ I don't doubt that downsampliong these photos will give good results but I wonder why they use such a bad 20 MP sensor, just look at the ISO 50 photo of the roofs with antennae.

Comment edited 3 minutes after posting
2 upvotes
Menneisyys

Absolutely agreed. The 808 is and still remains the stills IQ king. You need to carry around significantly larger & more expensive cameras to produce photos with equal or better pixel-level sharpness.

For example, my 16 Mpixel Fuji X-E1 with its 18-55 lens operating at one of its sweet spots, f/5.6 at 18mm, delivers appr. the same pixel-level detail level. (Its DR, noise, OIS, contrast etc. are significantly better, of course.) Even DSLR cameras with worse lens / lens not operating at their sweet spot / with an AA filter may produce worse results than the 808 WRT detail.

Comment edited 27 seconds after posting
3 upvotes
vlad0

808 is in a different league when it comes to IQ.. Sony are still struggling to get to N8 IQ levels.

0 upvotes
bigley Ling

vlad0 , agree completely, the n8 has abnormally large micron pixels which help contribute to good dyanmic range and lower noise. The only gripe I had with the n8 was the whole camera interface experience. It was good when it was released, but once I got the taste of the 808 camera UI, the n8 controls paled in comparison and actually got annoying to use.

0 upvotes
vlad0

@bigley, yes.. I think they messed up the UX with the "anna" update. I still have mine...its a pretty good smartphone.

The pixels on it are at 1.75 microns I believe.... so I am not 100% sure but I think it still has the largest physical pixels of any smartphone camera out there.

If the rumors are true, and my math is right, the iPhone 6 will finally surpass it with 1.9µm pixels... can't wait to see Apple's marketing frenzy behind "big pixels" vs. megapixel count :)

Comment edited 38 seconds after posting
0 upvotes
bigley Ling

exciting stuff, this IPhone 6. Will wait in great anticipation for it's release and camera offerings. Ignoring the camera quality, I still will be upgrading to an IP6 as I enjoy the way iOS as an operating system works in general

1 upvote
Menneisyys

The iPhone6 will be a major release. For example, the sweep pano implementation has always one of the best in iPhones - and is orders of magnitude better than that of Sony (or, for that matter, Google in their stock Camera app). The only problem with iOS8 is that it still lacks any kind of RAW output.

1 upvote
thx1138

Crazy generous score. The photo IQ is simply second rate at any thing other than viewing it on the phone itself. I'm sure it's a relative score and only compared to other phones but the score is crazy. I reckon DxO would rate this better than a 5D III sensor.

3 upvotes
Lars Rehm

pixel-level image quality is one component of the score but there a other things the X2 is pretty good at, that's how we get to this score.

0 upvotes
ukkisavosta

Thanks for the interesting review. Might I suggest one additional but very crucial item to your testing scenarios: camera lens scratch resistance.

A good camera is useless on a phone, if the lens scratches easily, and my experience with Sony isn't exactly rewarding in this sense.

I recently upgraded my trusty old Nokia N8 to a Sony Xperia SP, and after a couple months of light use (with the phone protected by a fleece-lined case) the camera lens is full of microscopic scratches that have rendered the camera basically useless -- all shots are soft with an ugly glow and the camera struggles to AF.

I've handled the phone very carefully and it is still in like-new condition, except for the lens, which is obviously made of some sub-par glass (or plastic even!). My N8's lens was scratch-free after 3 years of hard use.

I like Sony's products, and I've been happy with my A7 and NEX-C3 cameras, but the Xperia SP has definitely been a disappointment in this respect.

2 upvotes
Lars Rehm

Personally I have not had any problems of this kind with the phones I have tested and I have a feeling that the manufacturers would not be too happy about me deliberately scratching their test units. However, if it happened during normal use in the testing process I would certainly mention that in the review.

1 upvote
ukkisavosta

Ah, too bad, but I perfectly understand.

I'm amazed that these units passed the manufacturers' (or Sony's in this case) scratch resistance tests during the design stage. Surely such basic tests are part of the basic testing process.

Anyway, just wanted to raise this issue to others looking at buying a Sony phone. I'm quite peeved about this and still debating whether to send my Xperia in for a warranty fix (problem would likely turn up again later, or more likely I'd be accused of 'incorrect handling' and charged for the job).

Caveat emptor!

1 upvote
Lars Rehm

well, it's worth a try I would say!

0 upvotes
ipecaca

I have an xperia ION lte and the camera became useless because of the scrached lens in about 3 months as well.

1 upvote
Menneisyys

Yuck. Sounds awful. I won't be recommending Sony smartphones to friends, then. (So far, I've told them to go for them if they like flashy and, most importantly, water resistant stuff.)

1 upvote
dbo

"...only 1080p.."
ONLY????
Cmon, it's a cell phone. Who does really want and/or need 4k in a cell phone?

1 upvote
Lars Rehm

are you talking about the special mode output at 1080p? Yes, that is indeed a small image size for a smartphone in 2014, especially a high-end unit.

0 upvotes
Johannes Zander

What! No PSAM dial... No articulated screen... No hot shoe to mount standart flashes...
I think I keep my D800, also the pohone part is very badly implemented.

0 upvotes
noirdesir

Not that the D800 would have a PSAM dial or articulated screen.

1 upvote
Total comments: 37
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