Image Quality & Performance

With its Qualcomm Snapdragon 800 processor and 2GB RAM the Sony Xperia Z1 is certainly no slouch in the performance department and in general use the Z1 is as responsive as you would expect when looking at the spec sheet. Even the most demanding applications that you can throw at a smartphone, such as 3D games, open quickly and run smoothly. We were also impressed by the Sony's battery life. Even after a long day with heavy use there would still be juice in the 3000mAh battery for another few hours. Most other phones we've tested before would hardly make it through the day with heavy use.

The Z1 is also very quick to get ready for taking pictures. It takes under 2 seconds to open the camera app from sleep mode by long-pressing the shutter button. You can already press the button while the device is still in your pocket which means by the time you hold it in front of you to frame a shot you're ready to press the shutter. Opening the camera app via its icon on the home screen takes about a second.  

Shot-to-shot times are not lightning fast but at 0.5 sec in good light should be enough for most smartphone users. However, focus speed decreases very noticeably to more than 1.0 sec in lower light. Very occasionally the Z1 also captures a out-of-focus image despite a locked focus. Most of the affected images were taken in low light and with flash.   

Daylight, Low ISO

The Sony Xperia Z1's exposure is usually spot on in most lighting situations. In common with most other camera phones colors are a little more saturated than in real life, but the auto white balance function does an efficient job under both natural and artificial light.

So while the Sony Xperia Z1's images look pleasant enough at screen size a few problems become apparent when you zoom in further. The lens is quite sharp in the central areas of the frame and in its 20.7MP mode the Sony can capture a lot of detail there but close up the image output has a very processed and over-sharpened look. You'll find stepping artifacts and a good dose of grain in areas of plain color.

Toward the edges of the frame our sample showed distinctive signs of softness which, in combination with the processing artifacts mentioned above, can make pixel-peeping on the Z1 more unpleasant the further you move away from the center of the frame. 

In good light the Sony captures images with good exposure and color but under closer scrutiny the Z1 cannot translate its large sensor area into cleaner images.  

ISO 50, 1/1250 sec
20.7MP images show decent detail but images look a little over-sharpened and over-processed at a 100% magnification.
100% crop
ISO 50, 1/800 sec
Lens sharpness is excellent at the center of the frame ...
100% crop
ISO 64, 1/2000 sec
... but our test sample suffers from quite strong corner softness.
100% crop
ISO 64, 1/2500 sec
Noise and artifacts are visible in areas of plain color, even at low sensitivities.
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ISO 50, 1/800 sec
Low contrast detail is being smeared, even at base ISO.
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ISO 64, 1/50 sec
The Z1 captures natural skin tones in daylight.
100% crop

Low Light, High ISO

With its fast F2.0 lens and ISO climbing as high as ISO 1000 in its 20.7MP mode the Sony Xperia allows you to capture images with good exposure, even in very low light. There is no optical image stabilization system on the Z1, so at some point the slow shutter speeds create an increased risk of camera shake but on the other hand the physical shutter button helps keep things steadier than when tapping a virtual button on the screen. 

At a 100% view we see the same imperfections as in the bright light samples above. There is a lot of noise and artifacts in the Sony images and it increases as the sensor sensitivity goes up. That said, most noise is of the grainy kind which we are much more willing to tolerate (presumably because we're used to it from the good old film days) than the "digital" chromatic noise. As you would expect the noise is accompanied by decreasing levels of fine detail as it is being smeared by noise reduction. 

Despite the noise and noise reduction edge definition, saturation and exposure remain good throughout the ISO range. So while the Sony's high ISO output struggles to withstand close scrutiny it's more than suitable for online sharing and screen size viewing.

ISO 64, 1/32 sec
With its fast F2.0 lens the Z1 can keep the ISO low even indoors.
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ISO 400, 1/32 sec
There's plenty of luminance noise at ISO 400 but no chroma noise or banding.
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ISO 640, 1/32 sec
Fine detail is suffering but edges are still well-defined.
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ISO 800, 1/20 sec
There's a lot of luminance noise in this image but its grainy appearance makes it much more tolerable than chroma noise.
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Flash

With their tiny LEDs flash performance tends to be one of the weak points of all smartphone cameras. The Sony Xperia Z1 is no exception which means it has to crank up the ISO quite a bit when taking flash images. As a result of this close up the images reveal a lot of noise and loss of detail, just like the high-ISO samples above.

Exposure and white balance tend to be good though. On the Z1 you have a little more control over the flash function than on most smartphones. Apart from the usual flash auto/on/off settings there are separate settings for the anti-red-eye mode, fill-flash and for use of the LED as a torch. Nevertheless those users who are planning to take many flash pictures are much better off with a device that offers a Xenon flash, such as the Nokia Lumia 1020.

ISO 500, 1/32 sec
Flash exposure is decent but the LED flash means ISO has to be cranked up.
100% crop
ISO 500, 1/32 sec
The AF struggles occasionally in low light which can lead to out-of-focus flash images, despite a focus-lock.
100% crop

8MP images

Its 20.7MP maximum resolution is one of the Sony Xperia Z1's marketing headlines but looking at the images output, it might be more sensible to set the camera to 8MP which is the resolution in the default Superior Auto mode anyway.

Even in the best of conditions you only sacrifice a minimum amount of detail and noise, and artifacts are much less prominent when viewing images at a 100% magnification. As a bonus the smaller files need less storage and you can use scene modes, HDR and ISO 1600 and 3200, all of which are not available at 20.7MP. 

ISO 50, 1/50 sec
There are fewer artifacts and less noise in the smaller images.
100% crop
ISO 50, 1/1250 sec
Corner softness is still very noticeable at the lower resolution.
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ISO 320, 1/100 sec
At ISO 320 there is some grain but no chroma noise and still decent detail.
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ISO 1000, 1/40 sec
This image is grainy but again chroma noise is well controlled.
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ISO 2500, 1/125 sec
Detail suffers a lot which at very high ISO settings which means they are best avoided.
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