20 MP PureView, Overview, Samples and Comparison
20 MP PureView Camera
20 megapixels camera with other important elements like Carl ZEISS optics and optical image stabilizer on Lumia 930 makes it another Nokia device where the company has not left anything making the stronger camera module into a smartphone.
20 megapixels sensor of size 1/2.5 inch with the 1.12 microns (µm) pixel size, is the BSI CMOS. On the front of it, the 6 element Carl ZEISS lens has a fixed wide aperture f/2.4 along with the Optical Image Stabilization. That’s what resides inside the body. At the outside you get Dual LED flash along side the glass protecting the lens. For people who didn’t like the extra bulge found on the pioneer Lumia 1020, the camera module on the Lumia 930 is flattened to the back surface.
Lumia 930 Camera Specifications
Main camera of Lumia 930 is PureView labeled.
- 20 Megapixels camera sensor with maximum resolution of (5376 px x 3744 px)
- Sensor type: 1/2.5 inch BSI Sensor
- Carl ZEISS Optics,
- 6-element lens, Aperture: f/2.4, Optical Image Stabilization.
- 2x digital PureView Zoom
- Dual LED flash (operating range 3 meter)
Secondary camera on Lumia 930 is just 1.2 megapixels
- HD 1.2 MP wide angle 1280 x 960 pixels
- f-number/aperture: f/2.4
- Video recording, Still image capture, Video call
The smartphone from other manufacturers such as HTC One which has larger pixel size on their sensors to somewhat improve performance in low-light conditions. Nokia, on the other hand took rather another path and introduced larger sensor sizes on smartphones which never have been thought about. In a straight simple way, the larger sensors are used to gain much more light on it which directly reduces the smaller pixels’ poor performance. With a really appreciative ideology, Nokia used the higher-pixel count on its larger sensor to produce high quality images. That’s where Nokia gave its newly technique a name as “PureView”.
Sensor size comparison chart
Can you see the large grey box in the illustration above? that’s the sensor size of entry-level and mid-range DSLR cameras mostly known for having crop sensors. High-end DSLR cameras have full-frame sensors which are even bigger than this and are very expensive in price. APS-C sensor is 1.8 inches in size and can be evaluated to be much bigger in the above illustration as compared to the other sensor sizes. Size of the sensor is one of the few factors which makes images greatly fine and amazing to see in detail. 
When talking about smartphone cameras then Nokia 808 PureView is still in the lead which we believe will not be beaten as to accommodate larger sensor, the phone has to have larger room for the camera module as we have seen in Nokia 808 PureView at the back. The camera has a much larger extruded module on the back, which people actually objected to have on their smartphones. They also didn’t appreciate the Symbian OS running on that machine. This phone had 1/1.2 inches of sensor in size with 41 megapixels and really amazed us with its quality of photos. We still believe that detail in the photos was really impressive. 
Later Nokia brought that huge 41 megapixel sensor on Windows Phone, Lumia 1020 featuring another larger sensor of size 1/1.5 inch which was still 80% smaller than the sensor found on Nokia 808 PureView. You can check the Lumia 1020 Camera review also. But the factor is, Lumia 1020 also had to have some extruded area on the back of it to accommodate the larger sensor. In Lumia 930 there is no extra bulge on the back for 20 MP camera as you can see at the top but still it has got much larger sensor as 1/2.5″ inch which is a little (0.2″) smaller than most point and shoot cameras but larger than common mobile phone cameras and the sensors in the recent iPhone models.
We have seen the original PureView techniques taken from Nokia 808 PureView, then in Lumia 1020 and other high-end Lumia devices. The same approach of pixel binning is present in the Lumia 930. Nokia uses oversampling technique to narrow down the pixels in the hi-res image and makes an ideal 5 megapixels shot having great detail in the image and that’s with impressively reduced digital noise.
Following illustration shows the 20 megapixels full resolution sensor with the functional 4:3 and 16:9 resolutions 4992 x 3744 (18.7 MP) and 5376 x 3024 (16.3) respectively. The pixel oversampling or pixel binning in the Lumia 930 works the same way as it has been in previous camera smartphones since Nokia 808 PureView and Lumia 1020. It combines and averages multiple pixels on the sensor and creates a single pixel from them. Well it obviously reduces the resolution of the image by up to 4 times but it also reduces noise dramatically. In Lumia 930 a 20 MP full resolution image is created but in addition a 5 MP image is also created which actually contains data from the full sensor, hence it produces much better detail with impressively reduced digital noise.
The above process of combining pixels waves off when you use 2x zoom during the shot. It does produce the 5 MP shot covering the field as you zoomed in but it will not have any benefit from the process we talked about. Technically it will be 5 MP crop from the full sensor and will contain equal detail as you will find in the full 20 MP shot. That is what Nokia calls it a loss-less zoom – which theoretically is. Normally a digital zoom is performed cropping a field of view and enlarge it to match the sensor size where it looses extensive detail in the image leaving it just unusable. You must read about it in original PureView concept. We’ll also compare its loss-less zoom with a traditional digital zoom.
Good thing is that the larger sensor of Lumia 930 produces competitive image at all and shoot impressively in low light with the help of Optical Image Stabilization that works easily hand-held when exposure slows down to 1/7th of the second. 
With the real tests however we think the Lumia 1020 did perform better in most situations when we tried, the credit goes to its larger sensor with higher pixel count. But the hardware at that time was not up to the mark which would have supported the 41 MP camera with enough power and Lumia 1020 was found to be much slower in frequent and sudden shooting situations. With the upgraded hardware now, the Lumia 930’s sensor is completely supported. In fact the SoC on the Lumia 930 is Snapdragon 800 which supports 4K video recording and higher frames per second but Lumia 930 only supports 1080p video recording at maximum. That’s also where Windows Phone has to be fast to work with as Android OS has got into that stage of video recording.
In addition to Lumia 930, we took pictures with accompanying devices we had at various times and situations – these included Galaxy Note 3, Nexus 5.
Outdoor (daylight)
Daylight shots were pretty easy for almost every device we had but of course the digital noise was less and the detail was better in the shots taken with Lumia 930. However at some scenes Lumia 930 got the color balance off but it was not something to call as bad image.
Following shots were taken with Lumia 930 (left) and the Galaxy Note 3 (right) just outside my home by chance when it was bright sun on the top. Unfortunately we lost the high resolution shots from Lumia 930 for this test so to compare with 5MP shots from Lumia 930 we down-sampled the Note 3 shots to 5MP.
5MP shot Lumia 930 – 100% crop (Left) – 5MP (down-sampled) Note 3 – 100% Crop
In this comparison, Lumia 930 really did better in getting the detail in the image that you can see in the foliage, which is soft to look at. On the other hand in the shot from Note 3, it’s little over sharpened on the edges and easily can be identified. Secondly, the exposure handling seems to be better in this image from Lumia 930 but when looking closely you can easily see a red tinted area on the background wall which is more accurate on the Note 3 but little highlighted.
Both shots are showing impressively reduced noise but we are looking at the combined pixels detail of 5 MP shot from Lumia 930 as well as soft re-sized photo from Note 3.
Lumia 930’s image is more impressive overall.
Untouched images: Lumia 930 (left) and Note 3 (right)
 |
 |
| Lumia 930 | Note 3 |
Outdoor (daylight)
Following shots were taken with Lumia 930 and the accompanying Nexus 5 right outside our workplace. It was a big Safeda tree (Himalayan poplar) as subject and a wide variety of background elements including fully exposed blue sky with a little bit clouds. The time was just about to have lunch in the mid day with the fully bright sun when I took these shots.
In this shot Lumia 930 again captured a good image with better detail where the Nexus 5 could not keep the detail in shadows. If comparing the full resolution shots from both of the devices, the edges in the Nexus 5 8MP shot are not really clean. On the other side the 18MP shot from Lumia 930 also delivering some noise in dark areas but still keeping the image detail.
Overall the Lumia 930 handled the exposure very well and delivered properly exposed background elements with good blue sky with visible light clouds. In the shot from Nexus 5 was a bit exposed on the background.
Untouched images: Lumia 930 (left) and Nexus 5 (right)
 |
 |
| Lumia 930 – 5 MP 18.7 MP High-res |
Nexus 5 |
Outdoor (daylight)
This is another shot where Lumia 930 gave better result with respect to the detail and the better exposure handling. The color reproduction was found to be better in the image from Lumia 930. Nexus 5 just could not handle the exposure and just create a fully bright image on the foliage while the background sky was also over exposed.
In the high resolution shot Lumia 930 still have some noise but not that bad. However the detail is still impressive.
Untouched images: Lumia 930 (left) and Nexus 5 (right)
 |
 |
| Lumia 930 – 5 MP 18.7 MP High-res |
Nexus 5 |
Outdoor (zoom test)
As Nokia has changed it’s digital zooming feature in its high-end smartphones which they call a loss-less zoom. It’s actually a crop from the sensor. You must have now an idea that how Lumia 930 stores a 5 MP image along with a full high-res image. Also how that 5 MP shot contains an impressive amount of detail in the image which actually is the combination of all the 20 megapixels. When you use the 2x zooming feature in Lumia 930, that impressive detail is lost and you get what the sensor could achieve – which is also much better though. The final zoomed image comes to be a crop from the full sensor. So you
Let’s say it other way around. When you zoom into 2x the field of view on the Lumia 930, it will be captured in the 5 MP shot – as described about a crop from the full sensor. Additionally the high resolution shot will also be stored with a full field of view (without the 2x zoom). Interestingly this feature lets you recompose your field of view after you have taken a shot. It means you can always zoom back out later if you want to. Anyways let’s compare the shots.
In the following picture with crops, you will easily notice that the the top-middle (18.7MP high-res) and top-right (5MP 2x zoom) crops are pretty equal in the field of view – that’s what I mentioned above in the technical note as the zoomed-in image will actually be a crop from the high-resolution image. I have added an actual 5MP field of view (top-left) without zoom from Lumia 930 to compare the result (note that when you are using the zooming feature in Lumia 930, this shot will not be available). When you compare both 5 MP shots from Lumia 930 (top-left and top-right), the zoomed-in image is impressively having the same detail which is actually captured by the full sensor (top-middle)
The bottom row is showing crops from the image from Nexus 5 and undoubtedly the zoomed ones are the traditional digital zoom which seems really unusable comparatively.
Untouched images: Lumia 930 (left full-res, middle 2x) and Nexus 5 (right 2x)
 |
 |
 |
| Lumia 930 – 18.7 High-res | Lumia 930 – 5 MP ~2x Zoom | Nexus 5 – 8MP ~2x zoom |
Indoor (with & without flash)
Next we tried Lumia 930 and the Nexus 5 in a room lit normally with a 40 watt tube light and an energy saver of 24 watts.
When shot without flash, the Lumia 930 intelligently used the possible slower shutter speed with most efficient ISO sensitivity to handle both the light and the camera-shake instances simultaneously where the Optical Image Stabilization also worked great and produced an non-shaky image. On the other hand Nexus 5 does have OIS but I am not sure if it is used during the still image shots. Nexus 5 ended up using a very high ISO sensitivity and losing all detail to a heavy noise and distorted pixels.
With the flash, Lumia 930 used the lowest possible ISO sensitivity and exposure times to produce again an impressive image. Even I could read a bar code on the tooth pick jar. Nexus 5 unexpectedly used higher ISO sensitivity even with a flash-on which still resulted in an unusable image.
However in this test, Lumia 930 add some blue tint with the flash while the Nexus 5 added some yellow but the exposure was well controlled by Lumia 930.
Untouched images: Lumia 930 and Nexus 5
 |
 |
| Lumia 930: 5 MP (Flash-off, Flash-on) 18.7 MP (Flash-off) |
Nexus 5: 8 MP (Flash-off) 8 MP (Flash-on) |
Video Recording:
We have to excuse for that as we could not provide any comparison but according to the tests we performed, Lumia 930 was not any better comparatively. The Optical Image Stabilization however was good on Lumia 930 recordings to bring steady and non-shaky video. Lumia 930 records with the options 1080p and 720p at 30, 25 and 24 fps. In audio recording Lumia 930 supports Dolby Digital 5.1 surround sound with the help of 4 HAAC microphones which, according to the company’s claim, can record up to 140 dB without clipping. Additionally the audio bass filter is what you can set to 100 Hz, 200 Hz or turn it off which can filter out the noises such as engine noise.
Nokia has undoubtedly improved its audio quality in the video recordings by a large margin but it also technically lack features such as 4K (or 2160p) video recording which is now supported on Android devices or on the other hand iPhone 6 supports slow motion video recording up to 240 fps.
