Nokia 808 PureView

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Nokia 808 PureView
Nokia 808 PureView front and back view.JPG
Manufacturer Nokia
Predecessor Nokia N8
Successor Nokia Lumia 1020
Dimensions 123.9 mm (4.88 in) H
60.2 mm (2.37 in) W
13.9 mm (0.55 in) D
17.95 mm (0.707 in) Bulge
Weight 169 g (6.0 oz)
Operating system Nokia Belle Feature Pack 1, upgradeable to Nokia Belle Feature Pack 2
CPU 1.3 GHz Texas Instruments 4377622 ARM11 processor[1]
GPU Broadcom BCM2763 with OpenVG 1.1 and OpenGL ES 2.0 support.[2][3]
Memory 512 MB RAM
Storage 16 GB on-board memory
Removable storage microSD up to 128 GB supported w/ microSDXC support
Battery Li-Ion; BV-4D 1400 mAh 3.8 V
Display 4-inch AMOLED 2.5D curved nHD display (640x360 pixels)
Gorilla glass with easy-clean coating
Rear camera 41 Mpx (1/1.2-inch) sensor
Carl Zeiss Optics
F-number: f/2.4
ND filter
Xenon Flash
LED video light
1080p 30 fps video with Continuous AutoFocus
Front camera 0.3 Mpx; 480p 30 fps
Connectivity Bluetooth 3.0
Wi-Fi 802.11 b/g/n
DLNA
Micro HDMI
Micro USB
USB On-The-Go
Secure NFC
3.5 mm audio connector with TV-out
FM transmitter
GPS with A-GPS
Band I (W-CDMA 2100)
Band II (W-CDMA 1900)
Band IV (W-CDMA 1700)
Band V (W-CDMA 850)
Band VIII (W-CDMA 900)
GSM 850 / 900 / 1800 / 1900 [4]
Development status Out of production
PureView Pro Sensor with image circle and the 16:9 and 4:3 image areas

The Nokia 808 PureView is a smartphone from Nokia, unveiled on 27 February 2012 at the Mobile World Congress. It runs on Symbian Belle operating system. It is the first smartphone to feature Nokia's PureView Pro technology, a pixel oversampling technique that reduces an image taken at full resolution into a lower resolution picture, thus achieving higher definition and light sensitivity, and enables lossless zoom.[5][6] It was the most advanced camera phone when released in May 2012.

It features a 41-megapixel 1/1.2-inch (10.67 mm × 8 mm) sensor and a high-resolution f/2.4 Zeiss all-aspherical 1-group lens. The 808's sensor to date remains the largest (over 4 times larger than typical compact cameras) and highest resolution sensor ever to be used in a cameraphone, a record previously held by Nokia's N8.[7]

The 808 won the award for "Best New Mobile Handset, Device or Tablet" at Mobile World Congress 2012,[8] and the award for Best Imaging Innovation for 2012 from the Technical Image Press Association.[9] It was also given a Gold Award by Digital Photography Review.[10]

On January 24, 2013, Nokia officially confirmed the 808 Pureview to be the last Symbian smartphone.[11] In July 2013, Nokia released the Lumia 1020, a successor running the Windows Phone operating system common to Nokia's newer products.

PureView Pro camera[edit]

PureView Pro is an imaging technology used in the Nokia 808 PureView device. It is the combination of a 1/1.2-inch large,[12] very high resolution 41 Mpx image sensor with high-performance Carl Zeiss optics. The large sensor enables pixel oversampling, which means the combination of many sensor pixels into one image pixel. PureView imaging technology delivers high image quality, lossless zoom, and improved low light performance (see below). It dispenses with the usual scaling/interpolation model of digital zoom used in virtually all smartphones, as well as optical zoom used in most digital cameras, where a series of lens elements moves back and forth to vary the magnification and field of view. In both video and stills, this technique provides greater zoom levels as the output picture size reduces, enabling 4x zoom in full HD 1080p video, 6x lossless zoom for 720p HD, and 12x zoom for nHD (640x360) video.

PureView Pro specifications[edit]

Sensor
Nokia 808 has a 41.3-megapixel CMOS FSI image sensor, 1/1.2-inch image sensor format with 7728 x 5368 pixels. Depending on the aspect ratio chosen by the user, it will use 7728 x 4354 pixels (33.6 Mpx) for 16:9 images, or 7152 x 5368 pixels (38.2 Mpx) for 4:3 images when using the default camera software. The commercial app CameraPro[13] can use the whole sensor size for capturing full 7728 x 5368 pixels (41.48 Megapixel) pictures with more than 30 Megabytes each. Pixel size is 1.4 µm. Sensor size is 10.67×8.00 mm. Crop factor 3.2×. 35 mm equivalent focal length: 26 mm, 16:9 | 28 mm, 4:3. f/2.4
Compare
Nokia Lumia 1020 has a 41.3-megapixel BSI CMOS image sensor, 1/1.5-inch (2/3-inch) image sensor format with a total of 7712 × 5360 pixels. Maximum image size at a 4:3 aspect ratio is 7136 × 5360 pixels (38.2 Mpx); maximum image size at a 16:9 aspect ratio is 7712 × 4352 pixels (33.6 Mpx). Pixel size is 1.12 µm. Sensor size is 8.80×6.60 mm. Crop factor 3.93×. 35 mm equivalent focal length: 25 mm for 16:9, 27 mm for 4:3. f/2.2
Lens
Carl Zeiss optics with F-number: f/2.4. Focal length: 8.02 mm: 35 mm equivalent focal length: 26 mm @ 16:9 and 28 mm @ 4:3. Construction: 5 elements in 1 group. All lens surfaces are aspherical, partly extreme aspheric,[14] one high–refractive index, low-dispersion glass mould lens.
Focus range
15 cm – Infinity (throughout the zoom range).
Shutter
Mechanical shutter with short shutter lag[15] and ND8 (3 f-stops) neutral density filter
Processing
On-chip image processor performing image scaling with oversampling, giving lossless (optical) zoom: 4x for full HD 1080p video with on-chip video processor performing image resolution processing with over 1 billion pixels per second[15] enabling the use of all pixels for improved image noise and dynamic range.

Image sensor[edit]

PureView Pro sensor has an active area of 7728 x 5368 pixels, totalling over 41 Mpx. What happens after the shutter is depressed depends on the settings and whether or not zoom is used. But to give an idea, the default still image setting is 5 Mpx at 16:9, and for video, 1080p at 30 FPS. Using these settings, the zoom is around 3x for stills and 4x for video. Conventional digital zoom tends to scale up images from a relatively low resolution, resulting in poor image quality.

The image sensor is capable not only of delivering parts of its pixels, but of down- or oversampling its resolution by having its own on-chip image processor, highly reducing external processing needs and data rates as well as image noise (see noise shaping) when lower resolutions (or HD video) are needed. Additionally this provides very high image resolution. Images up to 38 megapixels can be taken at full resolution at 4:3 aspect ratio and 34 megapixels at 16:9 ratio.

Lens[edit]

The camera of the 808 has a very large and noticable hump

The optic is a 1-group lens, which is based on a shiftable fixed-focus lens: similar to the highly regarded prime lenses in most Zeiss Planar or Tessar optics, focus is achieved by varying the distance to the image sensor (unit focusing lens). This construction has the advantage that no movable focus group is needed. Considerable movable (focus-range) lens groups need a minimum of one additional adaptive lens element in both the moved group and the stationary group, increasing the number of elements by at least two. This increases unwanted reflections as well as overall tolerances and therefore decreases sharpness.

The lens consists of only 1 group with molded elements, which gives a highly stable, precise mechanical alignment. The lenses are partly made of plastic, which provides sufficient stability at this size and as a 1-group lens and has the significant advantage of making it possible to use extreme aspheric shaped lens elements.[14]

5 all-aspherical lens elements are used, making it possible to increase border-sharpness and lower distortion and astigmatism. The high–refractive index, low-dispersion glass additionally helps reduce chromatic aberrations. A neutral density filter with approximately ND8 (3 f-stops) is employed for shooting in high light levels where normally a smaller aperture would be set. Although the lens is named a Tessar, it has almost nothing in common with the 4 element in 3 group, non-aspherical original Tessar.

Due to the comparatively large image sensor format of 1/1.2-inch and the comparatively fast lens with f/2.4, the camera has a quite shallow depth of field of equivalent to approximately f/7.8 at 26 mm[16] on 35 mm full-frame.

Zoom[edit]

Zoom is digital but retains a high resolution due to the 41 Mpx sensor. The limit of the zoom is reached when the selected output resolution becomes the same as the input resolution. That means once the area of the sensor reaches 3072 x 1728, the zoom limit is reached. So the zoom always provides the true image resolution the user wants. The level of pixel oversampling is highest when zoom is not used. It gradually decreases until the maximum zoom is hit, where there is no oversampling. At this stage, PureView Pro optics and pixels start behaving in a more conventional way. But because only the centre of the optics is used, the best optical performance is achieved – including low distortion, no vignetting and highest levels of resolved detail. This also means that at full digital zoom, the noise reduction achieved by oversampling (pixel binning) is lost as no oversampling happens at full zoom.

Autofocus[edit]

The 808 PureView compared to its successor, Lumia 1020

PureView Pro features continuous auto focus in all shooting modes, close-up (Macro) focus, Face detection, Touch focus with easy manually selected focus point and Hyperfocal distance focus for defined depth of field, for extreme focus speed or when no reliable focus is possible due to darkness.

Video[edit]

The on-chip oversampling image processor of PureView Pro enables oversampling of all 38 megapixels even at the high video data rates of 1080p with 30 fps. Full HD 1080p gives 4x zoom; 720p HD video, 6x lossless zoom; and for nHD (640x360) video, 12x zoom. In addition, encoding is up to 25Mbps in 1080p H.264/MPEG-4 HD video format. The PureView Pro sensor integrates a special video processor that handles pixel scaling before sending the required number to the main image processor.

Audio[edit]

The 808 PureView employs Dolby Headphone software to transform stereo content to surround via a 3.5 mm A/V jack. It also includes Dolby Digital Plus software to provide 5.1 surround sound via HDMI or DLNA. The dual software elements from Dolby are embedded into the Nokia Belle feature pack 1 OS.

The 808 PureView is the first device to include the Nokia Rich Recording technology and has a frequency range between 25 Hz to around 19 kHz. The 808 PureView can capture sounds at the loudness level of 145 decibels without distortion. The two microphones, located at the top and the bottom enable ambient stereo recording. The audio encoding is done in AAC high profile, 256 kbit/s, 48000 Hz.

References[edit]

External links[edit]