Monday, February 27, 2012

Nokia 808 Pure View : Some more camera details !

Posted on 20:21 by SlipKoRnSaad

What's the Nokia 808 Pure View camera is all about?

Folks over did give a nice overlook at it based on Nokia documentations about that, it's a :

• Carl Zeiss optics of focal length: 8.02mm
• 35mm equivalent focal length: 26mm, 16:9 | 28mm, 4:3
• F-number: f/2.4
• Focus range: 15cm – Infinity (throughout the zoom range)
• Construction:
· 5 elements, 1 group.All lens surfaces are aspherical
· One high-index, low-dispersion glass mould lens
· Mechanical shutter with neutral density filter
• Optical format: 1/1.2”
• Total number of pixels: 7728 x 5368
• Pixel Size: 1.4 microns

The sensor actually has 41 megapixels, meaning it is filled with 41 milion pixels with 7728 x 5368 pixels in horizontal and vertical respectively. It has a 4:3/16:9 hybrid sensor that manages to capture equivalent field of views on both the aspect ratios, just like the N9/Lumia 800. So, depending on the aspect ratio you choose, it will use 7728 x 4354 pixels for 16:9 images/videos, or 7152 x 5368 pixels for 4:3 images/videos. This image from the white paper explains it so clearly :

So, the sensor will provide a maximum 38 megapixel image on 4:3 aspect ratio at the resolution- 7152 x 5368 and a 34 megapixel image on 16:9 aspect ratio at the resolution- 7728 x 4354.

 “Pure View” is all about insane amounts of detail on a single photo. How do they do it? Let me explain as simple as possible.

The camera has two sensor modes: “Pure View” and “Full resolution”. The “full resolution” mode is what I explained above, there are two options for 4:3 and 16:9 with 38 and 34 MP respectively, while in the “Pure view” mode, these are the options-

There, you have three options, 5 megapixels being the default, and 8/3 megapixels being the only other two options. So, why does it have very low MP counts, you ask? Well, for enabling some insane amount of detail in a single pic, even after 100% zoom, they have used something called “Pixel oversampling”. Take for example, 5 megapixels, the resolution would be 3072 x 1728. Each pixel of that resolution is actually a “super” pixel, which has image data from 7 neighboring pixels. So, one pixel has image data of 8 pixels, making the ratio of Pixel Oversampling(O’sam.) for a single 5 megapixel image to be 8:1. Similarly, for an eight mpix image, the O’sam. ratio would be 5:1, meaning one super pixel contains image data from 5 pixels. Thus, processing several pixels at once, makes the image much more detailed, like insanely detailed, with virtually no grainy image noise, that you usually get from any other camera phone, even the N8 has fine grain noise on every picture.Not only that, thanks to the fricking huge 41 mpix sensor, we can use some lossless zoom on all the pure view modes.

For example, the 5 megapixel mode will have maximum O’sam. at minimum zoom, and when the zoom increases in steps, the O’sam. decreases until the zoom reaches the exact resolution at the center of the sensor at pure 3072×1728. At the center of the sensor at 5 mpix resolution, the O’sa. would be zero. So, until the full sensor crop is utilized, the image quality remains largely the same, and hence, lossless zoom without having to use optical zoom or interpolation techniques. Since the data processed during all this manipulation is huge, the CPU+GPU cannot handle everything, so, there is a dedicated scaling chip that takes care of the O’sam. range when the zoom is happening.

This graph might help you with what I told about O’sam. ratios and Zoom range-

 So, basically you can achieve nearly 4x lossless zoom at 3 Mpix setting and as you can see, at 1:1 O’sam. the zoom factor is highest. Ok, it may seem a bit intimidating if I explain more, let’s get to the next big thing in 808 pure view, the Video mode!

The 808 can take full HD videos at 1920×1080 resolution at 30 FPS, and I love the fact that they have used the same concept of Oversampling in video too, hence creating some stunning detail, and upto 4x lossless zoom. Words can’t really describe how awesome the low light performance, just watch this video in 1080p-

There are other frame rate options for 1080p like 24 and 15, while there are video modes for 720p which offers 6x lossless zoom and nHD(640×360) which offers 12x lossless zoom! Just like the crop video mode on the Canon EOS 550D, but I hope it did the 1080p crop like the 808 

And coming to other intricate details of the camera unit, the aperture at f2.4 is fixed, Nokia says it is an advantage when compared with DSLRs with optical zooms that reduce the maximum aperture at full zoom, like on the 18-55 kit lens, the max. aperture is f5.6 at 55mm. But since the 808 has no moving elements, there is no change in aperture and you get lossless zoom like optical zoom at same aperture throughout. Not really sure why Nokia has mentioned it in the whitepaper.And as a consequence of this, the flash range and shutter speed/ISO don’t get affected at  various zoom ranges. The maximum ISO for the 808 is 1600. And for brighter situations, the handy ND filter is present, just like the N8 

And the focal length at 8.04 mm coupled with a f/2.4 aperture gives you a shallower depth of field but a narrower view than the usual cameraphones which have 4 mm focal lengths. For comparisons sake, let’s take the 18mm focal length in a kit lens, it offers a very wide angle of view, while 50 mm offers a narrower view but a shallower depth of field. Likewise, the 8.04 mm focal length will provide a shallower DoF, which will in turn provide a nice Bokeh. Really looking forward to that!

Coming to pixel level details, the 808 has a 2.5 times larger sensor than the N8, with it’s size at 1/1.2″ while the N8 was 1/1.83″. Moreover, each pixel on the N8 was of 1.75 microns in length, while the 808′s pixels are even larger. Not really sure what’s the size though. And coming to audio-

In combination with the world’s first implementation of Nokia Rich Recording technology, Nokia 808 PureView records best in class stereo audio with every detail. Whilst most high end smartphones can only record without distortion to around 110db, the Nokia 808 can comfortably continue to around 140-145 db, which is 4 times louder than conventional mics can record. Apart from that Nokia Rich Recording can also record very low frequencies also without any distortion. The combination of all of these elements means the  Nokia 808 records audio with almost CD like quality. It has to be heard to be believed. In terms of both visual and audible performance, the Nokia 808 simply has no equal.

Are those words sufficient for convincing you how great it is? Concerts and noisy places will be handled much better than the N8, which was already too awesome!

Also, apart from these details about the sensor, there is a very much improved auto focus in all the video modes like touch to focus, conventional focus, and even the UI is vastly improved, with something really cool called “slide zoom” . You just slide your fingers over the screen and it lets you zoom selectively, the frame.

What else?

specifications over

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