Behind the lens of a 41MP PureView Nokia Lumia 1020

Published by at

You've got to love a well done hardware promo, in this case Nokia's 1020 arty effort from the phone's launch. Yes, this video is now a few weeks old, but as a physicist I wanted to pick out several points, for others (like me) interested in the inner workings of Nokia's latest flagship camera phone. Although getting very close to representing what's going on inside, the video does take a number of liberties...!

Here's the video itself, you know what to do... Beneath the playback window are some salient screen grabs and comments, all up for discussion(!)

Impressively arty and... downright beautiful, though most aspects of the photographic process are stretched massively, to aid comprehension by the casual viewer. Here's the mechanical shutter opening and closing, to admit light - note that very, very few competing smartphones have mechanical shutters - most have the lens assembly and sensor always exposed to light and the shutter is 'electronic', effectively sampling the sensor output for a specified interval:

Screen grab

Nokia is also proud of its six element lens assembly, though the amateur in me does wonder why so many elements are needed. The clue is almost certainly in the need to keep the image free from 'barrel' distortion despite the wide optical angle and small dimensions involved. Effectively light has to be focussed accurately and yet spread evenly, and this requires up to six, somewhat irregularly contoured lens elements:

Screen grab

The other interesting thing shown off in the promo is the way OIS has been mechanised in the Lumia 1020, with a barrel shift mechanism balanced on a ring of ball bearings and driven by MEMS:

Screen grab

Of course, in the real camera, the light travels at.... well, the speed of light, and the OIS mechanism alters the angle of the optical 'barrel' at many hundreds of times per second (despite its bulk).

It's at this point that the promo gets more divorced from reality, with the lens shown as staying rock steady while the camera frame is wobbled (i.e. by the user's hand):

Screen grab

In fact, the sensor is also part of the camera frame, being mounted into the back of it, so having light coming in a steady stream towards a wobbling sensor is no good at all. So, not shown in the video because it would complicate things for the casual viewer, but in reality the lens assembly is tilted in the opposite direction to movements from the camera frame/phone.

I.e. the phone is jolted upwards and the optical assembly is tilted downwards (as seen from the front), in order to angle the focussed light up by the just right amount to match the sensor/frame movement. So the thing you're focussing on has its light still focussed at the same spot on the sensor.

Also shown in the video, though moving away from the camera itself, is the Lumia 1020's display. Unlike older Nokias with AMOLED displays, such as the 41MP PureView predecessor, the Nokia 808, which had a traditional RGB display (Red, Green, Blue sub-pixels in equal size, one of each per display pixel), the Lumia 1020 (and the 925 and 928) has a 'pentile' display, where pixels alternate red and blue output, with smaller green sub-pixels interspersed:

Screen grab

Pentile AMOLED displays are reckoned to have (potentially) longer life, higher brightness and lower cost, but the obvious downside is that there's a slight 'fuzziness' to be seen in small displayed details, especially if you have good eyesight. These things are an obvious tradeoff for manufacturers, though it's perhaps significant that Samsung does mostly the same as Nokia with most of its higher resolution AMOLED displays, though the exact sub-pixel layout does vary slightly.

A fascinating big-budget promo from Nokia though - kudos to the animation team behind it. Just don't take everything you see as literally true in terms of physics!

Source / Credit: YouTube