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2. Inside-story

GLOBAL – Damian Dinning is Nokia’s resident expert and enthusiast on all things camera flavoured, so we were keen to capture his insight on our Design by Community project and the camera choices we’ve laid out in this week’s widget.

We managed to corner him for a chat and quickly discovered that imagining an 18-megapixel device with a 10x optical zoom is indeed the stuff of fantasy with today’s technology and manufacturing techniques – but certainly a dream worth contemplating and discussing. Read on to find out why this feature set would be implausible today and what the implications might be.

Monster megapixels
We asked Damian what would need to happen for a mobile device to be able to host an 18 megapixel camera with a 10x optical zoom. First he addresses megapixels, camera performance, image quality, cost implications and the size issues that arise when pursuing the ultimate dream optics.

“First you need to establish how good the low light performance would need to be. That would help determine how big the sensor capturing 18 million megapixels needs to be. Then you need to work out how close you want to be to your subject when taking photos to establish the depth of the optics. If you want a macro that lets you take shots from less than 10cm away there’s a significant amount of movement of optics that’s required within the module that affects the size. Then throw in variable aperture settings like in the N86 and this also increases the size. A mechanical shutter also affects the depth of the camera module. If you want a wide angle of view that again adds to the size. That’s before you add a lens cover, and ask yourself whether it should have optical grade glass or a mechanical sliding cover. Manufacturing ability also needs consideration. The more optics you have, the more pieces of glass, the more the cost and size will go up. The manufacturing tolerance is impacted as lens design becomes more complicated and it again becomes a cost issue. Tightening up the precision of optics requires increase in materials and size.”

Outrageous optical zoom
So onto the nitty gritty of what the actual limitations are with today’s technology in putting an 18 megapixel camera in a device with a 10x optical zoom. Damian started scribbling on the back of a napkin to come up with these insightful approximations.

“If we take the N86 as the typical size for an 8-megapixel module, this currently measures in at 12.5 x 12.5mm and 9mm in height. So if the sensor were to be over double the size [18MP] the module would increase by around 50 per cent on each side. So roughly 18mm x 18mm and 14mm deep. However, then you need to consider the driving mechanism for the autofocus. It wouldn’t necessarily double the size of the module again, but the driving mechanism might need beefing up so that again would increase the footprint. If you don’t increase the height of the module issues arise with image quality – the problem is that the corners of an image end up looking darker. Then comes the zoom. In a basic zoom two lenses are moving. You then need additional lenses to control image distortion, ensure the image is sharp, and the contrast is controlled. The only way to do a 10x optical zoom with a high end sensor would be to do it through some form of folded optics design. As a rough guide a 3x optical zoom with folded prism optics would be three times the size of a conventional non zoom model as you’d find in the N86. So you’d need to more than double that should it have an 18 megapixel sensor. And with a 10x zoom I’d hazard a guess that it’d need to be at least three times bigger again.”

By our estimations that would bring it in at around half the size of the entire handset! So certainly a prohibitive option with today’s technology. Still, let’s keep dreaming.

What do you think? Is the concept of an 18 megapixel camera overkill, and do you really dream of a 10x optical zoom in a mobile device? As always share your thoughts in the comments section below.