Technically Speaking
The Nokia Lumia 1020 uses a 1/1.5-inch 41-megapixel PureView sensor which effectively allows you to capture 34-megapixel in 16:9 ratio or 38-megaxpiel in 4:3 ratio. The image quality is delivered to the sensor with 6 Carl Zeiss lens elements. For every shot taken on a Nokia Pro Cam app, a 5-megapixel image will be saved simultaneously, with each pixel oversampled with surrounding pixels data. The result is fewer colour noise artifacts.
Lumia 1020 has fewer colour artefacts thanks to oversampling.
The Lumia 1020 also has a built-in optical image stabilizer that moves the entire lens assembly, so that low light images remain frozen without handshake, and you can still get stable images even with slow shutter. Video footages appear less jagged.
With the large sensor, Nokia has implemented "high resolution zoom", which means as you zoom-in your still or video images, the phone continues to make use of every pixel for the footage instead of a digital zoom. Some manufacturers term it as "smart zoom" or "intelligent zoom". Another less-mentioned technical advantage of high resolution zoom as opposed to optical zoom is that high-res zoom will not result in a drop in aperture, while compact optical zoom lens will result in less light and smaller aperture as you zoom-in, reducing shutter speed.
Because the Nokia Lumia 1020 has a high-pixel count, it can deliver high resolution zoom: 3x for 5MP image, 6x for 1280x720 image.
Besides the image quality, shooting video delivers better audio quality as the microphones can handle high sound pressure levels to capture better dynamic range.
