Low Light - Output Modes Compared:

The simple fact that the 808 offers user-selectable ISO sensitivity settings up to ISO 1600 makes it considerably more versatile than the average cameraphone when the light gets low. On this page, I want to see not only whether the output is any good, but also, whether the 808's PureView modes offer significantly better image quality than the maximum resolution output. 

For this test I put the 808 on a tripod and shot the same scene at ISO 1600 at all four of its output resolutions. Light was provided by a single low-intensity tungsten bulb, and exposure was 1/25 sec at F2.4. I used a 2 second self-timer to make sure that everything stayed sharp. 

 
 3MP (100% Crop)  5MP (100% Crop)
 8MP (100% Crop)  38MP (100% Crop)
It's hard, looking at 100% crops, to really say which of the 808's three PureView modes gives the best image quality, because of the disparity between the magnification at 100%. Scene detail that is smallest (in the 3MP shot in this case) always looks a little better defined than the same detail, reproduced larger. By 38MP, the disparity in magnification is so great that direct comparison is difficult, although it is obvious that at a pixel level, the 808's output is much grainier, and less sharp than it is in the lower-resolution PureView modes. 

3MP PureView versus 38MP>3MP 

To get a better idea of how these modes compare, I've downsampled the 38MP file to the same dimensions as the 3MP file, using Photoshop's Bicubic Sharper downsampling algorithm. 
3MP (100% Crop) 38MP downsampled to 3MP (100% Crop)
 3MP (100% Crop) 38MP downsampled to 3MP (100% Crop)
You might need to dim the lights in your room to see the difference, but there is a difference. The downsampled 38MP file is sharper than the native 3MP capture, but grittier, and the blue noise at lower right is blotchier, too.
 
Interestingly, in all of the images, noise is noticeably more intense in the right half of the images than it is elsewhere in the scene. This isn't due to the position of the light in our setup - our tungsten lamp was positioned on the left - but probably due to amp glow, maybe caused by heat, originating from a component positioned behind or adjacent to the 808's sensor inside the tightly-packed body of the phone. In our 'real world' shooting at the 808's highest ISO settings, this issue is unnoticeable, although banding can be a problem in very poor light. 

So is the difference between the various output modes big enough  to justify shooting at 3MP when 5, 8 and 38MP are available? On the basis of these tests I'd have to say that in my opinion no, it isn't. The most significant benefit of shooting at 3MP and 5MP has already been highlighted - namely, a greater effective 'zoom' compared to 8MP, which in turn offers greater versatility than full-resolution mode, where you can't 'zoom' at all. The 808's 5MP PureView mode is a good compromise between resolution, filesize and versatility when it comes to framing, which is probably why Nokia made it the default. As I mentioned earlier in this article, I have also noticed that clipped highlights are slightly less of a problem in the 808's PureView modes compared to full resolution, but clipping (to some degree) remains an issue in all modes. 

Studio Comparisons

We wouldn't normally put a cameraphone through our studio comparison test, but given its impressive specifications we wanted to see how well the 808 PureView compares to the many different cameras in our database. We shot our studio scene twice - once at the 808's full resolution of 38MP and again at 8MP, in PureView mode. We chose to showcase 8MP because it is the highest resolution PureView mode, and as such, more comparable when it comes to examining images alongside those from dedicated compact and system cameras. Click the thumbnail below to view the studio comparison (output modes are selected via the 'ISO' dropdown).

Studio Comparison

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F). The 808 PureView was positioned on a tripod, and was set to flurescent WB. Exposure was adjusted using exposure compensation and the built-in ND filter to achieve near-parity of exposure between ISO sensitivity settings.

Click here to see how the 808 PureView performs in our standard studio comparison

Click the thumbnail image above to see how the 808 PureView performs in our studio comparison scene. (opens in new window)
It's hard not to be impressed by the 808's performance here, especially at low ISO sensitivity settings. At its maximum resolution of 38MP the 808 is capable of capturing a ton of detail, and pixel-level image quality is up there with some of the best cameras around. In its 8MP PureView mode pixel-level image quality is extremely high at low ISO settings, and even up at its highest ISOs, the 808 gives a lot of 'proper' cameras a run for their money.