[Xperia Z General] silmarils:
Having used XZ's camera for some hundred pictures in various conditions, I have to comment on the very smart automatic mode. It does produce excellent results in identifying conditions and exposure and colour rendition are trully very good. However, photograhic quality is just not there. Detail suffers a lot from either noise or too much post processing. In some cases when viewing at 1:1 zoom, it reminds me the results of applying some of photoshop's artistic filters in a subtle yet identifiable way.

Sony must have had a reason to incorporate such heavy post processing. The Exmor RS module was originally designed to handle RGBW coding (white plus the traditional RGB). Apparently somewhere along the way, Sony changed their minds as they could not make it work to their "image quality standards" and reverted back to traditional RGB (1), (2). One can only make assumptions, but perhaps the rather heavy noise processing of the image and compression may have its roots to decisions taken to correct other issues, ie. degraded light performance and consequent noise through higher ISOs.

It would be interesting to see how the sensor performs in other phones. One example is the Oppo Find 5. Unfortunately the results are pretty much the same, ie. plenty of noise which brings down detail. (3), (4) Which can only mean that the root of the problem is either any firmware handling the signal of the actual image sensor or that the design itself is flawed.

It is rumoured that the same sensor will also be used in the new SGS4 (we will know soon enough) and the revised iPhone 5S. So let's wait and see what they can make of it. It would be disappointing to see two highly anticipated phones featuring worse cameras than the models they are replacing.

In photographic terms, the way to get better pictures is larger aperture and image stabilization. Letting more light in is the secret and there are two ways of doing it: larger aperture or longer exposure times. The latter results in shaky pictures which is counteracted to some extent though image stabilization. The former usually requires a longer camera+lens module. (in DSLRs larger aperture also means small DOF but this is not an issue for phone cameras where the sensor is so small). That's why incorporating a F/2.0 or F/2.2 aperture usually means thicker phone or a lump at the back. Sony also makes a F/2.2 module which is 5.5mm thick vs 4.2mm for the F/2.4 which was selected for the XZ, probably to keep its thickness to an impressive 7.9mm. (5) The larger aperture could also an excuse for the thickness of the Nokia Lumia 920 which its F/2.0 aperture lens. (6) However, Lumia 920 does pull it off and the result of a good sensor, the F/2.0 aperture and optical image stabilization is great photographic quality. Another approach is having less pixels, something HTC implemented in the One, which again features a F/2.0 aperture @ 9.3mm thickness. However this also has obvious disadvantages in losing detail and the ability to crop a photograph.

Higher pixel count, 13MP vs 8MP, also means that to get the same exposure with the same speed, aperture and ISO rating you need MORE light. (7) Thus, when 8MP is pretty good resolution for every day photography, increasing the pixel count just for the sake of it is the wrong way to go. I do not need to use my Canon 550D at more than 8MP, even when on holidays, even though it supports 18MP resolution.

What has the future in store for us? Well, Sony has made a large investment in the new assembly line and tools to produce the Exmor RS series and they want to see it through. So, I would expect to see revised editions of the module with significant improvements.

Many thanks for reading.

Sources

(1) engadget.com/2012/09/21/sony-exmor-rs-stacked-phone-camera-sensors-detuned-over-quality/

(2) droiddog.com/android-blog/2012/09/sonys-exmor-rs-sensors-downgraded-due-to-quality-concerns/

(3) gizmochina.com/2012/12/15/oppo-find-5-using-sony-cmos-exmor-rs-sensor-camera-component/

(4) gsmarena.com/oppo_find_5-review-880p8.php

(5) imaging-resource.com/news/2012/08/20/sony-exmor-rs-sensors-to-allow-slimmer-better-camera-phones

(6) nokia.com/global/products/phone/lumia920/specifications/[/url]

(7) wpcentral.com/thoughts-and-impressions-nokia-lumia-920s-pureview-camera