Sony has been persistent in using the same 20.7MP sensor for its flagship camera setup since the Xperia Z1. That makes for four generations of regular-sized Z-series members and two Compacts, so it's fair to say that the imager was due for a replacement. That's precisely what Sony did and it's now introduced a brand new custom sensor, exclusive to the company's own device portfolio. Sources from Japan call it IMX300, but we couldn't verify that. The chip debuts on the just announced Xperia Z5 lineup and is paired with an f/2.0 24mm-equivalent wide-angle lens. The smartphone camera is being advertised as 23MP, and that's what's engraved on the backs of all three models, but that number only tells part of the story. While we were shooting our camera samples with the pre-production models we have at the office, we noticed a discrepancy between the dimensions of 16:9 and 4:3 shots. That led us to dig in a little and we discovered that the camera utilizes what's become known as a multi-aspect sensor. Samples shot in 4:3 and 16:9 aspect ratios Photos shot in 4:3 aspect come out at the headline 23MP resolution, or 5,520 x 4,140 pixels (22.85MP, but who's counting). Meanwhile, the 16:9 aspect yields images, measuring 5,984 x 3,366 pixels (20.14MP). What you'll notice, is that the 16:9 shots are wider than the 4:3 ones, hence they're not cropped from 4:3, but instead use a different part of a larger sensor. Basically, the effective area of the imager is at least (or exactly, we have no way of knowing) 5,984 x 4,140 pixels, totaling 24.77MP. The concept allows for optimum utilization of the image circle, projected by the lens, but also means you get comparable resolution in both ratios. For example, if you were to extract a 16:9 aspect photo from a supposed 5,520 x 4,140 native 4:3 sensor, you'd be left with 5,520 x 3,105 pixels, or only 17.14MP. Additionally, your field of view (measured diagonally) would be narrower. With the multi-aspect sensor you get 3MP more and the same diagonal field of view, though obviously wider horizontal coverage. All that comes at the expense of wasting the extreme corners of the sensor, which we're inclined to agree is a minor trade-off. Sony, naturally, went the obvious route and branded the camera as 23MP, choosing go keep the nitty-gritties to itself. If it were to announce a 25MP camera, but users could only select a 23MP maximum resolution, we reckon marketing will have a lot to explain. More or less, the...
Source: http://www.gsmarena.com/tech_explained_sonys_new_zseries_uses_a_brand_new_custom_camera_sensor-news-13806.php
