Against its predecessor the K-30, the new 2013 model achieves very similar results. Indeed, they’re close enough to confirm that the firm is using the same sensor in both models.
Although the K-50 boasts a new image processor and a higher maximum sensitivity setting of ISO 51,200, there has been no real improvement in raw noise levels over the K-30 or earlier K-5 II, which share the same sensor.
Compared with similarly priced offerings from rival makers, the K-50 can easily out-do the $749 (body only) Canon EOS 700D/ Rebel T5i achieving quite a substantial 18 points more in the DxOMark Sensor Score over that model. At base ISO the sensor has a Color Depth equivalent to around +1.5 stops more than the Canon, and a wider dynamic range of +1.8 Evs. The difference in Low light scores are lower, something that Canon still does relatively well with despite the older sensor architecture but even then the Pentax has close to +2/3 stop advantage.
Against the $799 (body only) 24M-Pix Nikon D5200 the Pentax sensor is good but not quite up to the best. Not only is there a pixel count advantage but the Nikon is ahead in every category. The most significant is the +0.9 Ev extra in dynamic range, though in real world use the differences are less than the figures suggest.