Olympus OM-D E-M5 Mark II sensor review: New features, but same sensor resolutionBy Paul Carroll - Tuesday April 07 2015 Sensor Review
Comparison 2: Olympus E-M5 Mark II vs Sony a6000 vs Sony A7R
Unsurprisingly, against the best-performing APS-C and full-frame sensors in the Sony a6000 and a7R hybrid cameras, respectively, the lower resolution and physically smaller Olympus four-thirds sensor is a little off the pace.
The increase in physical sensor size from the Olympus’s 13x17.3mm four-thirds sensor to the Sony a6000’s 15.6x23.5mm APS-C sensor equates to around 2/3rds of a stop better performance from the bigger sensor across the board. Step up in size again to the Sony A7R’s 24x35.9mm’s full-frame offering, and the difference is roughly the same again, putting Sony’s A7R almost 2 stops ahead of the E-M5 Mark II in all categories.
For Dynamic Range, however, the advantage of Sony’s larger sensors is only that wide at base ISO 100, with the gap narrowing somewhat as sensitivity increases. In fact, between ISO 200 to ISO 3200, Dynamic Range performance between the E-M5 Mark II and Sony a6000 is much closer, and while the A7R stays out in front, the differences between the sensors at higher ISOs isn’t quite as wide as the headline scores initially indicate.
It’s not quite the same pattern for Color Sensitivity, however, where the Sony a6000 and A7R offer fairly consistent improvements in color graduations at all ISO sensitivities. The A7R is just under 2 stops better than the E-M5 Mark II for color throughout the ISO range, so although good color rendition of over 20 bits is possible on the E-M5 Mark II up to ISO 400, the Sony A7R delivers the same color up to ISO 1600. The same is true for ISO signal-to-noise results, too, where the larger full-frame A7R sensor offers good results of over 32 dB up to ISO 1600, compared to the E-M5, which drops below 32 dB at around ISO 400.