Noise, sensitivity and resolution
The OM-D E-M5 has an ISO range of 8EV at ISO 200-25,600, which is an extra stop over other Olympus models and class-leading in the four thirds format.
With the highest pixel count of any Olympus digital camera, it comes as no surprise that the E-M5 resolves the highest level of detail. The 16.1-million-pixel sensor is able to reach the 26 marker at ISO 200 in raw and JPEG images using the 12-50mm f/3.5-6.3 lens, and the 28 marker in raw and JPEG files with the 45mm f/1.8. This performance matches the Panasonic Lumix DMC-G3 and other cameras with the same number of pixels, as the best-performing four thirds unit.
With more pixels to be fitted on the same-sized four thirds sensor, each pixel on the E-M5 sensor must therefore be smaller. If previous cameras are anything to go by, the pixel pitch of 16-million-pixel four thirds models is approximately 3.7 microns compared to 4.2 microns in 12-million-pixel models like the Pen E-P3.
We would expect each pixel to collect less light, which would in turn affect the saturation, dynamic range and levels of noise in low light. However, as we have seen when Panasonic jumped from 12 to 16 million pixels, and now in the E-M5, improvements to the sensor and image processing, among other things, make it possible to maintain the performance of the camera.
The E-M5 uses Olympus’s TruePic VI processor, as does the current generation of Pen models. For images taken in low light, our resolution charts indicate that despite the increase in pixels, and their resulting smaller size, the E-M5 is as capable as other Olympus models in low light in terms of saturation, dynamic range and levels of noise. However, it is not any better. Luminance noise affects resolved detail, and by ISO 12,800 the camera reaches the 20 marker on our resolution charts. Detail and saturation at the maximum ISO 25,600 rating are decreased, which means this setting should only be used as a last resort.
Image: At ISO 1600 detail is still pretty crisp, although there is luminance noise in the form of fine grain
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using two Olympus lenses set to their sharpest apertures. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
