Noise, Resolution and Sensitivity
Despite the backlit sensor being designed to reduce noise, I found that luminance noise is present in images captured at all ISO sensitivities, including the minimum ISO 100. However, it doesn’t become an issue until around ISO 800.
The default noise-reduction setting helps to reduce the luminance noise, but images do start to show the characteristic smudged appearance as the sensitivity increases. Of course, DNG raw files show the true extent of the luminance noise, but also more detail.
Chroma noise also increases with the ISO sensitivity and by the time the maximum ISO 3200 sensitivity is reached, JPEG images are almost devoid of any fine detail and look like impressionist paintings.
With no noise reduction, raw files are obliterated by both luminance and colour noise, and it is difficult to make out any details. Even with the colour noise reduction in Adobe Camera Raw 5 set to 100, purple and green patches are still visible. Reducing the luminance noise is even more difficult and it is almost a fruitless task, with results no better than the in-camera JPEGs.
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using the lens set to around 105mm equivalent. 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.
