Resolution, noise and sensitivity
I would far rather have a gritty, noisy image that is sharp and with plenty of detail than one that is mushy and noise-free. Pentax seems to be of a similar opinion, and although the images from its recent DSLRs, including the K-7, are quite noisy, they contain plenty of detail.
Unfortunately for Pentax, the Canon EOS 7D is a high-pixel-count camera that combines relatively low levels of noise with an impressive amount of detail. When captured with the noise-reduction systems in their default settings, high-sensitivity JPEG images from the Canon EOS 7D have significantly less noise than those from the K-7.
When raw files are captured to maximise the level of detail and allow the noise reduction to be carefully controlled, the two cameras are capable of capturing a similar level of detail at ISO 3200 (the K-7’s highest native sensitivity setting), but the Pentax images are have more chroma and luminance noise. Some images captured at the EOS 7D’s highest sensitivity expansion setting, ISO 12,800, look smoother and less noisy than those recorded by the Pentax K-7 at ISO 6400.
At lower sensitivity settings, the extra 3.4 million pixels offer the EOS 7D an advantage over the K-7, with the former resolving a little more detail that will be apparent in larger prints or when images are cropped and enlarged.
Image: These images show 72ppi sections of images of a resolution chart, still-life scene and a grey card, captured using matching 105mm macro lenses. 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. The section of the still-life image contains the emblem on a standard-sized matchbox. The full scene can be viewed at http://tinyurl.com/67sj96
