Resolution, noise and sensitivity
As our resolution test images show, the Pentax K-7 is capable of resolving an impressively high level of detail, especially in raw files at the lower sensitivity settings. Simultaneously captured JPEG files are also good.
Kit lenses are rarely perfect, but I was both surprised and disappointed to find that our sample of the new weather-resistant smc Pentax-DA 18-55mm f/3.5-5.6 AL WR lens resulted in images that are noticeably softer than the smc Pentax-DA 18-55mm f/3.5-5.6 AL II optic supplied with the K20D kit. The corners are especially poor and suffer from astigmatism.
Most of my JPEG files benefit from an application of Unsharp Mask, but it cannot resolve the problem of blurring of detail towards the edges of the image. Several of my images have the main subject towards the edge of the frame and they are disappointingly soft.
Noise makes an early appearance in images from the K-7. High-sensitivity images have a lot of chroma noise, but the raw files are sharp. As usual, JPEG files are softer and a little smudgy when the high-sensitivity noise-reduction system is in its default medium setting.
I prefer the sharper, grittier results when no in-camera noise reduction is applied. The noise is fairly evenly distributed and banding isn’t a major issue. I particularly like the images produced with the camera set to its highest expanded sensitivity setting of ISO 6400 when shooting monochrome images.
These images above show sections of images of a resolution chart, still-life scene and a grey card. 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.