Noise, resolution and sensitivity
Images display pin sharpness using the new 55mm lens, although DSLR users should be aware that depth of field can be very shallow
The detail that can be obtained from a 40-million-pixel sensor of this size is truly breathtaking. When compared directly with similar shots taken on Nikon’s 24-million-pixel D3X, the difference in detail at 100% magnification is starkly obvious – from a full-length portrait the pores in the skin on the model’s face were still crisp on the 645D, while the D3X was running out of pixels.
On our resolution chart, both JPEGs and raw files reached around 38, and with a little extra sharpening and noise reduction, raw could arguably have gone even further. The beauty of the 645D raw files is that, with a choice of both PEF and the standard Adobe DNG file, they are already supported (at least in DNG) by most existing raw software.
Image: Even at the camera’s highest setting of ISO 1600, noise is still well controlled and detail remains well defined
The standard sensitivity range of the 645D is actually ISO 200-1000, with 100 and 1600 considered ‘boost’ settings. There are subtle signs of noise in shadow areas from ISO 400 upwards, but this remains monochromatic and little more than a slight texture right up to ISO 1000. The ISO 1600 setting does start to show some colour noise, but this is still kept to a minimum and can be largely removed in processing.
Resolution charts: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using a Pentax 55mm f/2.8 AL SDM lens. 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.
