Noise, resolution and sensitivity
Nikon has made significant changes from the P6000, opting for a lower pixel count and a higher maximum sensitivity setting in the Coolpix P7000. The new model has 10.1 million pixels rather than the 13.5 million pixels of its predecessor, and a sensitivity range of ISO 100-3200 rather than ISO 64-1600.
This follows the trend of offering fewer pixels in favour of a reduction in levels of noise. With 10.1 million pixels and good resolution, the P7000 can produce clean A3 prints, whereas a camera with a higher pixel count but poor noise control cannot. This explains the emphasis on better noise control at the expense of pixels.
Image: I shot this music gig at ISO 1600. Close inspection shows the P7000 copes with noise pretty well in this type of setting
At ISO 100, JPEG images reach around 20 on our charts, which is not quite as impressive as the Canon PowerShot G11, but good nonetheless. This resolution is consistent to ISO 400 and only has a minor drop at ISO 800 and ISO 1600. After this, the resolution drops significantly. Noise is evident to the discerning at ISO 400 and is significant at ISO 1600 and higher.
Left: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, 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
Right:This graph shows the brightness values recorded by the test camera when it is used to photograph a stepped graduation wedge. The wedge has transmission values in 1⁄2EV steps ranging from 0 to 12EV. The camera’s exposure is set so the 12EV section in the wedge has a brightness value of 255. Software analysis of the image then determines the recorded brightness values of all the other steps and calculates the camera’s dynamic range.
