Skiddaw by moonlight

We climbed up to the Watches above Bassenthwaite by moonlight and I took this lovely picture of Skiddaw. Well, I could see Skiddaw clearly but it hasn't appeared in the photograph. You can see the tip of my ice axe reflecting the moonlight. The CCD pixels in my camera are not as sensitive to light as the rod cells in my eyes. Rod cells are found round the edges of your eyes and cannot detect colour. The pigment in them is depleted in bright light but regenerates when it goes dark - hence the dark adapted eye. A rod cell can detect a single photon of light which makes it up to 100 times more sensitive than the cone cells in the middle of your retina. Also, more than one rod cell is connected to the same nerve fibre so it can amplify the signal. This does reduce the resolution of the image. They also record photons for a longer time - it takes about 0.2 seconds to build up an image. This makes the picture seem brighter but makes it harder to see very sudden movements. Being around the edge of your retina, it explains why the path seems bright until you look down at it directly.