Human eye The upper end of the range is given in terms of normal visual performance as 10 cd/m (100,000,000 or one hundred million candelas per square meter). The eye includes a lens similar to lenses found in optical instruments such as cameras and the same physics principles can be applied. The pupil of the human eye is its aperture; the iris is the diaphragm that serves as the aperture stop. Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it
A Poke in the Eye (With a Sharp Stick) A Poke in the Eye (With a Sharp Stick) A Poke in the Eye (With a Sharp Stick) is the title of the first show in what later became the iconic "Secret Policeman's Ball" series of benefit shows for human rights organization Amnesty International, although it pre-dated by three years the first show to bear that name.. The film of the show was titled "Pleasure At Her Majesty's" which is sometimes mistakenly thought to be the title of the actual benefit show. The landmark 1976 show starring the Monty Python, Beyond The Fringe and The Goodies teams and other top