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
The Torment of a Flower The Torment of a Flower The Torment of a Flower (), also known as Rainy Night Flower, is a Taiwanese Hokkien song composed by Teng Yu-hsien (; 1906 - 1944) and written by Chou Tien-wang (). A Taiwanese writer Liau Han-sin (廖漢臣) wrote the lyrics of a children's song ""Spring"" (春天) and gave it to Teng Yu-hsien to ask him to compose for it, it's the earliest version of "The Torment of a Flower." Although Teng is a Hakkan, he usually composed with Taiwanese Hokkien but not Hakkan. It is worth noting that some scholars have questioned this story about