Hi, Human blood is red. Tending towards scarlet when it has oxygen attached, tending towards crimson when deoxygenated. It is this redness of the general tissue which gives red eye. The reason most cats (try photographing Siameses) give green eye is that they have an additional layer (the tapetum) on the back of the retina which reflects light. This enhances their low light sight by pushing photons which have not been "picked up" back through the receptor layer of the retina and doubling the chance of them being utilised. Told you it was boring. mike - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
