Photography is a photophysical process, where the photon interact with the matter and then carry relevant details along with emotion and time to the viewer. Photography freezes time, and let you revisit your past.It's a wonderful science that has come into origin ever since man has understood the working of human eyes.The working principle of camera and human eye are same. But the technical capabilities that human eyes poses that is an outcome of million year of evolution is far greater than camera that has its origin for just close to a century.
Photography is an outcome of light from source being reflected/diffused or scattered from object that reaches the detector/films. Where else Vision is a result of interaction between human eye and adaptive image recognition undertaken by brain, which makes it the most complicated image sensing device that can be ever thought of.
Human eye as seen from the figure has a lens which undergo contraction and expansion through iris, thereby changing its focal length. The iris diaphragm opens wider for faint light and closes down in case of bright light. The lens is immersed in between 2 fluids referred to as Aqueous humor and Vitreous humor having refractive index of 1.336 and . The size of human pupil varies between 2mm to 7mm. The lens from the image on the retina which contains photoreceptors Rods & Cones which convert the photon energy into electrical signal that is interpreted by the brain as image. Rods are responsible for intensity detection and Cones are color sensitive. There are 3 types of cones sensitive to blue, green and red part of the visible spectrum. Cones are responsible for vision during day, and rods during night time. We have around 120-130 million of cones and around 10 million rod on our retina. Considering a large field of view human eye has a resolution of close to 500 Megapixel. In a single view Eye can detect contrast change of 10,000 ie it can function normally under bright sunlight as well as dim faint star light. Where else the eyes focal length is around 22mm. These are the technical details associated with human eyes which surpass every camera specification we can ever think of.
But there are few specification that camera poses over which has great advantage over human eye. The photoreceptors in eyes has a temporal resolution of around 1/20 sec, for any motion greater than this time scale eyes see it as continues vision. Where else in camera we can play with shutter speed for time upto to 1/8000 sec under sufficient illumination and captures images which can never be imagined. Something like bullet through soft material. And also we can have long exposure on camera to have drastic effect which human eyes is incapable of achieving. Since human eye combines images formed every moment, its not possible to have certain effect like long exposure scene through human vision.
Nevertheless human eye if properly understood it can result in awesome shot being taken. Simple adaptive optics associated with eye and human brain forms the best imaging device.
