Human Eye and Camera

Topics: Eye, Retina, Photographic lens Pages: 8 (2356 words) Published: January 7, 2011
The human eye and a camera lens have a few things in common most notably that they both use a converging lens to receive and project images. But human eyes and camera lenses have many things that set them apart from each other.

“Retina Provides Color

• the image an eye perceives is projected from the cornea to the retina, which absorbs the image and projects it to the brain. A camera projects an image on to film where it is captured and saved as a black and white image. The retina contains millions of cones that provide the image with color.

Stereoscopic View

• the biggest difference between eyes and a camera lens is that two eyes give us stereoscopic vision. This allows our eyes to project a more detailed image to the brain than a single camera lens and provide depth of field, something a single camera lens can't do.

Light Sensitivity

• a camera lens projects an image onto film that has chemicals with a uniform sensitivity to light. The eye project images on to the retina that has rods with varying capacities to absorb light.

Light Adjustment

• the human eye controls how much light it receives by reducing and enlarging the size of the pupil. A camera lens has to be adjusted to receive the proper amount of light.

Cameras Have no Blind Spot

• the human eye has a "blind spot" located where the optic nerve leaves your eye and connects to the brain. At that connection point, the eye can't see anything. A camera lens doesn't have a connecting point like this and has no blind spot. Table: Similarities & the Difference between Camera and Human Eye Function Camera Human Eye


• Opening for light to enter- Aperture
• control the amount of light entering camera/eye- Diaphragm control size of aperture • refract light-glass biconvex lens
• object of light action to form image-photosensitive chemicals on film • absorb excessive light to prevent multiple images formation-dark internal surface Human Eye
• pupil
• iris muscles control size of pupil
• mainly cornea ;
lens, aqueous & vitreous humor
• photoreceptors(rods & cones) in retina
• pigmented, dark choroid
• focusing mechanism-change distance between lens & film for Camera Change focal length of lens using ciliary muscles for Human Eye

1-the human eyes uses living cells while the camera is artificial, 2-the eye focus the image using the retina while the camera changes the position of the lenses, 3-the amount of light enters the eye is control by the iris while in camera it is by the diaphragm

The human eye vs. a camera: how do they compare?

Humans are a visual species, so it's not surprising that our eyes work pretty well - though we don't compare to avian. Clark Vision compares the eye to a digital camera, and claims a resolution equivalence of about 580 megapixels, a relatively mediocre ISO 800 sensitivity (and only grayscale for that), roughly f3.5 and @ 20mm focal length, and an awesome (albeit complex) visual range. (Link via Kotke)

It's a great set of references from a photographer and professional astronomer*. I'm not sure how this translates into real time perception however, and that's the bit that matters. I recall reading that the pathways between the retina and the visual cortex have pretty limited bandwidth, and the visual connections to the prefrontal cortex are astoundingly weak. It's as though the world's best camera were connected to your computer by an RS-232 serial cable. There has to be an incredible amount of pre-processing and glossy compression to get any useful real time work, and for us only real time counts. On the other end of the circuit, the brain is doing a lot of informed guessing to create it's simulacra of "reality".

This is why a human studying a photograph will get much more from the image than they can ever perceive from a real time glance. The eye is a marvelous camera, but evolution hasn't had...
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