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Camera VS the Human Eye

The eyes are commonly compared to cameras – their functions are quite similar, both processing light and recording images. Your eyes use light to send image signals to the brain, and cameras use it to capture images.

But how similar is a camera to the human eye?

 

Focal Length

The focal length of the lens determines the angle of view of your camera. Your eyes aren’t quite as simple; although they have a focal length of around 22mm, this isn’t quite as straightforward. The back of the eyes are curved and the periphery of the visual field has less detail than the centre. Your eyes also work together to provide you with a complete image.

The diameter and the focal length of the pupil allows for an easy calculation of the aperture of the eye. A 17mm focal length and an 8mm pupil means that the eye works as an f/2.1 lens. However, this measure doesn’t determine the angle of view of the human vision. The cone of visual attention on the eye is around 55 degrees wide; you would require a 35mm camera with a 43mm lens to provide 55 degrees of angle of view.

Each eye has an angle of view of approximately 120-200° and the overlap of both eyes’ sight is around 130°. On a camera, this angle would distort the image tremendously.

 

Resolution

Your eyes provide an amazing resolution of approximately 130 million pixels, even though only around 6 million of the eyes’ pixels see colour, the rest seeing in black and white. Most digital cameras have around 5-20 megapixels, short of the 52 megapixel equivalent your eyes can achieve.

However, only your central vision can provide such resolution as it is the only 20/20 vision, which means that we can’t achieve such amount of detail with a single glance. The more we move to the periphery of your vision, the more the resolution decreases.

Essentially, with a single glance your eyes are only equivalent to a 5-15 megapixel camera. Unlike cameras, your eyes are unable to record and remember images pixel by pixel, only colour, textures, and contrast on regions of interest your eyes are dragged to – like a person’s face instead of the background.

 

Your Eyes as a Camera

Functioning as the front lens element is your cornea, in conjunction with the lens in your eye behind the iris. The cornea takes the light and bends it through the pupil, and the lens helps your eyes focus the images.

The iris and the pupil are like the aperture of a camera; when contracted, the iris covers but a small, central portion of the lens so that the light entering the eye is adjusted. This allows your eyes to function properly in dim and bright conditions.

Acting like an image sensor chip is your retina. The photoreceptor nerve cells transform light into electrical impulses, sending them to the brain through the optical nerve and helping to receive and perceive an image of what we’re seeing. If the retina, or the ‘film’, is bad, you won’t be able to see a good quality image.

Even though some could argue that cameras capture images better than eyes do, both work in a tremendously advanced way to help us see the world around us. It’s up to you, as a photographer, to utilise both to interpret images in your own individual way.

Here at Camera Exchange Store we want to help you achieve your photography ambitions by exchanging your older model so you can upgrade it for a more modern one. Get in touch with us on 0208 371 4179 to speak to our friendly team; we’re always happy to help!

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