{"id":909,"date":"2010-05-23T13:25:38","date_gmt":"2010-05-23T00:25:38","guid":{"rendered":"http:\/\/science4all.blogtown.co.nz\/?p=909"},"modified":"2010-05-23T14:19:07","modified_gmt":"2010-05-23T01:19:07","slug":"how-do-we-see-and-remember-the-image-1","status":"publish","type":"post","link":"https:\/\/science4all.blogtown.co.nz\/?p=909","title":{"rendered":"How do we see? (Part1: The Eye)"},"content":{"rendered":"

In some ways the eye is like a camera<\/span><\/strong><\/span>: Its optical elements focus an image of some object on a light-sensitive “film – the retina – while ensuring the correct amount of light to make the proper “exposure”.<\/p>\n

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When your eyelids are open, light enters your eye through a circular hole called the pupil and is focussed by a lens onto the light sensitive retina attached to the back of the eye.<\/span><\/p>\n

The size of the pupil can be adjusted to allow more light to enter when the environment is dim, and less light when it’s bright.\u00a0\u00a0 There are about 126 million sensory cells in the retina, both cone-shaped cells which are color-sensitive and rod-shaped cells which aren’t color-sensitive but can detect low levels of light, useful for night vision.<\/span><\/p>\n

Most cameras work in the same way as the eye – when the <\/span>shutter<\/span><\/strong> is open, light enters a roughly circular hole called the<\/span>aperture<\/span><\/strong> and is focussed by a <\/span>lens<\/span><\/strong> onto a light sensitive medium at the back of the camera, either film or an electronic sensor.\u00a0\u00a0 Some types of camera, like a pinhole camera, don’t have a lens, and some digital cameras don’t have a shutter; nevertheless, understanding how these things work will help make your photographs better. (ref: Flying Kiwi)<\/span><\/p>\n


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