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Canon, Nikon, Sony, Panasonic, Olympus, Pentax, and Leica are well-known brands for cameras. Just a push of a button and click! - the memories of a special day, event, person or place is captured on film or digital. The first permanent photograph of a camera image was made in 1826 by Joseph Nicéphore Niépce.

The three pillars of photography are shutter speed, ISO, and aperture. A camera shutter is a stiff curtain, or plate, in front of the camera sensor or film that stays closed until the camera fires which causes the shutter to open and fully exposing the camera sensor or film to light that passes through the lens. After the sensor or film is done collecting the light, the shutter closes immediately, stopping the light from entering the lens. Whereas an aperture is a hole or an opening through which light travels into the camera based on the allowed amount of light to enter. Once all of that is combined, a clear image of what is being viewed can be seen. 

Much like the camera process, the human eye works in the same way. Light travels through the pupil and onto the retina. The image is then sharpened by the eye lens with the pupil of the eye adjusting itself to the amount of light, whether if it's too bright or dark. As for the camera shutter, it is like the eyelids, which can blink in fractions of a second. The image is then stored in the brain.

The size of the pupil is controlled by the iris. Irises are what give our eyes colour, which is brown, grey, blue, hazel, violet, or green. When the pupils are dilated, they appear big, and when they are constricted, it looks like a tiny black dot.  This is caused by either an excess or lack of light within ones surrounding. When a pupil dilates, it dictates that not enough light is given meanwhile a dilated pupil is the complete opposite. 

 Dilated pupil

Constricted pupil

Experiment: 

To observe the dilation and constriction of the pupil. 

Materials: 

a friend, torchlight, dark room.

Steps:

1. In a dark room, shine a light onto your friend’s eye and observe what happens to the pupil. 

2. Turn the torchlight away and observe what happens to the pupil. 

Glossary of Terms:

Constrict [kuh n-strikt] cause to contract or shrink; compress.

Dilate [di- ley] to make wider or larger; cause to expand.

Retina [ret-n-uh] the innermost layer of the posterior part of the eyeball that receives the image produced by the lens.

Shared by Surain A. Victor

Guest Blogger