Cameras, Microscopes and Telescopes: Tools That Extend Our Sight

0:00How do cameras, microscopes and telescopes extend our sight?

0:05A camera's lens is a curved piece of glass or plastic that bends light from the object.

0:12The lens focuses the light into an upside-down image on the sensor, a grid of tiny light detectors.

0:19The aperture is the opening that lets light in. It can widen or narrow to let in more or less light.

0:27Your eye works the same way: your pupil is its aperture, and your retina is its light sensor.

0:34A microscope is for tiny things close by, such as a specimen, the sample you are looking at.

0:41Its light passes through two convex lenses, thicker in the middle than at the edges, and into your eye.

0:49Magnification is how many times bigger something looks: the objective lens magnifies 40 times, the eyepiece 10 times.

0:58Multiply them: 10 times 40 gives a total magnification of 400 times.

1:05A telescope is for faint things that are far away, like a distant star.

1:11Its light arrives spread over a wide area, but your small pupil catches only a little of it.

1:17A telescope's large lens gathers far more of that light and focuses it into your eye, so faint things look brighter.

1:26Many big telescopes use a curved mirror instead of a lens to gather the light.

1:32So magnification is not all that matters: gathering more light matters too.

1:38Cameras focus an image, microscopes magnify tiny things, and telescopes gather faint light.