Light Using Light

How Do Cameras, Telescopes, and Microscopes Work? A microscope helps you see objects that are nearby. A telescope helps you see objects that are far away.

Cameras A camera records an image of an object. A film camera records the image on film. A digital camera records the image electronically on a sensor.

Both types of cameras follow the same basic principle. The lenses in a camera focus light to form a real, upside-down image in the back of the camera. In many cameras, the lenses automatically move closer to or away from the film or sensor until the image is focused.

To take a photo with a digital camera, you press halfway down on a button called the shutter release. The camera automatically adjusts the amount of light that hits the sensor by changing the size of its opening. The camera also adjusts the amount of time that the sensor is exposed to light.

When you press all the way down on the shutter release, the camera records the final image. The camera stores the final images so that you can transfer them to a computer.

Telescopes Distant objects are difficult to see because light from them has spread out by the time it reaches your eyes. Your eyes are too small to gather much light. A telescope forms enlarged images of distant objects.

Telescopes use lenses or mirrors to collect and focus light from distant objects. The most common use of telescopes is to study objects in space.

There are two main types of telescopes: refracting telescopes and reflecting telescopes. A refracting telescope consists of two convex lenses, one at each end of a tube. The larger lens is called the objective.

The objective gathers the light coming from an object and focuses the rays to form a real image. The convex lens close to your eye is called the eyepiece. The eyepiece magnifies the image so you can see it clearly. The image seen through the refracting telescope is upside down.

A reflecting telescope uses a large concave mirror to gather light. The mirror collects light from distant objects and focuses the rays to form a real image. A small, plane mirror inside the telescope reflects the image to the eyepiece. The images you see through a reflecting telescope are upside down, just like the images seen through a refracting telescope.

Microscopes To look at small, nearby objects, you would use a microscope. A microscope forms enlarged images of tiny objects. A microscope uses a combination of lenses to produce and magnify an image. The specimen is placed near the objective.

The objective forms a real, enlarged image of the specimen. Then the eyepiece enlarges the image even more.

What a View! Lab Homework is pages 126-129