How do photos work

In the dark room, the film that was exposed to the light is again put in a series of chemical baths to eventually create the image. So then how do digital cameras work?

Each sensor is divided up into millions of red, green and blue pixels i. When light hits the pixel, the sensor converts it into energy and a computer built inside of the camera reads just how much energy is being produced.

Measuring how much energy each pixel has allows the sensor to determine what areas of the image are light and dark. Putting the information from all the pixels together, the computer is able to approximate the shapes and colors in the scene. If each pixel is gathering light information, then camera sensors with more megapixels are able to capture more detail. Larger sensors will gather more light, making them better performers for low light scenes.

Packing lots of megapixels into a small sensor actually makes the image quality worse, because those individual pixels are too small. All modern cameras use a lens and sensor or film to record an image.

But why then, can two people take a photograph of the same scene and end up with very different results? A camera is a bit more than a lens and a sensor, and adjusting those extra elements changes the way the final image looks. One way that images become unique is through composition. Adjusting composition is often as easy as moving around in a scene — think moving forward or backwards as well as side to side or even kneeling or standing on a chair.

With zoom lenses, the glass is assembled in a way that allows the user to adjust how close or far away the item appears. On a compact camera, zoom is often done with a small toggle at the top of the camera, while DSLR and mirrorless lenses have a twist control around the lens. Zoom is an excellent tool for cropping out distracting objects. Another important aspect of photography is exposure, or how light or dark the image is, and it relies on a number of different factors that, put together, determine how much light is recorded.

Digital cameras have a built-in meter that measures the amount of light in a scene. Newbie photographers can still adjust the exposure without learning manual modes through exposure compensation.

This feature simply lightens and darkens the image. You can observe this phenomenon with a simple experiment. Light a candle in the dark, and hold a magnifying glass between it and the wall. You will see an upside down image of the candle on the wall. If the real image of the candle does not fall directly on the wall, it will appear somewhat blurry. The light beams from a particular point don't quite converge at this point.

To focus the image, move the magnifying glass closer or farther away from the candle. This is what you're doing when you turn the lens of a camera to focus it -- you're moving it closer or farther away from the film surface.

As you move the lens, you can line up the focused real image of an object so it falls directly on the film surface. You now know that at any one point, a lens bends light beams to a certain total degree, no matter the light beam's angle of entry.

This total "bending angle" is determined by the structure of the lens. In the last section, we saw that at any one point, a lens bends light beams to a certain total degree, no matter the light beam's angle of entry. A lens with a rounder shape a center that extends out farther will have a more acute bending angle. Basically, curving the lens out increases the distance between different points on the lens.

This increases the amount of time that one part of the light wave is moving faster than another part, so the light makes a sharper turn. Increasing the bending angle has an obvious effect.

Light beams from a particular point will converge at a point closer to the lens. In a lens with a flatter shape, light beams will not turn as sharply. Consequently, the light beams will converge farther away from the lens. To put it another way, the focused real image forms farther away from the lens when the lens has a flatter surface.

Increasing the distance between the lens and the real image actually increases the total size of the real image. If you think about it, this makes perfect sense. Think of a projector: As you move the projector farther away from the screen, the image becomes larger. To put it simply, the light beams keep spreading apart as they travel toward the screen. The same basic thing happens in a camera. As the distance between the lens and the real image increases, the light beams spread out more, forming a larger real image.

But the size of the film stays constant. When you attach a very flat lens, it projects a large real image but the film is only exposed to the middle part of it. Basically, the lens zeroes in on the middle of the frame, magnifying a small section of the scene in front of you. A rounder lens produces a smaller real image, so the film surface sees a much wider area of the scene at reduced magnification. Professional cameras let you attach different lenses so you can see the scene at various magnifications.

The magnification power of a lens is described by its focal length. In cameras, the focal length is defined as the distance between the lens and the real image of an object in the far distance the moon for example. A higher focal length number indicates a greater image magnification. Different lenses are suited to different situations. If you're taking a picture of a mountain range, you might want to use a telephoto lens , a lens with an especially long focal length.

This lens lets you zero in on specific elements in the distance, so you can create tighter compositions. If you're taking a close-up portrait, you might use a wide-angle lens. This lens has a much shorter focal length, so it shrinks the scene in front of you. The entire face is exposed to the film even if the subject is only a foot away from the camera. A standard 50 mm camera lens doesn't significantly magnify or shrink the image, making it ideal for shooting objects that aren't especially close or far away.

A camera lens is actually several lenses combined into one unit. A single converging lens could form a real image on the film, but it would be warped by a number of aberrations. One of the most significant warping factors is that different colors of light bend differently when moving through a lens. This chromatic aberration essentially produces an image where the colors are not lined up correctly. Cameras compensate for this using several lenses made of different materials.

The lenses each handle colors differently, and when you combine them in a certain way, the colors are realigned. In a zoom lens , you can move different lens elements back and forth. By changing the distance between particular lenses, you can adjust the magnification power -- the focal length -- of the lens as a whole. The chemical component in a traditional camera is film. Essentially, when you expose film to a real image , it makes a chemical record of the pattern of light.

It does this with a collection of tiny light-sensitive grains, spread out in a chemical suspension on a strip of plastic. When exposed to light, the grains undergo a chemical reaction. Once the roll is finished, the film is developed -- it is exposed to other chemicals, which react with the light-sensitive grains. In black and white film, the developer chemicals darken the grains that were exposed to light. This produces a negative, where lighter areas appear darker and darker areas appear lighter, which is then converted into a positive image in printing.

Color film has three different layers of light-sensitive materials, which respond, in turn, to red, green and blue.

When the film is developed, these layers are exposed to chemicals that dye the layers of film. When you overlay the color information from all three layers, you get a full-color negative.

For an in-depth description of this entire process, check out How Photographic Film Works. So far, we've looked at the basic idea of photography -- you create a real image with a converging lens, and you record the light pattern of this real image on a layer of light-sensitive material.

Conceptually, this is all that's involved in taking a picture. But to capture a clear image, you have to carefully control how everything comes together. Obviously, if you were to lay a piece of film on the ground and focus a real image onto it with a converging lens, you wouldn't get any kind of usable picture. Out in the open, every grain in the film would be completely exposed to light. And without any contrasting unexposed areas, there's no picture.

To capture an image, you have to keep the film in complete darkness until it's time to take the picture. Then, when you want to record an image, you let some light in. At its most basic level, this is all the body of a camera is -- a sealed box with a shutter that opens and closes between the lens and film.

In fact, the term camera is shortened from camera obscura , literally "dark room" in Latin. For the picture to come out right, you have to precisely control how much light hits the film. If you let too much light in, too many grains will react, and the picture will appear washed out. If you don't let enough light hit the film, too few grains will react, and the picture will be too dark.

In the next section, we'll look at the different camera mechanisms that let you adjust the exposure. As it turns out, the term photography describes the photographic process quite accurately. Sir John Herschel, a 19th century astronomer and one of the first photographers, came up with the term in The term is a combination of two Greek words -- photos meaning light and graphein meaning writing or drawing.

The term camera comes from camera obscura , Latin for "dark room. A traditional camera obscura was a dark room with light shining through a lens or tiny hole in the wall. Light passed through the hole, forming an upside-down real image on the opposite wall.

This effect was very popular with artists, scientists and curious spectators. In the last section, we saw that you need to carefully control the film's exposure to light, or your picture will come out too dark or too bright. So how do you adjust this exposure level? You have to consider two major factors:. To increase or decrease the amount of light passing through the lens, you have to change the size of the aperture -- the lens opening.

This is the job of the iris diaphragm , a series of overlapping metal plates that can fold in on each other or expand out. Essentially, this mechanism works the same way as the iris in your eye -- it opens or closes in a circle, to shrink or expand the diameter of the lens. When the lens is smaller, it captures less light, and when it is larger, it captures more light.

As you hold the camera to your eye, you wait for just the right moment. Your dog stops for just a moment and snap! You've got your shot. When you press the button on a camera, the mirror flips out of the way. Light then passes onto the back of the camera where it hits photographic film and starts a chemical reaction. When you click the button, you instantaneously record the reflected light off objects in the camera's field of view.

Though you probably can't tell, film consists of a thin sheet of plastic coated with tiny silver crystals in a gelatin. The crystals react to light that passes through the camera and onto the film. Once you've captured your photo, it's time to develop the film in a darkroom. The development process involves dipping the film in several chemicals.

If you have ever held developed film up to the light, you may notice that something looks strange. Developed film gives you a negative image! This means dark objects will look light and light objects will look dark. When it's time to print your photo, you must shine a light through the negative film. This creates a shadow on special photosensitive paper, leaving an image that is the opposite of the negative — a positive print! At last you have your photograph.

I scream, you scream Ready to make a first impression? Even without a camera, you can make a photo by using light from indoor lamps or even the rays of the sun. Experiment by placing different objects on special photosensitive paper to find out what kinds of interesting and beautiful patterns you can capture on your solar-powered prints. Visit Sunprint. Since you're talking about a screen, I'm assuming you're talking about a digital camera as opposed to a film camera, what this article describes.

Electronics stop working when they come in contact with water because of particles dissolved in the water called ions. Those particles mess up electricity, causing it to go places it's not supposed to. Basically, water screws up electronics.

The screen is probably blue because it's broken. Oh, and by the way, water isn't blue. It appears that way because of phenomena having to do with light.

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