formed

Aperture and shutter (shutter speed) are the two integral parts of the exposure.

In a figurative sense: The water line and the bucket

Like to have a water pipe and a bucket are trying to basically explain the principle. We are no exception, as the example illustrates the situation well in itself.
So, we assume that the tube diameter is the shutter and the valve in the line of closure. Have on one side like a large pipe diameter, on the other a small (= small aperture). Among the two tubes is a bucket. The buckets are to be fully equal in both cases.
If the pipe diameter is large (= large aperture), the valve must be opened only briefly (= fast shutter speed), because water flows out in a short time. With a small diameter (= small aperture), the valve must be open longer (= slow shutter speed), so as to flow the same amount of water in the bucket. The result is the same in both - both are the same bucket full.

But this conceals something we compare (and that is why he is lagging here, we want to apply it to photos): Two identical full buckets are two equally full bucket. If they are replaced, it can not be said, which was filled buckets and how.
In the photo it looks a little different: although there are two images that were exposed with large aperture and higher shutter speeds or with a small aperture and slow shutter speeds, properly exposed, but differ in their statement. With a little experience can roughly say, could have originated with what shutter speed and aperture combination image.

To expose a photo optimally requires the sensor (film) has a certain amount of light. This consists of the following factors: the length of time that the sensor is exposed to light and the amount of light that is incident through the lens. Various combinations of aperture and shutter speed would immediately that the same amount of light falling on the film or sensor.
If the light meter, a certain light value (combination of aperture and shutter) are determined, it is possible, by changing the combinations (of course within the limits suggested by the lighting conditions) have the same exposure, but to achieve different photos.

An example is determined as follows light value: screen 4, shutter speed 1/60 sec.
Similarly, the combination aperture 5.6, shutter speed 1/30 are sec. and f8 at 1/25 sec. lead to a correct exposure. (The combinations would continue as desired, until a combination with the prevailing light conditions are no longer functioning or the combination is no longer the photographer and his camera is to be implemented.)

Any change in shutter speed requires an equal but opposite change the aperture when the shutter will remain the same. The situation and determine the desired effect, the combination of aperture and shutter.
Both values ​​behave in opposite directions. Much light is available to give a short exposure time and vice versa in low light requires a correspondingly long period of exposure.

But why the same correctly exposed images with different aperture-time combinations are different? We now consider the function of both parts.

The iris (aperture, aperture)

The incident light is metered through the orifice, it does so, the effective amount of light that falls on the film or sensor during a particular time.
The optical aperture is continuously varied by overlapping lamellae and works like the pupil of the human eye: In the dark, has widened the pupil, in daylight it closes tighter.
And we must not be guided by the f-numbers on the ice: a small f-number (eg 1.4) is equivalent to a large aperture, large f-number (eg 22) a little.

The panel also has a major influence on the depth of field. What it is and how the panel creates is explained later.

The shutter (shutter speed, exposure time)

The closure limited the incident light is temporally regulated, ie the duration of light incidence.
During the period over which the shutter is open, the light falls on the sensor or film. First of all, the shutter speed ensures that a sufficient amount of light falling on the film / sensor. Some projects are possible but only with certain shutter speeds.

Faster shutter speeds lead to sharper images, but these are inevitable in large aperture combination. Halved for a shortening of the shutter speed by 1 level to the amount of light (and vice versa). Any change in the aperture by 1 level down (eg, aperture 8 to 5.6) leads to a doubling of the amount of light (and vice versa).

What impact can one now on the shutter speed on the result, so take the final image?

The faster an object moves, the shorter the shutter speed needs to be, when the object is sharp. Somehow clear. For pedestrians 1/60 sec is sufficient for a moving train on the other hand it takes even 1/1000 sec, the motion of a subject can be achieved by setting a shutter speed that stopped for a movement is actually too long to be expressed. Then the subject is blurred.
By contrast, the technology helps the Mitziehens: The object is sharp, blur the background. Sure to choose a shutter speed that matches the speed of the object (eg the car). Then point the camera at the subject and moves with it. The course works best in uniform motion. This creates an image that reflects the speed well.
Do you photograph such a fast car with a very fast shutter speed without pulling, you can see from the photo is no longer whether the car was or went. Since then somehow lacks the dynamics.

Propelled vehicle photographed with a short shutter speed. The picture is static, the dynamics is missing.

Propelled vehicle, photographed at higher shutter speeds without entrainment. The background is sharp, the vehicle is out of focus. The motion is clear, but it does not recognize much more from the car.

Propelled vehicle, taken with slow shutter speeds and camera mitgezogener. The car is sharp, the background is blurred. The momentum comes as expressed, in addition to the tire radial blur by fast rotation.

And what makes the panel?

Each lens focuses strictly speaking, only a single level sharply. The aperture then decides how much is shown in front and behind them still sharp. Which brings us now with the depth of field.
The depth of field gets a separate entry , at this point I would say this: If a detail emphasized and the rest will be hidden, is a large aperture (small f-number that is) chosen. If multiple objects into focus the picture, which are at different distances from the camera, is a small aperture (large f-number that is) necessary.

Relationship between aperture and depth of field

For those who want to know more: How are the odd f-numbers?

The f-number indicates how many times the diameter of the lens and the aperture of the iris part of the lens focal length. Gate 2 thus means: The opening diameter of the lens is 2 times included in its focal length. In other words, the focal length is twice as large.

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