Camera Functions and Depth of Field


Aperture, also known as an F-Stop, is a manual function on a digital camera that determines how much light is let into the camera lens. How big or small the aperture is is measured by a number. The higher the number is, the less light is let into the lens and the more closed in the shutter is. The lower the number, the more light is allowed in meaning the image will be more exposed, and vice versa.


The aperture also determines the focus – the lower the number and the more exposure is let into the lens, the more in focus the forefront will be and the blurrier the background will be. On the other side, the higher the number the more in focus the whole image will be. Not only will the forefront be in focus but they background also.

ISO (International Standards Organisation)

The ISO function is what measures and determines light sensitivity. If the ISO is lower, the sensitivity of the camera is less and if the ISO is higher the more sensitive to light it becomes. You can adjust it according to how much light is in the area you wish to photograph. If the area you want to take a photo of is dim/dark and you want to capture more light, then increasing the ISO will allow for more light sensitivity allowing for a brighter picture. However, it is a good idea to keep the ISO as low as possible as the higher it is the more noise is allowed into the picture, making it a grainier photograph.

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The lower the number, the less light sensitivity and the higher the number the more light sensitivity there is, allowing for either a darker or lighter image.

Shutter Speed

Shutter speed is a creative camera function which can create impressive visual effects. At a fast shutter speed, there is a smaller amount of light exposure and the camera lens is open to light for a shorter amount of time. This means that if you have it at a faster shutter speed setting you’re more likely to capture a still image, and is useful for action and movement photographs. For example, if you photographed a person jumping, at a fast shutter speed you could catch them mid air because the lens was only open for a short period of time capturing that exact second or millisecond. On the other hand, using a slower shutter speed can also be useful and create great photographs. With a slower shutter speed, the more light is let into the lens and the lens is open for longer, meaning that any motion in the photograph may turn out blurry. This can be used effectively, for example if you wanted a photo of a waterfall you could use a slow shutter speed which would blur the motion of the water making it appear smoother. The more seconds or milliseconds the lens is open for, the more motion it will capture and this is why images may turn out less sharp.

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Depth of Field

Depth of field refers to the focal range of the camera lens. Its the measurement of distance that a lens reaches in a photograph, similar to aperture. How sharp objects appear in an image is down to how shallow or deep the depth of field is. A shallow depth of field means that the lens focus extends to only the foreground of the image, and the background is out of focus. For example, an image of objects in a queue with a shallow depth of field would mean that only the front few objects would be in focus and the rest would not be. This can be use effectively to add emphasis to the foreground. On the other hand, a deep depth of field means that the lens extends further and can capture more focus in the whole image. The image is sharper as a whole and none or less of the image is out of focus. For example the second picture below – it captures not just the woman in focus but the whole image showing off the quality of all of the photo. This can be used effectively to show the beauty of the whole photograph.

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Shallow depth of field – the light bulb in the foreground is in focus while the background remains out of focus. (Google images)

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Deep depth of field – the whole image is in focus, both the foreground and the background. The whole image is sharp. If this image was in shallow depth of field, the woman would be in focus but not the background. Because the depth of field is deep, the lens focus reaches the background too so the whole image is in focus. (Google images)


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