the Aperture
Located in the lens, the aperture controls the exposure, or the amount of light passing through the lens of the camera. It is a disk like opening that opens and closes through various designated settings called, f-stops.
An example of full f-stop designation is:
2.8, 4, 5.6, 8, 11, 16, 22, 32.
A photographer has the option of choosing an f-stop number that meets the needs of both the lighting conditions and the aesthetic requirements of the picture about to be recorded. The smaller the f-stop number, the greater the amount of light that passes through the lens. The larger the f-stop number, the less light that passes through the lens. Thus, small f-stop numbers result in a wider opening of the aperture, while large f-stop numbers close-down the aperture to a smaller opening.
The f-stops relate to each other in what is referred to as one-stop intervals. A lower f-stop number allows twice (or 100%) more light to pass through the lens than the next one. F5.6, for example, allows 100% more light through the lens than f8 does. Consequently, f8 lets in half (50%) the amount of light than f5.6. Since light is an ever changing phenomena, the f-stops help the photographer control the light entering the camera during various types of lighting situations. It is important to note that digital cameras often offer in-between f-stops. As an example, an f-stop of f9 would be in between the full stops of f8 and f11. Below is an illustration of the lens opening at specific f-top intervals.
An example of full f-stop designation is:
2.8, 4, 5.6, 8, 11, 16, 22, 32.
A photographer has the option of choosing an f-stop number that meets the needs of both the lighting conditions and the aesthetic requirements of the picture about to be recorded. The smaller the f-stop number, the greater the amount of light that passes through the lens. The larger the f-stop number, the less light that passes through the lens. Thus, small f-stop numbers result in a wider opening of the aperture, while large f-stop numbers close-down the aperture to a smaller opening.
The f-stops relate to each other in what is referred to as one-stop intervals. A lower f-stop number allows twice (or 100%) more light to pass through the lens than the next one. F5.6, for example, allows 100% more light through the lens than f8 does. Consequently, f8 lets in half (50%) the amount of light than f5.6. Since light is an ever changing phenomena, the f-stops help the photographer control the light entering the camera during various types of lighting situations. It is important to note that digital cameras often offer in-between f-stops. As an example, an f-stop of f9 would be in between the full stops of f8 and f11. Below is an illustration of the lens opening at specific f-top intervals.
the Aperture and Depth of Field
What is depth of field? Depth of Field (DOF) is simply the total amount of area that will be photographed when looking through the viewfinder. When we look through the viewfinder we are beginning to translate a three dimensional world into the two-dimensional area of a picture plane. Adjusting the Depth of Field allows us to control what is in focus within the picture plane. When photographers speak about depth of field, they are referring to the area that surrounds the point of focus in the foreground and/ or the background of the photograph.
We can safely assumed, if we focused carefully, that our point of focus will in fact, be in focus. As you might have already experienced, a subject that is two feet away from the camera requires a different focus that one that is thirty feet away. Thus when we focus on a particular point, the rest of the photograph may not necessarily be in focus as well. Adjustable cameras allow us to alter or direct the depth of field in order to achieve the effect we want in our photograph. Depth of field is often referred to as “selective focus” because it allows the photographer to selectively choose what areas of the photograph will be in focus and which areas will be out of focus. This type of control is a very powerful aesthetic tool as it can isolate and bring attention to specific areas of the image while still maintaining the surrounding environment.
There are three factors that affect depth of field:
1. the aperture
2. camera to subject distance
3. focal length of the lens or lens type
The aperture’s effect on depth of field can be understood with a simple rule:
The wider the aperture (or smaller the f-stop number), the less depth of field that is obtained.
For example, a photograph made with an f-stop of 2.8 will have less depth of field than one made with f 11, which means that the foreground and/or background surrounding the point of focus will be out-of-focus at f 2.8, but in focus at f 11.
Another determinant of depth of field is distance. How close or how far away we are to our point of focus has an effect on depth of field. This factor is called, “camera to subject distance”. The rule is simple:
The closer the camera is to the point of focus, the less the depth of field, and vs.
Subjects that are very close to the camera and require macro or close-up accessories present very limited depth of field due to the camera-subject distance being so very close. Distant subjects such as landscapes, allow for extreme sharpness in both foreground and background due to their distant relationship to the camera.
The last factor affecting depth of field is referred to as the focal length of a lens or lens type. Different types of lenses affect depth of field in the following manner:
The longer the focal length of the lens, the less the depth of field.
Thus telephoto lenses, which have a long focal length will have less depth of field than wide-angle lenses, which have a short focal length.
We can safely assumed, if we focused carefully, that our point of focus will in fact, be in focus. As you might have already experienced, a subject that is two feet away from the camera requires a different focus that one that is thirty feet away. Thus when we focus on a particular point, the rest of the photograph may not necessarily be in focus as well. Adjustable cameras allow us to alter or direct the depth of field in order to achieve the effect we want in our photograph. Depth of field is often referred to as “selective focus” because it allows the photographer to selectively choose what areas of the photograph will be in focus and which areas will be out of focus. This type of control is a very powerful aesthetic tool as it can isolate and bring attention to specific areas of the image while still maintaining the surrounding environment.
There are three factors that affect depth of field:
1. the aperture
2. camera to subject distance
3. focal length of the lens or lens type
The aperture’s effect on depth of field can be understood with a simple rule:
The wider the aperture (or smaller the f-stop number), the less depth of field that is obtained.
For example, a photograph made with an f-stop of 2.8 will have less depth of field than one made with f 11, which means that the foreground and/or background surrounding the point of focus will be out-of-focus at f 2.8, but in focus at f 11.
Another determinant of depth of field is distance. How close or how far away we are to our point of focus has an effect on depth of field. This factor is called, “camera to subject distance”. The rule is simple:
The closer the camera is to the point of focus, the less the depth of field, and vs.
Subjects that are very close to the camera and require macro or close-up accessories present very limited depth of field due to the camera-subject distance being so very close. Distant subjects such as landscapes, allow for extreme sharpness in both foreground and background due to their distant relationship to the camera.
The last factor affecting depth of field is referred to as the focal length of a lens or lens type. Different types of lenses affect depth of field in the following manner:
The longer the focal length of the lens, the less the depth of field.
Thus telephoto lenses, which have a long focal length will have less depth of field than wide-angle lenses, which have a short focal length.
The opening of the Aperture affects DOF. Shot at f 2.8.
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The opening of the Aperture affects DOF. Shot at f 16.
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Camera to subject distance affects DOF. This image is shot at f 5.6, but the focus point is close to the camera.
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Camera to subject distance affects DOF. This image is also shot at f 5.6, but the focus point is further from the camera.
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