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 2024-06-20 12:43:12

Thus, after applying an electric field to an insulating material, the molecules or atoms of which it is made are deformed such that the centres of mass of the positive and negative charges in it no longer coincide, and this situation arises for certain molecules even in the absence of an external electric field (for example, water molecules). Such an atom or molecule possesses what is called an "electric dipole moment" (induced or spontaneous), a quantity that reflects both the distance between the centres of mass and the absolute value of the displaced charges. If it exists, this dipole moment is carried by each of the "neutral clusters" forming the material, and we define the polarisation vector "P" as the volume-average of the dipole moment. This polarisation P itself creates an electric field E which is superimposed within the material on any initially applied field. In the simplest situations of induced polarisation, the polarisation vector is proportional to the applied electric field "E", the proportionality factor being a second order tensor (a matrix) if the material is anisotropic. Furthermore, if the electric field is strong enough, the reaction of the local charges to the field E is more complex and the relation between P and E is not necessarily linear.

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- linear polarisation for which the electric field vector "points" constantly in a given direction- elliptical polarisation (of which circular polarisation is a special case) for which the electric field vector describes an ellipse.

Shallow depth of field is a great way to bring focus to a specific subject to separate it from its background. Shallow depth of field is commonly used in portrait photography and food photography. It is also great for action photography, such as sports and wildlife photography, because it separates the subject from their chaotic background and allows you to shoot with a quick shutter speed to capture crisp detail in action.

To gain a top-level understanding of how you can achieve shallow or deep depth of field by controlling aperture, here is a quick overview of aperture and its related elements: F-stop, shutter speed, and depth of field.

Simply explained, the term 'depth of field' refers to the area of an image that appears to be in focus. As the distance from the focal point increases, the focus gradually decreases until it appears to be out of focus. In any image, there’s a point of absolute focus and a corresponding region of the image surrounding the subject that appears to be in focus.

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Without getting too technical, it’s important to note that this apparent change in depth of field when applied at a closer or farther distance has everything to do with the portion of the frame that the subject fills. With magnified shots, less of the background is represented in the shot, and the blurred background is magnified, making the image appear to have a shallower depth of field. The inverse effect happens when an image is taken at a farther distance.

If you shoot in anything other than a totally controlled environment, you have to know how to adjust your camera for the changing light. Aperture is the part of the lens that controls the amount of light passing through to the camera’s sensor, and its one of the simplest ways to control the depth of field. You can change the access of light by widening and narrowing the diameter of the opening through which light enters the camera.

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By following these tips outlined above, you should now be able to generally control your depth of field to take the images you want. The more you practice and experiment with aperture, distance, and focal length, the more you’ll be able to fine-tune depth of field in your images to enhance your individual photography style.

Deep depth of field is a great way to bring out detail in a large portion of the frame. Deep depth of field is commonly used in landscape photography to capture elements and textures in the majority of the frame throughout many vertical planes. To capture fine detail and deep depth of field, you should use a wide-angle lens to shoot at a distance and set your f stop at a high number for a small aperture.

Set your f-stop to a low number (for example, f/2.8). This will widen your aperture, and you will allow a lot of light into the lens. To compensate for the flood of light you need to shoot faster by adjusting your shutter speed. Your resulting depth of field will be shallow.

While distance plays a large role in depth of field, knowing how to adjust the f-stop to compensate for distance is often a much more convenient way to achieve your desired depth of field. This is especially true in landscape photography, where moving farther from a subject in any significant way is much more difficult than it is in close-up photography.

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Understanding depth of field is important and can greatly influence your photography; it helps distinguish the foreground from the background to create a focal point that draws the eye and tells it where to look. Knowing how to control depth of field gives you the opportunity to choose how much of (and what parts of) your image you want to bring into focus.

The aperture, as discussed above, is just one element of depth of field. The distance from you to your subject can change your perceived depth of field.

Referring back to the example in the introduction, landscape photographers typically want to capture a deep depth of field, where most of the image is in focus, from the foreground to the background. Portrait photographers typically want a shallow depth of field, where a smaller plane of detail in an image is sharpened, and any distractions in the background that may take away from the detail of the face are blurred.

The property of a light wave that describes the behaviour of the electric and magnetic vectors during its propagation (a light wave being an electromagnetic wave). The polarisation of a light wave gives the directions that the electric field vector (or the magnetic field vector) follows over time or along a given light ray in the orthogonal plane to the wave vector. There are some special cases:

If an image has a deep depth of field, it means its area of perceived focus is a broader and deeper portion of the image. If an image has a shallow depth of field, it means its area of perceived focus is limited to a narrower range.

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Set your f stop to a high number (for example, f/11). This will narrow your aperture, and you will let very little light into the lens. To compensate and to avoid having an underexposed image, you will need to shoot slower by adjusting your shutter speed. Your resulting depth of field will be deep.

As a portrait photographer, you’re most concerned with photographing the unique, defining features of your subject; the bright sparkle in an eye, the freckles on a face, the tiny wrinkle in a chin. Images like this aren’t possible without understanding how to use depth of field (also known as focus range) to bring certain parts of your image into focus and blur out what’s less important.

Wider aperture, when applied at a distance (physically, or with a shorter lens) from the focal point, results in an apparent deeper depth of field than it does when it’s applied to a closer subject.

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Learning to control depth of field will help you bring focus to the most important parts of your images and will greatly improve the technical and aesthetic quality of your photos.

Aperture is not infinite; all lenses have their limits, which are clearly defined by the manufacturer. Manufacturers state a minimum and maximum range that the lens can be shot.

When a free charged particle is placed in an electric field, it is moved by this field under the action of the coulomb force. This is for example what happens with free electrons in a conductor. Not all materials are conductors though, and in most, the charged particles (ions and electrons) are not completely free in their movement, forming clusters (of atoms or molecules) of total charge zero. However, under the action of an external electric field, the individual particles (electrons or ions) will be locally displaced from each other inside these clusters, the particles with opposite electric charges moving in opposite directions (but over limited distances, unlike free charges). We refer to the phenomenon of "charge separation".

Depth of field is not equally distributed around the focal point. It is typically distributed unequally, with about 1/3 of the total field of focus lying in front of the subject, and two-thirds of focus lying behind the subject.

As a landscape photographer, you capture sweeping images of oceans capes, mountainsides, skylines, and wilderness. Your photos thrive on dramatic details viewed from close up and far away: Trees, birds, blades of grass are brought into focus to set the perfect stage.

“Knowing how to control depth of field gives you the opportunity to choose how much of (and what parts of) your image you want to bring into focus.” - Mastin Labs