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Video tutorial to set up "aperture / aperture" for learners to take photos

This is a Video to talk about "aperture of the lens".

As you know, the aperture is the aperture of the lens to let light into the camera, and can be adjusted. The more it expands, the more light it enters and vice versa. Change the exposure value by adjusting the aperture, ie you are changing size of aperture. And, when changed the size of the aperture / aperture of the lens What will happen?

Video: Aperture of the lens


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What is the F value?
The measurement of the aperture that you often hear is F and that F is the size of the aperture compared to the focal length (the value of a lens F is the ratio of the focal length divided by the aperture diameter degrees). This calculation makes it an inverse ratio or value, meaning the larger the aperture, the smaller the measurement, and vice versa. For example, f / 4 is less than f / 8 so f / 4 is larger than f / 8. Next, different types of lenses have different maximum and minimum aperture values. With this in mind, these are common aperture values, because some lenses have larger apertures like f / 095, f / 1.2, f / 1.8 … these are common ranges of aperture values must remember:

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The amount of light passing through the lens
When it comes to the amount of light that passes through a lens, people rely on the maximum aperture of that lens. The aperture of a lens here refers to the diameter of the dimmer door inside each lens. It can be opened large or closed small. That diameter is expressed by an f-number, such as f / 2.8 or f / 16. The f-number of a lens is a mathematical expression used to determine the aperture of all lenses with different focal lengths and the same amount of light output.

  • The lower the f-number, the larger the aperture will be. With the larger aperture opened, more light reaches the sensor. The "large open" aperture is: f / 1.4 or f / 2.8.
  • The higher the f-number, the smaller the aperture will be. With the smaller the aperture, the less light enters the sensor. "Small" apertures are: f / 16 or f / 22.

Have you ever heard sentences like "the image is a bit underexposed, opens an aperture" or "the image is a bit overexposed, the aperture is reduced". In photography, we face deals when it comes to exposure. For example, how can we price a change size of aperture compared to time of shutter speed? And then, how do we plan it? sensitivity of the image sensor (or film) when compared to the other two adjustments? The concept of 'stop' is the way we use it to select those parameters appropriately. Understanding that nature is a prerequisite for mastering your camera and controlling the exposure process. Remember that your camera can be designed to change values ​​by 1 / 3rd stop. Therefore, for example, your camera will not switch directly from f / 5.6 to f / 8.0. Instead, it will change from f / 5.6> f / 6.3> f / 7.1> f / 8.0 when you click the control knob. And, I still often "force" a few students studying film shooting before to memorize aperture range, shutter speed range, ISO range so.

A / Av shooting mode – aperture priority

Things to remember regarding mode A on the camera:

  • A – when selecting A mode is not true Auto shooting mode Auto shooting is fully automatic, entrusting everything to the camera for processing, which A stands for Aperture Priority, meaning LENS lens priority.
  • A – when shooting in A mode, the photographer wants to choose the LENS Aperture on their own accord. Which lens aperture is the factor Directly affecting DOF. (DOF – Depth of Field abbreviation that people take or call it "caps" or "sparks". It is simply a word for expressing a clear picture space and what is outside the sharp range in the image. For your subject to be clear, it must be within the DOF of the image. When you focus, on a straight line we see beyond the point that you want to focus, some points in front of that point and behind that point are also clear, that clear image area is called the DOF range.)
  • A – when you shoot in A mode, you want to have the DOF as you like, Clear picture space in the photo thick or thin at will. That is, do not care about the corresponding shutter speed, static or dynamic subjects, even let ISO Auto let the device automatically measure and select the corresponding ISO regardless of the smoothness or noise.
  • A – Want to be the owner of DOF, choose A mode, change the aperture parameters as you like, press take!

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The larger the aperture (the smaller the F number) the DOF range will be less / less / shallow and vice versa. For example, if you shoot at an aperture of f / 2.8, the DOF will be less (more shallow, thinner) than taken at an aperture of f / 22 (thicker, deeper) if shooting on the same subject, the same shooting distance and the same lighting conditions. Usually to understand it we need to remember as follows:

  • Large aperture = small F-number = thin DOF
  • Small aperture = large F number = deep DOF

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Select mode A to master the DOF
Observe the parameters to draw the principle, to proactively customize as you like, not asking for the parameter to capture the same parameter is to get the exact same picture.

  • Camera settings in shooting mode A – aperture priority.
  • Choose a subject to shoot, so it is a stationary subject such as a house corner, trees, etc.
  • Rotate the aperture dial from small to large f-numbers, such as: f / 2.8 – 4, 5.6, 8, 11, 16 … and capture the same subject, focus at the same point, at 1 position position and focus.
  • Copy all the pictures to the computer, review shooting parameters, especially the F – lens aperture.
  • Observe the DOF

Other factors affecting DOF:
We are talking about shooting mode A, which prioritizes the choice of lens aperture to master the DOF. However, there are two other factors that affect DOF, so it should be said here for new players: That is the focal length of the lens and the distance from the position of the camera to the subject being photographed.

Closed-lens focal length is the distance from the center of the lens to the sensor / film surface. Depending on the focal length of the lens, the depth of field of the image will make the image no longer like the eye in the actual scene. With an average lens, the depth of field is almost the same as the eye, but with a telephoto lens (long focal length), the depth of field will shrink, the image has a background closer to the actual scene, the layers photos close together; Whereas with wide-angle lens (wide), the depth of field is pushed away, the resulting image has a farther background than the real scene, the space feels wider than reality.

In short just remember:

  • About lens aperture:
    • Large aperture = small F-number = thin / shallow DOF.
    • Small aperture = large F number = deep / thick DOF.
  • About lens focal length:
    • The longer the lens focal length, the thinner / shallow DOF range.
    • The shorter the focal length, the deeper / thick the DOF.
  • About the distance from the camera to the subject:
  • The closer the lens is to the subject, the thinner / shallow DOF.
  • The farther this distance is, the deeper / thicker the DOF will be.

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