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📷 | Jin Suzuki On his 23rd birthday, "I want to be an independent person while having fun and challenging myself."


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Jin Suzuki On his 23rd birthday, "I want to be an independent person while having fun and challenging myself."

 
If you write the contents roughly
There was a discovery that I like to arrange photos with similar angles of view, so I think I can make use of that in the future.
 

On July 7, Jin Suzuki's first photo exhibition "ZJINE Exhibition" and 22-year-old birthday commemorative original goods ... → Continue reading

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Wikipedia related words

If there is no explanation, there is no corresponding item on Wikipedia.

Draw corner

Draw corner(Gakaku,British: angle of view) IsカメラTaken in写真The range of the scene reflected in角度It is represented by.Is a general visual termField of viewSometimes used without distinction from (field of view).

Incidentally,Viewing angleIn JapaneseViewing angleTranslated as, but hereDraw cornerIs not expressed.this isLiquid crystal displayIn a display device that has the characteristic that the color development and visibility of the screen change depending on the viewpoint position, the range of the viewpoint position where the display can be viewed correctly (the contrast ratio above the reference value can be maintained) is expressed with 0 ° directly in front. It was done.

Calculation of camera angle of view

The angle of view of the camera is a function of the following three parameters.

  1. usePhotographic filmAnd the dimensions of the imaging surface such as optical sensors
  2. Project the image onto the imaging surfacePhoto lens OfFocal length
  3. Degree of lens distortion

If the lens has no distortion, the angle of view is determined by the dimensions of the film or optical sensor and the focal length of the lens.

The angle of view is measured by the following three methods.

  • Horizontal angle of view (from the left edge to the right edge of the frame)
  • Vertical angle of view (from top to bottom of frame)
  • Diagonal angle of view (from one corner of the frame to the other)

With a distortion-free lens, the angle of view (α) Is one of the above three dimensions (d) And the effective focal length (XNUMX), it is calculated as follows.[1].

[2]

The effective focal length is usually the standard focal length (F), ButMacro shootingThen the expansion rate (m) Must be taken into consideration, and there are the following relationships.

Diagonal dimensions are horizontal and verticalPythagorean theoremIs applied, it is calculated as follows.

Where h is the horizontal dimension and v is the vertical dimension.For example, in a 35mm full frame, the diagonals look like this:

Lens type and effect

The type of lens represents the angle of view.

  • Super wide-angle lens, orFisheye lens --Up to 180 ° angle of view (some are even wider)
  • Wide-angle lens --Generally 100 ° to 60 °
  • Standard lens-generally 50 ° to 25 °
  • telescope lens --Generally 15 ° to 10 °
  • Super Telephoto Lens-Generally 8 ° to 1 °

Zoom lensCan mechanically change the focal length and angle of view without changing the lens.

A telephoto lens magnifies the subject and captures distant objects,Depth of fieldBecause it is shallow, the range of focus is narrow.On the other hand, wide-angle lenses tend to increase the distance to the subject, and the depth of field is deep, so the range of focus is wide (Pan focusSuitable for shooting. ).

Further, with a wide-angle lens, perspective distortion is likely to occur when the subject is not facing the subject.For example, if you look up at a building with a wide-angle lens, the image will taper off as the building goes up.On the other hand, when shooting with a standard lens under the same conditions, the range that enters the screen is narrow due to the narrow angle of view, and perspective distortion does not occur as much as with a wide-angle lens.

If the lens is different, in order to shoot the subject at the same size, the distance to the subject must be changed, so changing the angle of view indirectly changes the perspective distortion, and the subject and its foreground It also changes the size ratio to something.

An example of the difference in angle of view depending on the lens.The photo below was taken from a fixed position with a 35mm camera.

Draw corner(angle of view ) angle of coverage Often confused with, the latter term means the angle at which the lens projects onto the focal plane.this isView cameraIt is a term that has only technical meaning in photography.Since the image of the lens is circular in the view camera, it must be projected as a circle larger than the size of the film.In a camera in which the distance between the lens and the film is fixed, the image projected from the lens does not deviate from the imaging surface, and the image is always projected on the entire surface.Therefore, you don't have to worry about the angle of coverage.

Take a circular imageFisheye lensIs an example where the angle of coverage is narrower than usual.The angle of view of a fisheye lens with a circular frame is almost the same as that of a fisheye lens for full-frame photography, but because the angle of the image projected on the film is narrow, it becomes a circular image and the entire film is not used.

Angle of view of main lenses

Focal length and angle of view of 35mm camera

The table below shows the same size as 36mm format SLR (SLR) and 24mm format film in 35mm x 35mm format.Image sensorTo use35mm full sizeFocal length of digital single-lens reflex (DSLR) lens[3]And each angle of view is shown in the table.

In addition, 35mm full size digital single-lens reflex cameraImage sensorThe size of the film may be slightly smaller than that of 35mm film, but it is negligible.

Focal length and angle of view of 35mm SLR / 35mm full-size DSLR
Focal length (mm)14202428355085100105135180200300400500600800(1200)
Diagonal (°)114.294.584.175.463.446.828.624.423.318.213.712.368.256.194.964.133.10(2.07)
Vertical (°)81.261.953.146.437.827.016.113.713.010.27.636.874.583.442.752.291.72(1.15)
Horizontal (°)104.384.073.765.554.439.623.920.419.515.211.410.296.875.154.123.442.58(1.72)

35mm equivalent focal length image for each format

APS-H size-APS-C size-Four Thirds System(Micro Four Thirds System) DSLR has a smaller image sensor size and a narrower angle of view with respect to the focal length than the 35mm full-size DSLR.Therefore, the focal length image (effective shooting angle of view) converted to the 35mm format is from the telephoto.

Conversion to the focal length of 35mm format can be obtained by multiplying by a coefficient calculated from the effective size of the image sensor (some people express it as an "approximate value" because the effective size is slightly different for each camera model). ..

3D digital art

Three-dimensional computer graphicsTo display a 3D model on a 2D screen3D projectionA series of mathematical calculations are performed for this purpose. The angle of view of 3D graphics is therefore easily changed depending on the setting, and some software expresses the angle of view by the focal length of a fictitious lens. An angle of view of 90 ° or more is possible, and a fisheye lens-like effect can be easily realized.

Cinematography

One of the shooting techniques for movies and televisions is to intentionally change the angle of view by zooming.Camera work that narrows the angle of viewZoom inOr, camera work that widens the angle of view.

video game

In subjective viewpoint games (especially racing games), the angle of view is widened to 90 ° or more to intentionally make the projected world look wider and to increase the perceived speed.This can be done gradually, for example in conjunction with speeding up, or with some sort of "turbo boost" setting to get into that state.This is an interesting visual effect in itself, but at the same time itGame engine,hardwareIt is possible to express speed more than the performance of.For exampleGrand Theft Auto: San AndreasSuch a technique is used in.

First-person shooterPlayers may try to widen the angle of view (20 ° to 30 ° wider than usual) and see the surroundings over a wider area.

footnote

  1. ^ The angle of view calculation is more complicated with a distorted lens and is not very useful in practice.
  2. ^ As is clear from the trigonometric function, the angle of view and the focal length are not in a linear relationship.For this reason, with a wide-angle lens, the angle of view changes significantly with a slight change in the focal length, and with a telephoto lens, it does not change much.Roughly speakingInverse proportionalSince it can be approximated by, it is easy to make an approximation if one angle of view is memorized.
  3. ^ The focal length of the lens is based on the 2010mm format single focus lens released by Canon, Nikon, and Sony as of 35.

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