-FOCUS-[OPTICS]

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-as of [3 JANUARY 2024]

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___*aka*___

“IMAGE POINT”

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-FOCAL LENGTH-

-[AUTO-FOCUS]-

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-in ‘geo-metrical optics’, a ‘focus’ is a point where ‘light rays’ originating from a point on the object ‘converge’-

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Although the focus is conceptually a point, physically the focus has a spatial extent, called the ‘blur circle’

This non-ideal focusing may be caused by aberrations of the imaging optics.

In the absence of significant aberrations, the smallest possible blur circle is the Airy disc, which is caused by diffraction from the optical system’s aperture.

Aberrations tend worsen as the aperture diameter increases, while the Airy circle is smallest for large apertures.

An image, or image point or region, is in focus if light from object points is converged almost as much as possible in the image, and out of focus if light is not well converged.

The border between these is sometimes defined using a “circle of confusion” criterion.

A principal focus or focal point is a special focus:

For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused.

Since light can pass through a lens in either direction, a lens has two focal points โ€“ one on each side.

The distance in air from the lens or mirror’s principal plane to the focus is called the focal length.

Elliptical mirrors have two focal points:

light that passes through one of these before striking the mirror is reflected such that it passes through the other.

The focus of a hyperbolic mirror is either of two points which have the property that light from one is reflected as if it came from the other.

Diverging (negative) lenses and convex mirrors do not focus a collimated beam to a point.

Instead, the focus is the point from which the light appears to be emanating, after it travels through the lens or reflects from the mirror.

A convex parabolic mirror will reflect a beam of collimated light to make it appear as if it were radiating from the focal point,

or conversely, reflect rays directed toward the focus as a collimated beam.

A convex elliptical mirror will reflect light directed towards one focus as if it were radiating from the other focus, both of which are behind the mirror.

A convex hyperbolic mirror will reflect rays emanating from the focal point in front of the mirror as if they were emanating from the focal point behind the mirror.

Conversely, it can focus rays directed at the focal point that is behind the mirror towards the focal point that is in front of the mirror as in a Cassegrain telescope

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See also

Autofocus

Cardinal point (optics)

Defocus aberration

Depth of field

Depth of focus

Far point

Focus (geometry)

Fixed focus

Bokeh

Focus stacking

Focal Plane

Manual focus

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References

^ “Standard Microscopy Terminology”. University of Minnesota Characterization Facility website. Archived from the original on 2008-03-02. Retrieved 2006-04-21.

en.wikipedia.org /wiki/Focus_(optics)

Focus (optics)

Contributors to Wikimedia projects3-4 minutes 10/1/2004

(Redirected from Camera focus)

Eye focusing ideally collects all light rays from a point on an object into a corresponding point on the retina.

A demonstration of camera focus on different distances, showing a bamboo rooftop

Text on a page that is partially in focus, but mostly not in varying degrees

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*๐Ÿ‘จโ€๐Ÿ”ฌ๐Ÿ•ต๏ธโ€โ™€๏ธ๐Ÿ™‡โ€โ™€๏ธ*SKETCHES*๐Ÿ™‡โ€โ™‚๏ธ๐Ÿ‘ฉโ€๐Ÿ”ฌ๐Ÿ•ต๏ธโ€โ™‚๏ธ*

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๐Ÿ“š๐Ÿ“–|/\-*WIKI-LINK*-/\|๐Ÿ“–๐Ÿ“š

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๐Ÿ‘ˆ๐Ÿ‘ˆ๐Ÿ‘ˆโ˜œ*-FOTOGRAFIA-* โ˜ž ๐Ÿ‘‰๐Ÿ‘‰๐Ÿ‘‰

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๐Ÿ’•๐Ÿ’๐Ÿ’–๐Ÿ’“๐Ÿ–ค๐Ÿ’™๐Ÿ–ค๐Ÿ’™๐Ÿ–ค๐Ÿ’™๐Ÿ–คโค๏ธ๐Ÿ’š๐Ÿ’›๐Ÿงกโฃ๏ธ๐Ÿ’ž๐Ÿ’”๐Ÿ’˜โฃ๏ธ๐Ÿงก๐Ÿ’›๐Ÿ’šโค๏ธ๐Ÿ–ค๐Ÿ’œ๐Ÿ–ค๐Ÿ’™๐Ÿ–ค๐Ÿ’™๐Ÿ–ค๐Ÿ’—๐Ÿ’–๐Ÿ’๐Ÿ’˜

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*๐ŸŒˆโœจ *TABLE OF CONTENTS* โœจ๐ŸŒท*

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๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ*we won the war* ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ๐Ÿ”ฅ