Photography & Imaging

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Diffraction-Limited Spot

Smallest resolvable spot size set by diffraction at aperture N.

Formula

d = 2.44 \lambda N

Variables

dAiry disk diameter (µm)

λWavelength (µm)

NF-number

Example

λ=0.55 µm, N=16: d ≈ 21.5 µm

Did You Know?

Stopping down too far (f/22+) actually softens photos because diffraction blurs fine detail.

photography diffraction sharpness

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F-Number

Aperture f-number is focal length divided by aperture diameter.

Exposure Value (EV)

Combines aperture and shutter speed into one exposure figure.

Depth of Field (approx.)

Range of distances that appear acceptably sharp.

Hyperfocal Distance

Focus distance that keeps everything from H/2 to infinity sharp.

Lens Magnification

Image magnification from focal length and subject distance.

Angle of View

Field of view from sensor size and focal length.