# Angular aperture

aperture angle
The angular aperture of a lens is the angular size of the lens aperture as seen from the focal point:wikipedia
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### Angular diameter

apparent diameterangular sizeapparent size
The angular aperture of a lens is the angular size of the lens aperture as seen from the focal point:
In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens).

### Numerical aperture

apertureshigh numerical aperturehyper-NA
In a medium with an index of refraction close to 1, such as air, the angular aperture is approximately equal to twice the numerical aperture of the lens.
In air, the angular aperture of the lens is approximately twice this value (within the paraxial approximation).

### Lens (optics)

lenslensesconvex lens
The angular aperture of a lens is the angular size of the lens aperture as seen from the focal point:

### Aperture

aperturesaperture stoplens aperture
The angular aperture of a lens is the angular size of the lens aperture as seen from the focal point: D is the diameter of the aperture.

### Focus (optics)

focusfocal pointfocusing
The angular aperture of a lens is the angular size of the lens aperture as seen from the focal point:

### Focal length

back focal distanceeffective focal lengthfocal distance
f is the focal length

### Diameter

Ddiameters
D is the diameter of the aperture.

### Refractive index

index of refractionrefractive indicesindices of refraction
In a medium with an index of refraction close to 1, such as air, the angular aperture is approximately equal to twice the numerical aperture of the lens.

### Paraxial approximation

paraxialparaxial opticsparaxial limit
In the paraxial approximation, with a small aperture, D

### F-number

focal ratioaperturef-stop
f-number

### Field of view

FOVfields of viewwide-field
Field of view

### Acceptance angle

Half of the angular aperture of an optical system

### Panavision cameras

Panavision Platinumcameras and lensesPanaflex
Where the Panavision Platinum was mostly an evolution and refinement of the original 1972 Panaflex, the Millennium is a totally new design, having a new twin-sprocket drum incorporated with the movement, major electronics revisions, and a general weight reduction from 24 to 17 lb. The Millennium is capable of 3–50 fps forward and reverse, though reverse running requires a reversing magazine, and it has a focal-plane shutter, the aperture angle of which can be adjusted electronically while the camera is running, between 11.2° and 180°, allowing for four stops of exposure ramping within a shot with no iris adjustment.

### Photon

photonslight quantalight
where θ is the aperture angle of the microscope and λ is the wavelength of the light used to observe the electron.

### Angular resolution

spatial resolutionresolutionresolved
The resolution R (here measured as a distance, not to be confused with the angular resolution of a previous subsection) depends on the angular aperture \alpha: