# 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

### 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: