In a camera, a diaphragm adjusts the size of the opening for light, the aperture. A diaphragm is analogous to the iris of the human eye.

The thin metal leaves that can be adjusted to control the size of the lens aperture.

a mechanical device in a camera that controls size of aperture of the lens; "the new cameras adjust the diaphragm automatically"

An aperture, of varying size, placed within or before a lens to control exposure.

Another word for aperture. Can also be a type of shutter. Refer to Leaf Shutter.

the device in a lens which allows the aperture size to be made smaller or larger.

is a term used to describe the adjustable aperture of a lens. It controls the amount of light passing into the camera and may be in front of, within or behind the lens.

The device, usually found inside the lens, which uses a set of interleaving blades to control the size of the aperture. (see Aperture)

The adjustable aperture of the lens. It restricts the amount of light allowed into the camera. This term can also be applied to shutter types, i.e. iris diaphragm shutter, which is a set of interposing leaves, which open and close at a variable rate to produce a between-the-lens shutter.

The mechanism controlling the size of the lens opening and therefore the amount of light that reaches the film. It consists of several overlapping metal leaves inside the lens that form a circular opening of variable sizes. (You can see it as you look into the front of the lens.) The size of the opening is referred to as the f-stop or aperture.

Lens opening. A perforated plate or adjustable opening mounted behind or between the elements of a lens used to control the amount of light that reaches the film. Openings are usually calibrated in f-numbers.

A ring or plate with a hole in the center that controls the amount of light entering the camera. An adjustable diaphragm in a lens controls the size of the hole, or aperture, thereby permitting more or less light to pass through the lens to the film.

This is another term for aperture.

diafragma] the mechanical part of the microscope near the condenser lens that regulates the amount of light entering the body tube.

In optics, a diaphragm is a thin opaque structure with an opening (aperture) at its centre. The role of the diaphragm is to stop the passage of light, except for the light passing through the aperture. Thus it is also called a stop (an aperture stop, if it limits the brightness of light reacting the focal plane, or a field stop or flare stop for other uses of diaphragms in lenses).