Exposure Control. Controlling the exposure is to control the amount of light exposed to the film when taking a photo.


Lens Diameter

The Lens Diameter, aka D, determines the maximum amount of light that can enter the lens. This is simply the diameter of the opening into the lens and is usually the same as the aperture fully opened. Common lens diameters run from 25mm to 150 mm, with 50mm to 58 mm as the most common.


The Aperture of a lens is a hole that adjusts in size and helps determine how much light is gathered.


The Shutter determines if any light comes in the body at all and for how long. In many modern cameras the mechanism for the aperture and the shutter are the same.

The Shutter Release opens the shutter.

The Shutter Speed determines how long the shutter is held open.

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