Computer Graphics - 3D Computer Graphics
Details goes here
In simple words, Exposure controls, how dark or light an Image will be taken by the Camera. So, Exposure is the amount of light per unit area reaching to the electronic image sensor .
Too much of light will result an Over-Exposed photo (A very bright Image, where most of the stuff in the image will be washed out). Same as the less light will also result an Under-Exposed photo (A dark image).
Mainly a Camera Exposure is tuned by the Aperture, Shutter Speed and ISO. And controlling these three sets of settings allow us to capture optimal photo quality. Also these settings allow us to add special effects like depth-of-field, blurriness, sharpness, in-motion or freeze motion effects to our snapshots.
The Aperture ? (Aperture-Hole) controls the amount of light which can be passed into the camera. And it is the very first important place, where we control our Exposure.
Aperture is controlled by the Lens. So, the Lens has one side that is wide-open; where the light gets in. In the middle, by traveling through the series of lenses; it gets focused. And at the end, it passes the Aperture-Hole (or Iris Opening). So, the effects like Depth-of-Field, Focal Point, Blurriness and Sharpness happened in the Lens first.
Usually a Camera Lens is a combination of multiple lenses arranged togather. If you like, you could read more in detail about Lens Basics (raw) and Camera Lenses as well as Telescope Lenses.