This question and answer are from my answers to Quora. I highly recommend taking the time to further research aperture before you write your response to this request (additional reading can be found here: aperture).
Aperture refers to the size of the opening (the pupil) in specific camera lens that adjusts how much light passes through it when focusing on an image. A small, narrow opening will only let a little bit of light in while a large, wide opening lets a lot of light in. The value of f-stops (where f is a number like f\/16 or f\/8; 1 stop is roughly equivalent to ISO one stop minus your usual ISO setting) is different with each format\/camera format or even manufacturer, so you cannot substitute one for another easily and these numbers rarely match up exactly. Heck, some cameras automatically adjust the depth of field based on which focus point is active! So there’s a lot more than just this whole aperture business going on! RecommendationThis is a short movie about what is aperture in photography. Let’s watch it together. If you have any questions, please reply to this news video.
Camera Obscura Definition
The closest forerunner of the camera was the Camera Obscura. The underlying principle behind the camera obscura (Latin for "dark chamber"), also know as " the pinhole image ," was the observation of the natural phenomenon:
Next, let us look at the brief history of the development of light-sensitive materials and early Photography before reaching the fixed image stage. Though the knowledge of light-sensitive materials existed before, there are no records preceding 1725 of any idea, even closely resembling Photography.
First Picture Ever Taken
The problem to fix the image to the medium had remained unsolved until Joseph Niepce successfully created the first Photograph using a pewter plate coated with bitumen. He later worked with Louis Daguerre to reduce the long exposure times.
Photography On Paper
Let us now look at some of the notable early works directed towards having a photographic image on paper.
The Improved Daguerreotype
The original Daguerre’s process had very slow speed, with exposure times of more than 20 minutes. This made it unsuitable for portraiture. It was only used for still life photography and landscape imagery.