If I ask you what your lens aperture is set to, you can reply f/8 and that gives me a pretty good idea about the width of the opening in your lens. Here's the key to understanding aperture measurements: SMALL f-stop numbers represent WIDE apertures.
http://www.digital-slr-guide.com/lens-aperture.html
A smaller f-stop means a larger aperture, while a larger f-stop means a smaller aperture. Most people find this awkward, since we are used to having larger numbers represent larger values, but not in this case. For example, f/1.4 is larger than f/2.0 and much larger than f/8.0.
https://photographylife.com/what-is-aperture-in-photography/
The Mighty F-Stop. Think of the f-stop as a unit of measurement like hours (time), meters (distance) or grams (weight). If I ask you what your lens aperture is set to, you can reply f/8 and that gives me a pretty good idea about the width of the opening in your lens. Here's the key to understanding aperture measurements: 1  SMALL f-stop numbers represent WIDE apertures.  LARGE f-stop numbers represent NARROW apertures.
http://www.digital-slr-guide.com/lens-aperture.html
Setting Exposure: Shutter Speed and Aperture. Two of the factors that determine exposure—and thus the brightness of your photographs—are shutter speed and aperture (the other important factor in determining exposure is ISO sensitivity, but in the discussion that follows we will assume that ISO sensitivity is fixed). Shutter speed is the time the shutter is open.
http://imaging.nikon.com/lineup/dslr/basics/04/02.htm
2) Size of Aperture – Large vs Small Aperture. The iris of the lens that controls the size (diameter) of the aperture is called “diaphragm” in optics. The sole purpose of the diaphragm is to block or stop all light, with the exception of the light that goes through the aperture. In photography, aperture is expressed in f-numbers (for example f/5.6).
https://photographylife.com/what-is-aperture-in-photography/
As you can see, just changing the aperture from f/2.8 to f/8.0 has a big effect on how much of WALL-E is in focus and how visible the background gets. If I had used a much smaller aperture such as f/32 in this shot, the background would be as visible as WALL-E.
https://photographylife.com/what-is-aperture-in-photography/
The higher the f-number, the darker the image projected on the image sensor, and the darker the resulting photograph. On the other hand, the lower the f-number, the brighter the image projected on the image sensor, and the brighter the resulting photograph. Exposure is determined by the combination of shutter speed and aperture (f-number).
http://imaging.nikon.com/lineup/dslr/basics/04/02.htm
The lens aperture is usually specified as an f-number, the ratio of focal length to effective aperture diameter. A lens typically has a set of marked f-stops that the f-number can be set to. A lower f-number denotes a greater aperture opening which allows more light to reach the film or image sensor.
https://en.wikipedia.org/wiki/Aperture
The lens aperture – also known as the opening in the lens – plays a critical role in every single photo that you take. When you take control of aperture, you're giving yourself a great deal of creative freedom and you get to decide exactly how your photos look.
http://www.digital-slr-guide.com/lens-aperture.html
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane.
https://en.wikipedia.org/wiki/Aperture
what is aperture in dslr
In Digital Single Lens Reflex, an aperture is a hole or an opening through which light travels. The aperture is a hole or an opening through which light travels in DSLR.