Many cameras are shipped with Quick Reference Guides. In many cases, you actually have to download the real manual. Paper is expensive, heavy and bulky, in quantity, so camera companies don't want to print it and pack it and ship it. Here's what is said in the GH4 Advanced Guide: (See Attachment).
If you need more than that, you need a book on photography that explains aperture in much greater detail. But you still need to read the manual to understand how YOUR camera deals with the specific feature.
You need something like this from a book I'm writing:
"Attributes of aperture include:
The Lens’ Diaphragm:
• Is analogous to the iris of your eye (the muscles that adjust the pupil size)…
• Is a set of spring-loaded blades that open and close to control the flow of light through the lens aperture…
• Is activated electromechanically by the camera, just before exposure…
• Is adjusted electronically, via a dial on the camera body, or a setting in remote control software…
• Controls the look of “bokeh”— the out-of-focus pattern in the background of images shot with shallow depth of field — Usually, the more blades in the diaphragm, the more pleasing and subtle is the bokeh… Better lenses have diaphragm blades designed specifically to enhance bokeh by creating smoothly rounded overlapping circles in the out-of-focus background pattern.
The Lens’ Aperture:
• Is analogous to the pupil of your eye (the black “hole” in the iris)…
• Is created by, and controlled by the diaphragm…
• Controls the *volume of light* that reaches the sensor during an exposure…
• Is adjusted using a series of f/stops, usually measured in 1/3 stop increments*, with lower numbers letting in more light, and higher numbers letting in less light…
• Controls depth of field, or how much of a scene is in focus, from a near point to a far point within the scene. Depth of field is roughly distributed 1/3 in front of the point of focus and 2/3 behind it…
• Directly affects the sharpness of an image, due to the optical properties and limitations of both the particular lens and the particular camera sensor in use…
• Works in conjunction with Shutter Speed and ISO to control the exposure (the total amount of light energy used to make an image)…
• Can be calculated by an App on your smartphone, tablet, or computer
*The Aperture Scale most commonly includes *0.95,* 1.0, 1.2, *1.4,* 1.6, 1.8, *2,* 2.2, 2.4, *2.8,* 3.2, 3.5, *4,* 4.5, 5.0, *5.6,* 6.3, 7.1, *8,* 9, 10, *11,* 13, 14, *16,* 19, 20, *22*, … , with standard whole stops marked in asterisks here. Real photographers eventually memorize this scale and use it often!
The f/stop itself is expressed as the focal length of the lens divided by the number of times the aperture width will “fit into” the focal length of the lens (i.e.; f/8 at a focal length of 48 mm is 48/8 or 6mm wide; f/8 at a focal length of 96 mm is 96/8 or 12mm wide. Both “f/8 holes” let the same amount of light reach the sensor, which explains why f/stops are useful! f/stops are generally used as constants, regardless of the lens’ focal length or zoom setting. (Yes, the 12mm hole lets in four times as much light, but the focal length doubling from 48 to 96 mm magnifies and spreads that light intensity over a four times greater area, so the net result is the same exposure… Basic math and physics principles apply here.)
f/8 is a calculation! It is not an exact guarantee of light transmission. Two lenses set to f/8 may provide slightly different exposures, due to differences in construction, glass, coatings, groupings of elements, number of elements... Very high end lenses are calibrated in t/stops, indicating they meet stringent standards for light transmission calibration. The scale is the same as f/stops.
Most lenses are sharpest when used about one to three whole f/stops down from maximum aperture. (For example, if maximum aperture is f/2.8, the lens probably performs most sharply when stopped down to between f/4 and f/8.)
Although depth of field increases at progressively smaller apertures, such as f/11 or f/16, overall sharpness decreases at smaller apertures due to diffraction (scattering) of the light. When camera manufacturers add resolution to their sensors without making them bigger, diffraction is noticed at progressively wider, lower-numbered apertures. For example, the 15-megapixel APS-C sensor in a Canon EOS 50D just starts to show diffraction limiting of sharpness at f/7.1! Used at f/32, this camera yields very soft images, even with very good lenses. Used at f/5.6, this camera is amazingly sharp and generally reveals excellent detail from the same lenses. You can see examples of this by reading lens test reviews at
http://www.dpreview.com."If the camera manual explained everything that thoroughly, with illustrations, it would be 2500 pages long!
Many cameras are shipped with Quick Reference Guid... (