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Here is a crash course;
Depth of field is the apparent sharp area on the picture. It varies with the aperture. The smaller the aperture (large f number), the larger the depth of field.
The aperture is the opening in the lens diaphragm that lets you control the amount of light that hits the sensor. It also control the depth of field. Small aperture number means large opening and shallow depth of field. Large aperture number (like f:16 or f:22) means small opening and large depth of field. The numbers representing the opening are a fraction of the focal length (like f:22 =1/22 of the focal length)
Focal length is the measure of the distance of the optical center of a lens to the image sensor in millimeters. The longer the focal lenght, the larger the telephoto effect. Note that a longer focal length has a shallower depth of field at a given f number than a short focal length.
the shutter speed is the second mean to control the amount of light that reaches the sensor. The faster the speed, the less light will hit the sensor. At long shutter speed (like 1/30 sec or longer) you will likely see some blurring due to subject or camera (or both) movement.
The usual aperture numbers are f:2.8, 4, 5.6, 8, 11, 16 and 22. Each of these number are a mathematical progression, meaning that at f:11, you have half the light going thru than f:8.
The shutter speeds are going in the same mathematical relation:...1/30, 1/60, 1/125, 1/250...and so on. They halve or double each other, depending wether you are going one way or the other, so if you open your lens from let's say f:8 to f:5.6, you will nseed to put a faster shutter speed (like from 1/60 sec to 1/125 sec) to have the same quantity of light reaching the sensor, but having less depth of field at the same time. I hope you can do something with this crash course.
good luck!
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