Aperture is just one setting that makes up your exposure, but once you understand it you can drastically change how your image looks. In this video by B & H, aperture is explained in the simplest way possible—from why the numbers are what they are and how it works to how different apertures affect your photos:
What is Aperture?
Simple Definition of Aperture: the opening that light goes through to land on your camera’s image sensor to make a picture
When you change the size of the opening, it changes your exposure in a few different ways.
Beginner photographers may have trouble understanding aperture at first, because the bigger the number, the smaller the opening and vice versa. So, the backwards system works like this:
f/1.0 = really big opening
f/22 = really small opening
F-stop: the number that says how big the opening is
Stopping Down: Changing the aperture to let in less light. If you shrink the opening so half as much light gets through, you are stopping down (f/1 > f/1.4 > f/2…).
Full Stop Settings: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64
Aperture Ring: a rotating ring on the lens barrel that allows manual adjustment of f-stops
Fast Glass: wide maximum aperture lenses like f/2.8 or f/2 and wider
Generally speaking, f-stops start at f/1.0, but that doesn’t mean your camera lens is able to go there. Lenses come in a range of f-stops—not all lenses can go as wide as f/1.0 or as narrow as f/32, but rather fall somewhere in between.
For example, if your lens says f/2.8, that refers to the widest, or maximum, aperture. Or maybe you have a zoom lens called an 18–135mm f/3.5-5.6; which means the lens zooms from 18mm to 135mm and the maximum aperture of f/3.5 is going to be at the wide end of your zoom—that 18mm range. Then when you zoom in to 135mm, your maximum aperture will be f/5.6, and if the zoom is in between then your max aperture is also somewhere in between. The minimum aperture doesn’t change no matter where you zoom.
Most camera aperture settings are in third stop increments, giving you fractional settings in between the full stop settings. Some lenses can even be wider than f/1 but that’s pretty rare.
Wide aperture lenses let in lots of light, allowing you to use a faster shutter speed.
What Happens When You Change the Aperture
In a portrait, a really wide aperture like f/1.4 can flatten the depth of field dramatically. The focus can be shallow and only the eyes can be in focus while the ears are a little softer and the background blurry.
With landscape photography, you want to go narrower, like f/8 or f/11 to get everything from the foreground to background in focus. If you go to a high aperture, like f/22 or f/32, bright points of light will have beams coming off of them.
Once you understand aperture, you can start using the Aperture Priority mode on your camera, which allows you to choose your aperture while the camera does the rest so you get a proper exposure.
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