What is aperture priority mode?
Aperture priority mode is one of the semi automatic modes in your digital camera. In automatic mode, the camera takes the decision for you to make a standard exposure. But, in semi automatic modes, you can change one (or more) setting and the camera does the rest of the job.
Semi automatic modes like aperture priority and shutter priority modes are available in all DSLRs and in some advanced point and shoot cameras. In aperture priority mode, you can change the aperture, and the camera selects the other exposure parameters (ISO, shutter speed) for getting the exposure you want. So what is the need of using this mode? It saves your time and still help you to take creative shots. As you may know, aperture is used to control the amount of light enters the camera and the depth of field or area of focus.
Read: Introduction to Aperture
Why do you need to use the aperture priority mode?
So if you want to control the depth of field in a photograph, you can use this mode. In this video I am explaining what switching to this semi automatic mode does to your camera, and what it can do for your photos.
From this video you will learn:-
1. How to use the aperture priority (A or Av) mode effectively to take creative shots?
2. What is aperture and how it controls the light getting into the camera?
3. How change in aperture values changes the depth of field in your photos?
Relationship between Aperture and Depth of field
The self explanatory images below will help you understand the relationship between aperture and depth of field.
As you can see, the depth of field becomes less shallow (or more area in focus) when the aperture opening is small or vice versa. So if you want more area in focus in your photographs (say, landscape photographs) , use a large F-number or narrow aperture. And if you want only a small area in focus in your photos (say, portrait photographs), use a small f-number or wide aperture.
Below are couple of examples of various photos that I have taken to show you which aperture I used.
I hope you liked the video and find it informative. Please feel free to ask any questions. Check out my youtube channel The Shutter School for more videos and my facebook page Dustin Thompson Photography.