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Aperture or F-Stop – Beginner’s Guide to DSLR Photography

On 5 Dec, 2013 By With 32 Comments
Canon EOS 350D

Canon EOS 350D

Aperture or f-stop is the first part of many of my beginner’s guide to photography.  In this tutorial, we will take you through the basics of DSLR photography.  Many beginner’s feel overwhelmed after stepping up to DSLR from a point-and-shoot camera.  Hopefully this tutorial will help to alleviate some of that feeling.

Aperture or F-Stop

I believe that manual mode seems difficult for beginner’s because they do not truly understand what it does.  Trying to jump right into shooting manual mode without knowing what the light triangle is, is much like trying to make a marinara with eggs and milk.  If you do not know what is in marinara before you start making it, odds are that you will end up with scrambled eggs.

What is the light triangle?

There is three parts to the light triangle, aperture or f-stop, shutter-speed, and ISO.  What you need to know is that each of these three parts determines how much light hits the sensor inside of your camera.

One Side of the triangle is Aperture or F-Stop

Lets start with aperture or f-stop.  Inside of the lens of the camera, there is a set of blades that allow light to hit the sensor to create an image.  How can you control the amount of light hitting the sensor with these blades?  You would set a different f-stop.  The larger the number is, the less light hits the sensor.  The smaller the number is, the more light hits the sensor. So if you kept the other two sides of the light triangle, shutter-speed and ISO, the same you would make your picture brighter with a lower aperture or f-stop, and make it darker with a higher aperture or f-stop.

Wright Brother's Memorial - Photographer Alex Sablan

Shot at an aperture or f-stop of 1.8.

How much light the aperture or f-stop allows in is only the first thing you need to know about aperture or f-stop.  The other factor how aperture or f-stop effects your image is, depth of field.  What is depth of field(dof), you say?  Depth of field is the area close to your focus point that will remain in focus.  When someone says, “I want a narrow or small depth of field,” they are telling you that they want only the other objects in the picture that are close to where the focus is set, to be in focus.  The further from the point of focus in relation to the camera(front to back, not side to side), the more out of focus those areas will be.

Little Art Theater in Yellow Springs, Ohio - Photographer Alex Sablan

Shot at aperture of f-stop f/11

For example, if you are taking a group photo and are using a low f-stop or small aperture like 1.8, only the people that are directly beside the focal point will be in focus.  Anyone who is behind that focal point and anyone in front of that focal point will be out of focus.

In the photo above, you can see clearly that at a low aperture or f-stop, only the areas closely in front and in back of my focus point are in focus. Whereas in the photo below taken at a mid aperture or f-stop, it is pretty sharp front to back.  You can click on either one to see it larger.

To sum up the first part of the light triangle:

  • Low aperture numbers or f-stops = more light and less depth of field.
  • Higher aperture numbers or f-stops = less light and more depth of field.

Hopefully that clears up one side of the light triangle for you. In the next post we will talk about shutter-speed and how it effects your images. If you still have questions, please leave a comment below.

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