Aperture Explained

Last Updated on April 8, 2021

Aperture is one of the three settings that dictate your image exposure. Once you understand how aperture works you will then be better able to balance you aperture with shutter speed and ISO to attain the exposure you desire.

Learning how to properly utilize aperture settings will also help you be able to achieve more photography effects that will really up your skill set.

Aperture Explained

close up of camera lens

Most people find it helpful to think of aperture in how it compares to the function of the pupil of the eye. Aperture, just like the pupil, lows more light in as it gets wider.

Have you ever noticed how someone’s pupil gets bigger when the lights are low and smaller when they are out in the bright sunlight?

Think of your aperture setting in much the same way.

As you learned in the beginners guide to photography, aperture works along with your camera’s shutter speed and ISO setting to determine you exposure.

Changing the aperture setting adjusts the size of the opening that light enters your lens. The aperture setting you choose is dictated by the lighting in your shooting environment along with the required ISO and shutter speed settings.

You will hear aperture referenced in multiple ways, most commonly people will speak of a wide or narrow aperture, or a large or small aperture. Don’t let this confuse you, we are talking about the same thing.

A wide or large aperture means a setting that allows more light into the lens. Whereas a narrow or small aperture simply means a setting that lets less light into the lens.

Aperture is measure in a very specific way. So let’s move on to how to tell what size an aperture is.

Aperture Sizes and Their Meanings

aperture sizes

If you have ever seen an f stop number then you are familiar with how aperture size is noted. The f stop scale is the measuring system used for our aperture settings.

An f number is simply an f/ followed by the aperture size setting number. The number tells you how wide open your aperture is, and therefore how much light it will allow into your lens. How large or small your aperture is set to will greatly effect the exposure as well as the depth of field of your picture.

The basics to remember is that the lower your f/ number is, the larger your aperture is. And a larger aperture means more light will enter your lens.

The smallest aperture setting your lens can have is f/1.4. This setting is referred to as maximum aperture. As the number gets higher, f/22 for example, the smaller your aperture opening is.

All new to photography should take the time to memorize the f-stop scale. This will help you as you begin to understand aperture and how it relates to lighting. The f-stop scale is as follows.

f/1.4 – f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11- f/16 – f/22

When starting at the widest aperture setting, f/1.4, each f-stop you move up means the aperture opening has decreased by half. Therefor, each step up the scale reduces the amount of light let into the lens by fifty percent.

While it is not important to understand the equation at this point, it is important to note that the numbers for each f-stop are derived mathematically. At this point it is more important to know each f-stop number in order and how it effects the light that enters your lens and not be concerned about the math behind it.

So you might be wondering if I am crazy at this point. Many modern DSLR lenses offer f-stop numbers that are not on this scale. Don’t freak out! These are called 1/3 stops and they are just settings in between the standard aperture settings that allow you finer control over your aperture width.

Calculating your Aperture Area

Calculating your aperture diameter is a higher level understanding topic. It is not critical in taking good shots but I think it is important enough to cover. It will allow you a deeper understanding of your aperture settings.

To find your aperture size you will use the following formula.

Take your lens focal length and divide by it by your f/ number. This will give you the diameter of your aperture opening. If you then divide this number by 2 you will have the radius. At which point you can plug it into the following formula and get your aperture area. Remember that r = the radius.

Area = r²*pi

Aperture’s effects On Exposure

Your aperture size directly impacts the exposure of your images. As noted before, aperture works in conjunction with shutter speed and ISO for creating your exposure.

The wider your aperture is the more exposed your image is going to be. And therefore, the narrower you set your aperture the less exposed your picture will be.

Aperture and Depth of Field

Because of the importance of understanding depth of field I recommend reading the guide to get a full understanding. For this article we will not be getting down and dirty with all the details of the subject.

But it is important to understand that depth of field is a reference to how far away a subject can be while remaining in focus in the foreground and background of an image.

When thinking about depth of field in relation to aperture the key to know is that the larger you set your aperture the shallower your depth of field will be.

On the flip side, when setting a smaller aperture you will create a larger depth of field.

Aperture Setting Guide

When using the aperture setting tips below be sure to understand that this is meant to be a jumping off point. There are no hard and fast rules to aperture. Not only that, I find that experimenting with your settings is a huge part of developing your particular voice as a photographer.

With that out of the way, the following aperture settings will give you a place to start. The more comfortable you become with adjusting your settings for your environment the better your shots will be!

f/1.4: This aperture setting is ideal for shooting in low lighting such as night sky photography. It is often used for those seeking a bokeh blur or a shallow depth of field.

f/2: This aperture is often used for the same situations as above. As far as lenses in this aperture, they are generally significantly less expensive than the f/1.4.

f/2.8: This is another aperture excellent for shooting in low light environments. It is an ideal size for shooting faces in low light as it provides a bit more depth of field. You will find that high end zoom lenses come with this as their largest aperture setting.

f/4: If you plan to shoot portrait photography then this is most likely widest aperture setting you will want to use. It works well when you have medium light available.

f/5.6: This setting is not intended for low light situations. It makes a great setting to pair with bounce flashes.

f/8: This setting is a great choice for situations where you want to get a large group of people in a single frame.

f/11: This aperture setting is a popular choice for portrait shots. It provides sharp images ideal for this style of photography.

f/16: This is the point that comes into play when shooting in bright sunlight conditions. It is a small aperture opening making it only for these high light situations.

f/22: This is the aperture setting most used by professional landscape photographers. It is the smallest opening and ideal for bright still shots.

And there you have it! Once you have these concepts down you will have a better understanding of aperture than most amateur photographers out there. Just like with any aspect of photography, it is important to put your knowledge in action. By getting out there and shooting these concepts will really stick and improve your shots. Happy shooting!