How to Know What Aperture to Use: A Guide and A Cheat Sheet

A first step for any budding photographer is getting to grips with the manual settings on their camera. Learning how to properly adjust your lens and gear is the only way to take your shooting to the next level.

Aperture, depth of field, and the shutter speed are all closely related. Changing one can often mean changing the other. While this fact alone can prove overwhelming to many newbies, help is at hand.

This page will dive into the details of how to know what aperture to use, and we’ll talk about depth of field and lens work in photography. From f stops to shutter speed, we’ve got you covered.

What Is Aperture?

In short, the aperture setting you choose determines the amount of light that enters your lens. A small aperture lets in less light, while a larger aperture makes for much brighter photos. The amount of light you let in when shooting determines how ‘sharp’ your final image will look.

The term ‘f stops’, or f number, refers to the number given by your camera when you adjust the aperture.

You might set your aperture to an f stop of f/4.0, for example. There are more complex, accurate definitions of what ‘f stop’ means but as a beginner, the important thing to remember is that when you’re adjusting aperture, you’re changing to a different f stop.

Aperture is directly related to two other photography terms – depth of field and shutter speed.

Depth of Field

Depth of field is the area in which your subject will remain sharp. Once your subject has left this area, it will lose focus and become blurry. A shallow depth of field gives photographers a much smaller area to work with when shooting. The converse is true with a deep depth of field.

As aperture determines the inflow of light, changing it also changes the depth of field you have available. A large aperture creates a shallow depth of field and a small aperture makes your available depth of field deeper.

The image below is a shallow depth of field, as the area in focus is quite narrow, and the background is blurry.


Shutter Speed

Shutter speed is another camera setting that affects the amount of light that enters your lens. The longer your shutter remains open, the more light that enters your system when shooting.

In order to make sure you’re using a setup that’s right for your subject, it’s important to make sure that both your shutter speed and aperture are working together in the way you want them to. They both influence your available light when shooting, so you’ll need to get to grips with both.

One great way to do this, is to use aperture priority mode.

Aperture Priority Mode

Aperture priority mode is a setting on most digital cameras that keeps your aperture and shutter speed settings in sync. Users choose the aperture setting they want and let their camera automatically set an appropriate shutter speed and ISO.

Aperture priority mode is great as it stops the speed of your shutter from interfering with your desired outcome for your shot. Use this mode whenever you want more control over the depth of field for your image.

Shutter Priority Mode

While we’re on the subject, another camera setting that’s worth diving into is shutter priority mode. As the name suggests, this setting gives users control over their shutter settings. In this mode, users choose a speed for their shutter that works for them and their camera automatically picks an aperture that matches.

Shutter priority mode comes in handy when working with moving subjects, as it makes it easier to freeze subjects or slow movement down in an image.

Is Aperture the Same as ISO?

This is a very common question for newbie photographers and it’s important to clear things up. While ISO and aperture are both related to light in photography, they’re not the same thing.

Your chosen aperture literally determines the size of the opening that lets light into your lens. ISO, on the other hand, determines how sensitive your sensor is to light in the first place. In darker environments, a higher ISO makes your lens more sensitive to light, making it easier to get a photo that’s bright enough.

Aperture is about how much light gets in, ISO is about how much light is even needed.

How to Know What Aperture to Use

We’ve now established the relationship between aperture and depth of field. As a general rule, a large aperture creates a shallow depth of field and vice versa. This means that figuring out the right aperture when shooting means knowing the depth of field you want for your shot.

Depth of field is the amount of ‘wiggle room’ you have for keeping subjects in focus. A shallow depth of field doesn’t give you much room at all, while a deeper depth of field gives considerably more room to play with. Different shooting scenarios call for different amounts of ‘wiggle room’.

This means asking questions about your chosen subject. Knowing how much space you need for your subject to stay in focus gets you much closer to an appropriate aperture.

Aperture Settings Cheat Sheet

The section below outlines a number of photography scenarios and the aperture to use alongside them. It’s worth noting that these should be used as a general guide only; circumstances vary from lens to lens and camera to camera.

Landscape Photography

When taking wider shots, it’s typically more appropriate to use a deeper depth of field. This keeps your entire subject nice and sharp. In this case a small aperture, or higher f stop, is what you’ll need.

This type of photography usually calls for an aperture range between f/8 and f/11 with a maximum aperture of around f/16. It goes without saying that each specific set of circumstances is different, so take some time to experiment with your settings and find a setup that works for you.


Portrait Photography

For portrait photography, things are a little different. Keeping a nice blurred background with your model still in focus calls for a shallow depth of field. This means keeping your aperture nice and wide. Use f stops between f/2 and f/6 for a better chance of success.


Macro Photography

When it comes to macro photography, it’s worth being clear on the specific type of photo you’re taking. What many people call macro photography is actually just a close-up shot.

‘True’ macro photography uses a reproduction ratio of 1:1, meaning a subject that appears 10mm across on the camera sensor will appear 10mm in the final image. We’re not saying this to be pedants, the f stop you use will change if you’re taking a ‘true’ macro shot or a close-up photo.

For true macro shots, use an aperture somewhere between f/8 and f/20. For more general close-ups, somewhere between f/3 and f/16 works best.

Night Sky Photography

When shooting at night, you’ll want to let as much light as possible into your lens. When it comes to astrophotography, a large aperture is the way to go. Anything past f/2.8 is considered large. Tweak your settings as you go to figure out what works for your setup.

Remember that a much slower speed is best for your shutter in these environments. Your goal should be to maximize what little light you have available. This means using a higher ISO than usual too.

When You Don’t Know What Aperture to Use

A great setting to choose if you’re completely unsure is somewhere between f/6 and f/8. The resulting depth of field pretty much guarantees that anything you point your camera at will be in focus. When snapping quick holiday photos, for example, this makes things much easier.

Things That Can Influence The Right Aperture

When dealing with things like depth of field and aperture, it’s worth keeping in mind that different camera setups can vary wildly. The lens and camera you use can change things quite a bit.

While the figures given in the ‘cheat sheet’ above are great for a general rule of thumb, mastering photography means learning what to look out for.

Available Light

Changing your aperture and shutter speed means changing the amount of light that comes into your system. For this reason, you should pay close attention to the amount of light that’s available in your scene. An incredibly sunny day or bright studio will need different settings to a darker environment.

The Size of Your Sensor

Each camera sensor comes with its own idiosyncrasies. A setting that gets a certain depth of field with one sensor can produce wildly different results with another. Mastering how to know what aperture to use means learning what works best for your sensor.

Your Camera

Different brands have their own approach to processing images on the fly. Canon in particular stands out in some macro environments, for example. Getting to know your camera is an important part of taking great photos with it.

Questions to Ask When Setting Up

Figuring out the right depth of field and aperture means asking yourself some questions about your scene. Read on for a brief guide to preparing your lens and gear.

What’s My Subject?

What is it that you’re shooting? Considering your chosen subject will make it much easier to make decisions about depth of field and camera settings. How large is your subject? Is it moving, or still? The list goes on. Pay close attention to the subject you’ve chosen and your life as a photographer will become much easier.

How’s My Environment?

Take stock of your scene and its environment. How much natural or artificial light will you have available when shooting? Are you outdoors or indoors? How much space do you have to work with? Questions like these will help you master your environment and pick settings that get the results you need.

How do I Want to Compose My Shot?

Are there particular elements of your scene that you’d to draw focus to? How much of your fore and background do you want to be in focus? Do you think a brighter or darker image would work best for your chosen subject?

The answers to all of these questions will tell you which depth of field you need and therefore which aperture you should use. Remember that a shallow depth of field works well for things like macro photography but will fall short with other subjects.

How Close do I Need to Be?

Maybe you’re capturing the intricate details of an insect’s eye. Perhaps you’re getting photos of a glorious landscape. Your optimal shooting distance will change depending on the photo you’re trying to produce.

Having a good general idea of how close you need your subject to be to your lens will make it easier to find the right aperture.

What Works Best for My Lens?

Your camera sensor and lens also play a big role in which aperture will work best. Getting familiar with your camera setup makes choosing the right settings second nature over time. While this obviously includes quite a bit of trial and error, you’ll get there in the end!


We hope this guide has demystified the process of choosing the right aperture settings for your lens. Remember that aperture priority can be an absolute godsend, especially when you’re first getting to grips with this aspect of taking photos.

Remember that while ISO and aperture are related, they’re not the same thing. Aperture determines how much light gets in, while ISO concerns how much light is even needed in the first place.

Perhaps the most important thing to keep in mind is the relationship between depth of field and aperture. You can’t change your aperture without influencing the amount of your scene that will stay in focus.

Remembering this relationship and experimenting with it will help you become a better photographer.

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