When you’re first starting out in photography all the technical terms can be super overwhelming. It also might seem like there are a million little things you need to worry about. All just to take a decent photograph. However, there are really only three things you need to think about when you’re first learning: shutter speed, ISO, and aperture. But what is aperture and how does it relate to shutter speed and ISO? And how does it affect your overall image?

What is Aperture Anyway?

1/250 sec at f/11, ISO 200

So what is aperture and why is it important? Aperture is one of the most important settings on your camera and works together with shutter speed and ISO to determine exposure. In the most basic sense, Aperture is how wide or narrow the little hole in your lens is. This little hole helps control how much light is hitting the sensor on your camera. And this helps determine how bright or dark your image turns out. It’s a bit like how the pupil of your eye changes size to let in more or less light depending on how bright it is.

What is f-stop?

From Wikipedia

I’m trying really hard not to get too technical in this post because it’s really not my forte, but we do have to talk about f-stops and all that.

Okay, so what is f-stop and how does it relate to aperture? The f-stop is the value that your aperture is set to. You’ll see this denoted on your camera’s screen as f2.8 or f/5.6 or whatever you have it set to.

Here is where it can get confusing:

The larger the number of your f-stop, the smaller the opening of your aperture. Which means, the smaller the number of your f-stop, the larger the opening of your aperture. This is because this value is actually a fraction. So f/2.8 means the aperture is opened pretty wide, while f/16 means the aperture is fairly closed.

Aperture, Shutter Speed and ISO

Aperture, shutter speed and ISO all work together to create the correct exposure when you snap a photo. When you’re in full manual mode, you have full control over all three of these aspects. However, when you are shooting in aperture priority mode, you only have control over aperture and possibly ISO depending on your settings.

So, a few things to remember:

  • A faster shutter speed means less time for your camera to gather light, so you will probably need a wider aperture and higher ISO
  • A slower shutter speed means more time for your camera to gather light, so you can a narrower aperture and lower ISO
  • A higher ISO means your image will appear brighter so your shutter speed can be a bit faster and your aperture a bit narrower
  • A lower ISO means your image will appear darker so your shutter speed needs to be slower and your aperture wider
  • A wider aperture means more light is able to reach your camera’s sensor, so you can have a faster shutter speed and lower ISO
  • A narrower aperture means less light is able to reach your camera’s sensor, so you will need a slower shutter speed and possibly a higher ISO

When you change one of these settings, it affects the rest of them as well. If you’re shooting in full manual mode, you have to adjust all three according to what the exposure calls for. However, when shooting in aperture priority mode, the camera will adjust the other two for the situation.

A quick tip: Make sure your ISO is not set to AUTO. Higher ISOs tend to make for grainy photos. So, to avoid this select your own ISO and if needed adjust based on the lighting situation. I usually set mine between 200 and 400 and try not to go over 1000 unless I have to.

Aperture and Depth of Field

1/320 sec at f2.8 ISO 400

Being able to control your aperture is a really good way to control the amount of light that hits your camera’s sensor and to control your overall exposure. But aperture is also responsible for something else that’s pretty cool: depth of field.

What is depth of field? It’s the amount of your image that’s in focus. There’s a bit of physics involved but adjusting your aperture determines how much of the image remains in focus. Smaller apertures (bigger f-stop numbers) mean that more of the image is in focus while larger apertures (smaller f-stop numbers) mean that less of the image is in focus. So if you’re wanting a blurry background with just your subject in focus you would want an aperture of f/2.8 over something like f/11. But if you’re shooting a landscape shooting at f/11 would be more ideal.

What is the Right Aperture?

Choosing the right aperture depends on several different factors. In my experience as a mostly aperture priority mode shooter, subject matter is the most important thing to consider. I love to get up close and personal with plants and flowers, but I also shoot houses for a living. Two totally different things with two totally different methods for shooting. Which means two completely different apertures.

Here’s a bit of a guide if you’re having trouble deciding:


These apertures are some of my favorites to work with. For many fixed lenses f/1.8 is widest aperture they allow, while for many zoom lenses f/2.8 is the widest they go. These apertures have the largest opening which means they let the most light in. They also have the shallowest depth of field. f/1.8 and f/2.8 are awesome for close-up subjects with blurred background and foreground. I frequently use f/1.8 for shooting plants and flowers and f/2.8 for the few portraits I do.

f/4 and f/5.6

For many kit lenses f/4 and f/5.6 are the widest apertures offered. If you’re lens shopping, you’ll also notice that there are sometimes two versions of a lens, or two very similar lenses. One of these will usually have the widest aperture as f/4 or f/5.6 and one (usually more expensive) will have the widest aperture of f/2.8 or something similar. While I prefer to shoot with wider apertures, f/4 and f/5.6 are still great for getting your subject in focus while having blurred backgrounds and foregrounds. I actually still use f/4 on one of my kit lenses if I ever need something with more zoom.


There’s a saying that goes “f/8 and be there” which basically means be present and take the opportunity to get the photo as opposed to worrying about the technical side. f/8 is a great happy medium for many lenses and many photographers use it on a wide variety of subjects. In daylight and even cloudy situations f/8 allows enough light to enter the camera to avoid camera shake. It also still has a shallow enough depth of field to get some background blur to help isolate your subject. This aperture is a great starting place if you’re still trying to get a feel for how aperture relates to shutter speed and depth field, and how it affects your image overall.


I use this aperture daily for my real estate work. I also use it for most of my landscape shots. f/11 is great for daytime handheld shots where you want foreground and background in focus. It also does great in darker situations if you have your camera on a tripod.


At f/16 a lot less light is entering your camera which means your shutter speed needs to be slower or your ISO needs to be higher. An aperture of f/16 allows for pretty much your whole frame to be in focus (stuff that’s super close to the lens will probably not be). However, the possibility of camera shake becomes much more likely at this aperture. f/16 is great for getting super sharp shots of landscapes, cityscapes and architecture, but it’s best to use a tripod if possible at this aperture.


For most consumer lenses f/22 is the narrowest the aperture can go. That means the the little hole in your lens is letting in very little light and requires a much slower shutter speed. As someone who shoots primarily in aperture priority mode, I only use f/22 when I want a super slow shutter speed. And that is usually when I’m shooting a waterfall. f/22 is great for landscapes and will allow for pretty much everything in your frame to be in focus. However, it’s almost guaranteed that you will need a tripod at f/22.

Keep in mind that these aren’t the only apertures. Your camera and lens will have many more available to use between your widest and narrowest apertures. These are just some of the more common ones and some of the ones I find myself using most frequently.

Distance Matters

So if it’s not obvious already, there is quite a bit of math and physics involved in photography. I did alright in these subjects in school and then promptly forgot them, thinking they would never be relevant. They are, a bit. However, that doesn’t mean you have to make difficult calculations every time you pull your camera out. You just have to do a bit of trial and error.

When it comes to choosing an aperture, distance does matter a bit. You’ll notice this most when shooting in wider apertures. Your subject will be in focus but if you’re too close to your background, your background will also be in focus. This is fine if that’s what you’re going for, but if you want the background blurred, you have to pull your subject away from it.

Shooting in Aperture Priority Mode

Shooting in aperture priority mode allows you to focus on just the aperture setting without having to worry about shutter speed, too. Aperture priority mode can give you a lot of freedom and ability to create the shots you want. Whether you’re shooting sweeping landscapes or up-close and personal portraits, understanding and being able to control your aperture is super important. And shooting in this mode will allow you to do just that.

If you’re new to photography, shooting in aperture priority mode is also a great way to start getting out of auto mode. If you’re goal is to eventually shoot in full manual, start playing around in aperture priority mode and see how the camera selects the shutter speed for certain situations.

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Hey there! My name is Leah and I'm a photographer, blogger and wanderer from north Texas. I've been doing photography for nearly a decade now and absolutely love it. My day job is real estate photographer and in my free time you can often find me at a park taking pictures of leaves and flowers. Outside of that my fiance and I love to travel. We spent nine months backpacking through Europe and now spend our free time attempting to plan and going on shorter trips both in the States and abroad.


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