Photo Tip Friday: Understanding Aperture, Part 1

by Mary Denman   @MaryDenman

Understanding Aperture by Mary Denman Photography
Today’s photography tip is to learn about aperture. It’s a function on your camera that may seem intimidating at first.

Aperture controls the size of the shutter opening. That’s simple enough. But the challenge comes with understanding that the size of the shutter opening has two functions.  

The size determines: 
1) how much light can be let in 
2) how deep the depth of field is. 

We are going to cover just one aspect this week and one next week. That should help make it easier to understand and remember how aperture works in photography.

So, let’s get started and learn about how the size of the shutter opening (aperture) affects how much light is let into the camera. 

First though, you have to know how or where to control aperture on your camera. You can use either Av (aperture mode) or M (manual mode), as noted in COLLAGE 1. When you look at the info before you take a shot, you can highlight and change your aperture while in either of these modes. 

COLLAGE 1: How to control aperture on your camera by Mary Denman Photography

TIP 1: Get your camera out and see if you have either an Av mode or an M mode. Then set your camera on one of them and TRY a few shots right where you are to see what happens. This will help you understand the rest of the post more.

Now let's see a visual of what the shutter opening inside your camera looks like in COLLAGE 2.

COLLAGE 2: Aperture opening size chart from

COLLAGE 2: Aperture is the size of the shutter opening. As you can see, f/32 is the smallest opening and lets in the least amount of light. Conversely, f/1.4 is the widest opening and lets the most light in. 

TIP 2: Remember the two extremes on the chart: 
F/32 lets in the LEAST amount of light.
F/1.4 lets in the MOST light. 

That's a quick way to learn the principle. In the field, knowing the extremes can help you choose which end of the scale to use! 

Let's put that to the test in the pictures below

COLLAGE 3: ISO 400, Tv 1/10 sec, Av changes in each Mary Denman Photography
COLLAGE 3: In this series of photos, I maintained the same ISO of 400 and the same TIME of 1/10th of a second. The only thing that changes is the aperture. 

I set up the first photo of this cute shed so that the aperture of f/22 gave me a shot that had proper lighting. 

Because f/22 has such a small opening, notice that the ISO is set at 400 which needs less light. But even so, I had to set the time fairly slow to allow enough light in to get a well exposed photo. 1/10 of a second is too slow to hand hold and get a clear shot. The reason the shots are in focus is because I used a tripod for my examples. 

But watch what happens when I started to use other apertures. f/16 is a little washed out since it lets in more light. f/8 is overexposed and f/4 is almost entirely overexposed to the point of being white. 

Why? Because the size of the shutter opening (or aperture) greatly affects the amount of light being let in. 

So, what happens if I set a shot up to be at proper exposure with an aperture of f/4? Let's see in the next series.

COLLAGE 4: ISO 100, Tv 1/200 sec, Av changes in each Mary Denman Photography
COLLAGE 4: The ISO of 100 and Tv of 1/200 of a second shutter speed is maintained in the four shots. The variable that changes is the aperture. 

Again, I set this shot up to have a proper exposure at an aperture of f/4. 

To keep the picture from being overexposed, I had to use ISO of 100 since it needs a lot of light. The shutter speed was fast at 1/200 of a second to get the right exposure. 

But look what happens in the shot with an aperture of f/8. The shot is underexposed. f/16 and f/22 are almost unrecognizable from all of the black. 

So what can we learn this week?

TIP 3: When you use an aperture of f/32 that lets in less light, you'll probably need to use a longer time exposure and a higher ISO that needs less light to get a proper exposure. 

TIP 4: When you use an aperture of f/1.4 that lets in lots of light, you'll probably need to use a faster time exposure and a lower ISO that needs more light to get a proper exposure. 

But why do we need to learn this at all? 

Because we need to understand both parts of what aperture controls. 

While this week's post is a bit more technical, next week's post will show you how depth of field is controlled and that can produce some pretty dramatic results in your photo taking skills. It'll be worth it, I promise!!

So, get your camera out and EXPERIMENT with the Av or Manual setting. Take a few shots that are under or over exposed. Better to do it at home when it doesn't matter than when you really need the shots to count! 

For BLOGGERS: As you practice photography, you'll feel more comfortable using your own images for your blog. This is great for a couple of reasons. 

1) Your own photography can help you with the creative side of your blog. Think content! Either your photos can inspire or illustrate your posts. Both are valuable. 

2) Your photography can help you avoid copyright infringements. This is real and can be a huge deal. Just because you see an image on the internet does not make it free! By using your own pictures, you can avoid this all together. 

Hope these tips help!

Keep on clicking! 


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  1. Great tips Mary :)

    Thanks for hopping by the weekend blog hop, have a lovely weekend..

    1. Thanks Claire! I'm having my son's birthday party this weekend, so it will be lively for sure! You have a good weekend too!

  2. Gee, I always thought aperture was the opposite of overture. :) Just had to be silly!
    I'm going to have to dig out my husband's old Olympus camera - my cell phone won't do these cool things.

    1. Ha ha ha ha!!

      Definitely go find the other camera! It will teach you a lot!!

  3. Hmmm,..I really need to learn to use my camera. There's just so much to remember when you want to catch a shot quickly that I miss the moment which I why I stick with my iPhone. Hope you had a great weekend..thanks for linking up with my party :)

  4. Really helpful for someone like me!