Understanding Aperture (a.k.a How To Make Your Background Blurry)

One mode I use a ton in food photography is the aperture priority mode, often labeled as Av Mode. Aperture is the reason your background is or isn’t in focus. If used properly, it makes a huge difference because it gives your viewers a focus point. It was also one of the hardest concepts for me to grasp because everything I read was really technical. The Internet needs a non-techie guide, so here I am bringing that to you.

However, there will be *some* technical explanation. Before I scare you off, this is what you need to know: the smaller your f number, the blurrier your background. In other words, if you want to focus on the object in front and blur out the background, use a low f number (very common in food photography). If you want everything to be in focused including the background, use a high f number (very common in landscape photography).

Cinnamon Pecan Cherry Pie – Aperture: f 2.8

What is aperture? The aperture of a camera is the opening in the lens which light travels through. Controlling the size of the aperture controls the amount of light traveling through. You control the size using what your camera refers to as f-stops or f-numbers, which is the letter f followed by a number (f 1.8, f 3.5, f 9.0). The smaller the number, the wider the opening. The wider the opening, the more light travels through (think of it like opening your curtains in the morning – the more you pull back, the more light shining through).

Did you glaze over that last paragraph? It took me years to understand that, mainly because everything I read was too technical. Here, I’ll translate that for you: the smaller your f number, the blurrier your background. You want those cups in the background to be blurry? Low f-number. You want the basket of lemons to have shape but not in focus? Middle f-number. You want me to see your entire ice cream sundae table set-up? High f-number.

Double Lemon Glazed Doughnuts – Aperture: f 6.3

Bacon and Dried Cherry Chocolate Chip Cookie – Aperture: f 5.6

Why should I care about whether my background is in focus? The simple answer is depth of field, which is the distance between the foreground and background of your scene. This means you have something in the front and something in the back. Sometimes it’s really obvious, such as a cup of coffee behind some donuts. Other times it may not be so clear, such as a single cookie on a plate.

Grand Canyon – Aperture: f 13 (even though the f-number is high, distance between the foreground and background plus high mid-day sun still created some blur)

Depth of field is important because it adds dimension. Distance is the biggest challenge when photographing. When I visited the Grand Canyon, my biggest challenge was portraying how huge and deep it was. The only way I could really accomplish this is to layer my photograph and have a prominent foreground and background. Sometimes I would even have a midground, which is the layer between your foreground and background. My favorite part of adding dimension is using clouds. Clouds add so much more depth, it’s crazy. A beautiful cloudy day is the best picture-taking weather.

Understanding Aperture (a.k.a. How To Make Your Background Blurry)
Statue of Liberty – taken on my iPhone (aperture unknown, but look at the clouds!)

Easy Chocolate Peanut Butter Fudge – Aperture: f 3.2

Another reason to care about your background is to give your viewers a focus point. Sometimes you want objects in the background to emphasize what your photo is about, such as strawberries for strawberry cupcake. However, you want your focus to be on the cupcake, not the strawberries. Other times you may find yourself in a situation where the background is distracting, but you have no control over fixing it. Blurring will help tone that down.

Strawberry Shortcake Cupcake – Aperture: 5.6

How do I adjust the f number? The best way is to refer to your camera’s manual. For my Canon Rebel, I turn a knobbed wheel. If I’m using complete manual mode, I have to hit another button (for me it’s marked Av) before turning the wheel.

Understanding Aperture (a.k.a. How To Make Your Background Blurry)
Murray – Aperture: f 1.8

Why can’t I go below a certain f number? F number is actually based on your camera lens, not your camera itself. The number is listed on the lens spec. For example, I have the 50 mm f 1.8 lens. The lowest I can make my f number is 1.8. There is no zoom range, so I can make it f 1.8 no matter where I stand. If I had gotten the 50 mm f 1.4, the lowest would be 1.4. When I use my 28-135 mm f 3.5-5.6 lens, the lowest I can go is f 3.5 when I’m at 28 mm and f 5.6 when I’m at 135 mm. In this case, the lowest the f number can go is dependent on the zoom range.

Sweet Chili Sauce – Aperture: f 3.5

Here’s an exercise I did for you with my Peanut Butter-Stuffed Chocolate Cookies. I placed the camera on a tripod and left all of the settings the same except for the f number. You can see as the f number gets higher, the background becomes more focused. Which one looks best to you? There is no right or wrong answer. My personal preference is around f 2.5 – f 4.0. I don’t like my background super duper blurry, so I rarely use f 1.8. However, I don’t like the mid range too much because then it looks like I simply couldn’t focus rather than purposely blurring the background.

Understanding Aperture (a.k.a How To Make Your Background Blurry)
Aperture: f 1.8

Understanding Aperture (a.k.a How To Make Your Background Blurry)
Aperture: f 2.5
Understanding Aperture (a.k.a. How To Make Your Background Blurry)
Aperture: 4.0
Understanding Aperture (a.k.a How To Make Your Background Blurry)
Aperture: f 5.6

Understanding Aperture (a.k.a How To Make Your Background Blurry)
Aperture: f 8.0

Understanding Aperture (a.k.a How To Make Your Background Blurry)
Aperture: f 10

I put my f number pretty high and it’s still blurry. Why? In addition to f number, your photograph could be blurry for several other reasons. The main two are lighting and movement. Aperture is connected to shutter speed. Both are dependent on light. If you have low lighting, the shutter speed is slower. Slower means you have to hold it still longer. No matter how careful you are, it’s very difficult to not get camera movement when at a slow shutter speed.

The best solution is a tripod. Spend the extra money and buy a really great one. I am borrowing one at the moment that has a not-so-sturdy lock on the one leg. It also doesn’t have a bubble level. It is so frustrating to use it, but right now that’s all I got.

Vegan Peach Curd – Aperture: f 2.8

If you feel like you’re not getting enough blur, try putting more distance between your subjects.

Root Beer Float Cupcakes – Aperture: f 2.5

I hope I was able to explain aperture on a non-techie level. Even if you don’t understand most of what I said, just remember that the smaller your f number, the blurrier the background. Next time you’re shooting, play in Av mode and take shots with different f numbers. See which ones work the best for your style. Know which ones you aren’t crazy about.

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