Ever wondered how professional photographers get those beautifully blurred backgrounds in their portraits? Or how they manage to keep an entire sweeping landscape perfectly sharp from front to back?
It all comes down to one fundamental camera setting.
In this guide, I will explain exactly what aperture is and how you can use it to improve your photography.
At its core, aperture is simply the opening in a lens through which light enters the camera.
Think of it like the pupil of your eye. When you move into a dark room, your pupil dilates to let more light in. When you step outside into bright sunlight, your pupil constricts to block out the light. Your camera lens does the exact same thing.
Together with shutter speed and ISO, it forms the exposure triangle. These three pillars work together to determine how bright or dark your photo will be.
How aperture works: the technical basics
Inside your camera lens, there is a set of mechanical blades. These blades physically open and close to adjust the size of the hole that lets light reach your camera sensor.
We measure the size of this opening using f-stops. You have probably seen these numbers on your camera screen before, like f/1.4, f/2.8, f/5.6, or f/16.
This is where almost every beginner gets confused. It feels incredibly counterintuitive when you first pick up a camera to learn that a smaller number means a bigger hole.
But there is a logical reason why it works this way. The f-number is actually a fraction.
Think of it like slicing a pizza. If you are offered 1/2 of a pizza, you are getting a massive amount of food. If you are offered 1/16 of a pizza, you only get a tiny sliver.
The exact same logic applies to your camera lens. An aperture of f/2 (think 1/2) is a huge opening. An aperture of f/16 (think 1/16) is a tiny opening.
Let us make this even more practical with a real-world scenario.
Imagine you are taking photos in a dimly lit living room. If you set your lens to a small f-number like f/1.8, it is like throwing open the curtains on a giant bay window. It lets an enormous amount of light flood into the camera, allowing you to capture a bright photo in a dark space.
Now imagine you are at the beach at noon on a bright summer day. Setting your camera to a large f-number like f/16 is like looking through a tiny peephole in a door. It restricts the intense sunlight so your photo does not turn out completely white and ruined.
Understanding stops of light
As you learn about aperture, you will often hear photographers talk about changing their settings by a “stop” of light.
The standard scale of full aperture stops looks like this: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16.
When you change your setting by one full stop on this scale, you are either halving or doubling the exact amount of light that hits your camera sensor.
For example, imagine you are photographing a friend inside a cozy cafe. You take a test photo at f/4, but the image looks too dark on your camera screen. If you change your aperture to f/2.8, you are moving one full stop down the scale. By doing this, you literally double the amount of light entering the lens. Your image instantly becomes twice as bright.
Conversely, if you are outside and your photo at f/5.6 is too bright, changing your aperture to f/8 halves the amount of light entering the lens.
It takes a little bit of practice, but once you realize you are just doubling or halving the light with each click of your camera dial, you gain complete control over your exposure.
Aperture and light
The most obvious function of the aperture is controlling the exposure of your image.
Shooting wide open with a low f-number, such as f/1.8 or f/2.8, is ideal for low-light situations. Whether you are shooting indoors, at night, or doing astrophotography, a wide opening lets in a ton of light. This also allows you to use faster shutter speeds to freeze motion in the dark.
Shooting stopped down with a high f-number, like f/11 or f/16, is what you need for very bright situations. On a sunny day or in the snowy mountains, a small opening restricts the light. This helps prevent your photos from being overly bright or washed out.
Aperture and depth of field
While controlling light is an essential technical skill, depth of field is where the real creative magic happens. This is the setting that allows you to direct the viewer’s eye exactly where you want it to go.
But what exactly is depth of field?
Simply put, depth of field is the zone of acceptable sharpness in your photo. It is the distance between the closest object and the farthest object in your scene that both appear sharp.
Depending on your aperture, this zone of focus can be practically paper-thin or stretch for miles.
Shallow depth of field: the power of blur
A shallow depth of field happens when you use a low f-number like f/1.4, f/1.8, or f/2.8. With these settings, your lens is wide open, which creates a very narrow slice of focus.
If you focus on your subject’s eye, it will be perfectly sharp, but the background will be completely out of focus.
This is highly desirable when you want to eliminate distractions. Here are a few practical examples of when to use it:
- Portrait photography: Imagine you are shooting a portrait of a friend on a busy shopping street. If you use a wide aperture like f/1.8, your friend’s face will be tack sharp, but the chaotic crowds and bright store signs behind them will melt away into a soft blur. You instantly isolate your subject and make them the undeniable star of the photo.
- Macro photography: If you are photographing a single raindrop on a leaf, a wide aperture helps blur the messy branches behind it. It draws the viewer’s attention purely to the tiny details of the water drop.
This out-of-focus background blur is often called bokeh. Bokeh describes the aesthetic quality and feel of the blur. Fast lenses with multiple aperture blades produce beautiful, creamy bokeh that gives portraits a very premium, professional look.
Deep depth of field: capturing the whole story
A deep depth of field is the exact opposite. This happens when you use a high f-number, such as f/8, f/11, or f/16. Because the opening in your lens is now tiny, the physics of light changes, creating a massive zone of focus. Everything from the immediate foreground to the distant horizon will appear perfectly sharp.
Here are a few scenarios where a deep depth of field is crucial:
- Landscape photography: You are standing on a beach at sunset. You want the textured rocks just a few feet in front of you to be just as crisp and detailed as the mountains miles away in the background. Stopping your lens down to f/11 or f/16 guarantees that the entire sweeping scene is in focus.
- Large group photos: If you are photographing a corporate event with three rows of people, shooting at f/1.8 would be a disaster. The front row would be sharp, but the people in the back row would be blurry. Setting your aperture to f/8 ensures everyone in the group is sharp and recognizable.
- Street photography: When I am doing street photography, I often want to show the environment. I want my main subject to be sharp, but I also want the city’s architecture behind them to be recognizable, giving the photo context and a sense of place. Shooting around f/8 is usually perfect for this.
By mastering these two extremes, you gain absolute control over the story your photo tells. You can choose to isolate a single beautiful detail or showcase the entire world around it.
Advanced aperture concepts
Once you master the basics, you can start looking at your camera gear a little differently. Breaking down the technical jargon will help you make better choices when buying or using lenses.
Lens speed
You will often hear photographers talk about “fast” lenses. A fast lens is simply a lens with a very wide maximum aperture, like f/1.4 or f/1.8. Because the opening is so large, it lets light hit the sensor much faster, allowing for quicker shutter speeds. Prime lenses (lenses with a fixed focal length) usually have wider maximum apertures than zoom lenses.
Variable vs. constant aperture
Have you ever noticed your entry-level kit lens getting darker when you zoom in? That is because it has a variable aperture. For example, the maximum opening might be f/3.5 when zoomed out, but it shrinks to f/5.6 when you zoom in on a subject.
Professional zoom lenses are heavier and more expensive because they maintain a constant aperture, meaning a lens like a 24-70mm f/2.8 will stay at exactly f/2.8 no matter how far you zoom.
The sweet spot for sharpness
Shooting at your lens’s absolute widest setting or its narrowest setting often results in slightly softer images. To get the maximum crispness out of your gear, you need to find its sweet spot. Most lenses are sharpest right in the middle of their aperture range, usually around f/5.6 to f/8.
Diffraction
If you push your f-number too high to something like f/22, you run into diffraction. This is an optical physics issue where squeezing light through a tiny hole causes the light waves to scatter. This actually causes the image to lose overall sharpness and look slightly blurry.
Creating sunstars
Despite the risk of diffraction, tiny openings are not entirely bad and can be used to create creative effects. If you use a small aperture, such as f/16, you can create sunstars in your images. The small opening forces the light to bend around the aperture blades, turning bright, focused light sources like the afternoon sun or streetlights at night into beautiful starbursts.
Practical application: how to use aperture today
Knowing the theory is great, but you need to put it into practice.
I highly recommend trying aperture priority mode. You will find it as an A or Av on your camera dial. This is the favorite shooting mode for many professional photographers, including myself.
In this mode, you choose the aperture to control your depth of field. The camera then automatically calculates the right shutter speed to give you a perfect exposure.
Here is a simple homework assignment to try today.
Put an object on a table. A coffee mug works perfectly. Stand a few feet away with your camera.
Take one photo at your lowest f-number, like f/4. Then change it to f/8 and take another. Finally, take a third photo at f/16. Look back at the images and compare the backgrounds. You will instantly see how much creative control you have just gained.
Conclusion
To summarize, always remember the golden rule. A low f-number gives you a blurry background and lets in more light. A high f-number gives you a sharp background and lets in less light.
Understanding how to control this setting unlocks so much creative potential. It takes you out of auto mode and puts you in the driver’s seat of your photography.
What are you planning to photograph first using your new knowledge? Get your camera, step outside, and start shooting those frames!
One thought on “What is Aperture? The ultimate guide for beginners”