Aperture is one of the three fundamental camera settings, alongside shutter speed and ISO, and it’s arguably the most important. It affects not just how bright your image is, but also how much of it is in focus and how sharp it looks. Understanding aperture changes the way you photograph.
In this guide, I’ll explain what aperture is, how it works, and how to use it to take better photos. You’ll learn what f-stops actually mean, how aperture controls depth of field and sharpness, and which aperture values to use for different situations, including specific guidance for landscape photography.
If you want to understand how aperture fits into the bigger picture alongside shutter speed and ISO, the Exposure Triangle is a good place to start.
- What is Aperture in Photography?
- What is an F-Stop
- Aperture and Depth of Field
- Aperture and Exposure
- Aperture and Sharpness
- Best Aperture Settings for Different Situations
- Aperture for Landscape Photography
- Which Camera Mode Should You Use?
- Conclusion
What is Aperture in Photography?
Simply put, aperture refers to the opening inside your lens through which light passes to reach the camera sensor. The size of that opening is adjustable, and changing it affects three things at once: how much light reaches the sensor, how much of your image is in focus, and how sharp the image is.
Think of it like the pupil of an eye. In bright conditions, the pupil contracts to limit the amount of light that enters. In the dark, it widens. Your lens works the same way, and just like the eye, the size of the opening has consequences beyond just brightness.
That last point is what makes aperture genuinely interesting. Shutter speed and ISO are primarily exposure controls. Aperture is an exposure control and a creative tool at the same time, which is why it takes a little longer to fully understand, but it rewards the effort.
What is F-Stop?
Aperture is measured in f-stops, written as f/2.8, f/8, f/11, and so on. The number represents the ratio between the focal length of the lens and the diameter of the opening, which is why the scale feels counterintuitive at first: a lower f-number means a larger opening, and a higher f-number means a smaller one.
So f/2.8 is a wide aperture that lets in a lot of light. f/16 is a narrow aperture that lets in much less. If you can keep that relationship in mind, everything else about aperture starts to make sense.
One stop represents a doubling or halving of the light reaching the sensor. Going from f/8 to f/5.6 doubles the light. Going from f/8 to f/11 halves it. This matters when you’re balancing exposure, because changing the aperture by one stop requires a compensating change in shutter speed or ISO to maintain the same brightness.
If the numbers printed on your lens look like f/2.8 or f/4-5.6, that’s the widest aperture available on that lens, which sets the upper limit of how much light it can gather.
Aperture and Depth of Field
Depth of field is the most important and most creative aspect of aperture. It refers to how much of your image is in sharp focus, from foreground to background.
This is where aperture becomes a genuine creative decision rather than just a technical one.
Choosing how much of your scene to keep sharp is as much a compositional decision as a technical one. For a deeper look at how to build stronger images from the ground up, the composition guide is worth reading alongside this one.
Shallow Depth of Field
A wide aperture, such as f/2.8, produces a shallow depth of field, meaning only a narrow plane of the image is in sharp focus while everything in front of and behind it blurs. The image below shows a typical example: the flowers are sharp while the background dissolves into softness.
A shallow depth of field is most commonly associated with portrait photography, where blurring the background isolates the subject. It’s also essential for night photography, where a wide aperture is needed to gather enough light.
Recommended Reading: When to Use an Open Aperture in Landscape Photography
Large Depth of Field
A narrow aperture, such as f/16, has the opposite effect, keeping more of the image sharp from front to back. This is the approach most landscape photographers use for the majority of their work; you want the foreground rocks as sharp as the distant mountains.
However, a narrow aperture doesn’t automatically mean everything is sharp. If your composition includes elements both very close to the lens and very far away, even f/16 may not give you front-to-back sharpness in a single frame. This is where focus stacking comes in; by taking multiple exposures focused at different distances and blending them in post-processing, you can achieve sharpness across the entire scene without having to push your aperture to values that compromise image quality. I use this approach regularly in my own landscape work.
Recommended Reading: The Ultimate Focus Stacking Guide for Landscape Photography
Aperture and the Exposure
The second thing aperture controls is exposure, meaning how bright or dark your image is.
A wide aperture lets more light reach the sensor, producing a brighter image. A narrow aperture restricts the light, producing a darker one. The experiment below illustrates this clearly: the same scene photographed at f/4, f/10, and f/22, with shutter speed kept constant throughout.
In practice, aperture is rarely your primary tool for controlling exposure. Shutter speed handles that in most situations, because it doesn’t carry the depth of field and sharpness trade-offs that aperture does. But understanding how aperture contributes to exposure is important, especially when working in Manual Mode and balancing all three settings together.
If you want to understand the full relationship between aperture, shutter speed, and ISO, the Exposure Triangle covers this in detail.
Aperture and Sharpness
The third thing aperture affects is sharpness, and this is the part that trips most people up.
You might assume that using the narrowest aperture gives you the sharpest image. It doesn’t. Every lens has a sweet spot, typically around two to three stops from its widest aperture, where it produces the sharpest results. Beyond that, a phenomenon called diffraction starts to soften the image, and the more you stop down, the worse it gets.
Here’s a practical reference for finding your lens’s sharpest aperture:
| Widest Aperture of the Lens | Sharpest Aperture Range | |
| f/2.8 | f/5.6 to f/8 | |
| f/4 | f/8 to f/11 | |
| f/5.6 | f/11 |
Note that these are guidelines rather than absolutes; the exact sweet spot varies slightly by lens and manufacturer. The best way to find yours is to photograph a static subject at every aperture your lens offers and compare the results at 100%.
What this means in practice: avoid f/16 and beyond whenever possible. The depth of field gain is marginal compared to what you get at f/11, and the sharpness loss is real. There are rare exceptions, which I’ll cover below.
Best Aperture Settings for Different Situations
There’s no single correct aperture for every situation. The right choice depends on what you’re shooting, what depth of field you want, and how much light is available. Here are the guidelines I’d suggest as a starting point:
Landscape photography (general): f/8 to f/11. This range gives you a strong depth of field across most scenes while keeping you within the sharpest part of your lens’s performance. It’s where I spend the vast majority of my time.
Night photography and astrophotography: f/2.8 to f/4. You need to gather as much light as possible with a quick enough shutter speed to avoid star trails. A wide aperture is non-negotiable here.
Images where you want background blur: f/2.8 or wider. Whether you’re isolating a flower in the foreground or shooting a portrait, a wide aperture separates the subject from the background.
Macro photography: f/5.6 to f/8. Depth of field is extremely shallow at close focusing distances, so a moderately narrow aperture helps, though focus stacking is often needed for complete sharpness.
When you absolutely must slow the shutter speed: f/16 to f/22. I’ll occasionally stop down this far if I need a slower shutter speed and don’t have an ND filter to hand. The sharpness cost is real, so whenever possible, I’ll take a second shot at f/11 and blend the exposures in post. But sometimes you work with what you have.
These are starting points, not rules. Every scene is different, and experience will teach you when to deviate.
Aperture for Landscape Photography
Since this is a landscape photography site, it’s worth being specific about how I approach aperture in the field.
For the vast majority of my landscape work, I shoot between f/8 and f/11. This gives me a strong depth of field across the scene, keeps me within the sharpest aperture range for my lenses, and works with the exposure I’m typically looking for on a tripod at base ISO.
When f/11 isn’t enough to achieve front-to-back sharpness, usually because I have a strong foreground element very close to the lens, I focus stack rather than stopping down further. A blend of two or three exposures focused at different distances will always outperform a single image at f/22 in terms of overall image quality.
The one scenario where I’ll push to f/22 is when I need a slower shutter speed and don’t have an ND filter available. In those cases, I try to take a second shot at f/11 and merge the two. But it’s a genuinely rare situation.
For more detail on choosing the right aperture for landscapes specifically, including how focal length and subject distance affect your depth of field, take a look at The Best Aperture for Landscape Photography.
If you’re looking to build a more complete foundation for landscape photography beyond camera settings, the landscape photography guide covers everything from gear and planning to technique and post-processing.
Which Camera Mode Should You Use?
Understanding aperture is one thing; knowing which camera mode to use to control it is another.
Manual Mode gives you full control over aperture, shutter speed, and ISO independently. This is the mode I use for almost all of my landscape work. It takes practice to develop the instinct for balancing the three settings, but once it becomes natural, you’ll wonder how you ever worked any other way.
Aperture Priority Mode (Av on Canon, A on Nikon and Sony) lets you set the aperture while the camera automatically adjusts the shutter speed for correct exposure. This is the best semi-automatic option for photographers who aren’t yet comfortable with full manual control. You still make the creative depth-of-field decision while the camera handles the exposure calculation. Use exposure compensation to adjust the brightness if the camera’s choice isn’t quite right.
For landscape photography specifically, Manual Mode is worth working towards. Light changes quickly in the field, and being able to adjust all three settings independently without the camera second-guessing you is a real advantage.
Conclusion
Aperture is the camera setting with the most creative impact. It controls depth of field, contributes to exposure, and determines how sharp your image will be; and those three things interact with each other in ways that take time to fully understand.
The practical takeaway for landscape photography is straightforward: f/8 to f/11 handles the majority of situations, focus stacking solves the cases it doesn’t, and anything beyond f/16 should be a last resort rather than a default.
The best way to internalize aperture isn’t to memorize the rules; it’s to go out and experiment. Set your camera to Aperture Priority, shoot the same scene at f/2.8, f/8, and f/16, and compare the results. That direct experience will teach you more than any guide can.
For a deeper understanding of how aperture works alongside shutter speed and ISO, see the Exposure Triangle. And if you’re working on building a consistent landscape photography workflow from the ground up, the post-processing guide is a good next step.
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This article is part of a series on the fundamental camera settings. You can find the other parts here:
- Part 1: The Exposure Triangle
- Part 2: Introduction to Shutter Speed
- Part 3: Aperture in Photography (you are here)
- Part 4: ISO in Photography
