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The Complete Beginner’s Guide to Aperture

The aperture is part of the holy trinity of photography settings, along with ISO and shutter speed. Knowing what aperture does and how it impacts your photo is valuable in creating the desired visual effect. By the end of this article, you’ll understand the fundamentals and effects of aperture on your photos.

Introduction to Aperture

Have you ever noticed how pupils work in the dark and in overly lit areas? When it’s dark, the pupils dilate (open wide) to let in more light. When it’s too bright, the pupils become smaller to let in less light and protect your eyes.

The eye is similar to how the aperture in lenses works. The aperture is the lens opening where light passes through to get to the sensor or film. If the eye is the lens, the pupils are the aperture. When the aperture closes into a smaller hole, less light gets into the camera; when it opens, more light enters.

You can look at your lens, but here’s an image to show what the aperture looks like:


Behind the lens, there are “aperture blades” that close and open into a hole to allow less or more light to pass through the lens. Note that the blades form a hole with edges. The aperture shape can change depending on how many blades there are and how wide open is the aperture.

When I didn’t know much about photography, one of the first things I wanted to know was how to make the background extremely blurry to get that beautiful separation effect (which I discovered was called “bokeh”). You probably have that question on your mind, too. Well, the aperture settings did the trick.

Aperture provides depth in your photo by widening or narrowing the “depth of field.” By changing the depth of field, the focus gets more or less shallow, resulting in a background that is either blurry or more in focus. If you want to isolate or separate your subject from the background and foreground elements, having a very wide aperture will give you that effect since the depth of field becomes shallower.

Aperture also controls how much light gets in to affect the exposure of the image. Without altering the ISO and shutter speed, a wider aperture lets in more light, resulting in a brighter photo. A narrower aperture lets in less light, leading to a darker photo.

For a quick rundown on how aperture affects your photo output, refer to this list:

  • Exposure and brightness
  • Depth of field
  • Out of focus quality/bokeh
  • Gain and loss of sharpness
  • Diffraction
  • Starburst and sunstar effects
  • Focusing ability under low light conditions
  • Focus shift
  • Flash exposure
  • Appearance of dust specks on camera sensor

I’ll be discussing these more in-depth throughout the article, so keep on reading to learn more.


We can’t just keep referring to aperture as wide or narrow, large or small, can we? That doesn’t make for precise measurements. If someone asks you what aperture you used, saying something like “very large” will make for a confusing answer. And in fact, the size of the aperture hole corresponds to specific numbers called the “f-stop” or “f-number.”


This Sony camera has an aperture setting of f/2.8. It’s shown on the LCD screen, and it can be adjusted by turning the aperture dial.

You’ll see in the lens description or in-camera settings that there’s an “f” followed by a number—that’s the aperture. It could be written with or without a slash before the number—e.g., f/4 or f4. Adjusting the settings yields a higher or lower number, like f/2.8 to f/16. If someone asks you what aperture setting you used, just refer to the f-stop.

How to Set Aperture

Now that we can refer to the aperture value appropriately, how do we make it go up or down?

In analog or vintage lenses, changing the aperture is done by moving the “aperture ring” (not the “focus ring”) on the lens itself. If you manually turn the ring clockwise or counter-clockwise, the aperture blades contract or expand accordingly. If you have a lens that does this, it’s a pretty great tactile experience.

Nowadays, modern lenses have electronic components that communicate with the camera and allow you to electronically change the aperture. Gone is the manual labor of turning the ring; now all you have to do is turn a small dial left and right, or press some buttons to go up or down.


In a camera, turning the mode dial to M or A allows you to change the aperture manually.

Your camera should be in a mode that allows you to change the aperture manually. It can be in the manual mode (“M” in most cameras), where you’ll have to set the shutter and ISO manually. Or you can use aperture-priority mode (“Av” or “A”) so that the shutter and ISO automatically change depending on your aperture and exposure settings.

Aperture Size and F-stop

Naturally, a higher f-stop means a larger aperture size, and a lower f-stop means a smaller aperture size, right? Not quite. It’s the other way around.

A higher f-stop means a smaller aperture size, and a lower f-stop means a larger aperture size. For a complete beginner, there will be some initial confusion, but it’s a simple matter of reversing your conventional thinking. You simply need to understand that a low f-number = large aperture, high f-number = small aperture. Don’t worry. Like me, you’ll quickly get used to it.

The reason it’s reversed is relatively simple: aperture is measured in terms of fractions. Think of the f-number as the denominator, and it starts making sense. An f-stop of f/16 is a smaller fraction compared to an f-stop of f/2.0. Hence, the lower f-number is larger as a fraction, while the higher f-number is smaller.


From left to right, the f-number goes from lower to higher, while the aperture size goes from large to small.

Let’s try a quick exercise. Which is the larger aperture f/1.4 or f/16? Which is the smaller aperture, f/4 or f/5.6? If you answered f/1.4 and f/5.6 respectively, then you’ve got it.


It’s also important to note that there are pre-determined f-stop increments that indicate when the aperture doubles/halves in size. The image comparison above shows exactly that. When it jumps from f/2.8 to f/4, it means that the aperture size is halved. If it moves from f/11 to f/8, this means that the aperture is now twice as large. The doubling increments are as follows: f/1.4 - f/2.0 - f/2.8 - f/4.0 - f/5.6 - f/8.0 - f/11 - f/16 - f/22.

Are there any aperture values in between these increments? Definitely. For example, between f/1.4 and f/2.0, a DSLR can switch in 1/3 increments, yielding f/1.6 and f/1.8. It’s just that these indicated increments have become the norm.

When we make the aperture smaller, it’s often called “stopping down.” Making the aperture larger is also called “opening the lens.”

(Note: An aperture value of f/2.0 to f/4.0 does NOT mean that the size is doubled, even if it looks like the number has doubled. Memorize the indicated double increments to correctly determine when the aperture has doubled or halved in size.)

Minimum and Maximum Lens Aperture

When I started fiddling with my aperture settings, I noticed that it seems to hit a limit, especially for setting a larger aperture. I wanted to go down to f/1.4, but my lens could only go as low as f/3.5.

I learned that it’s simply physically impossible. The aperture is a physical component of the lens, and if your lens isn’t built to go as low or high as you want to, then it simply won’t.

You can check the aperture range of a lens you’ll purchase by checking its minimum and maximum specifications. However, people and manufacturers value the largest aperture setting more since this is what lets more light in and determines how shallow your depth of field can go. As a rule, lenses indicate the lowest f-stop in their name.

Lenses that can go as low as f/1.8, f/1.4, or even f/0.95, are “fast.” A “slow” lens tends to have a maximum aperture of f/3.5 or f/4. The minimum aperture isn’t a problem since most lenses have a minimum aperture of f/16, which most people won’t use anyway.

“Fast” lenses tend to be more expensive. That’s because the mechanical components require more complexity than a “slow” lens. Kit lenses, which are considered beginner lenses since they’re cheap, tend to max out at f/3.5. If you want a faster lens, you’ll have to invest more. The trade-off is worth it, though, especially if you’re a portrait photographer.

Variable Aperture vs. Constant Aperture

Zoom lenses (typically the kit lens) usually have what is called “variable aperture.” When you adjust the zoom of your lens, it also adjusts the maximum aperture value. The maximum aperture is indicated in the lens description as two f-numbers.

Take the kit lens Canon 18-55mm f/3.5-5.6.  That f-number range means that it’s a variable aperture lens. When your lens is at its widest zoom angle (in this case at 18mm), then the maximum aperture you can get is f/3.5. But as you zoom in, the maximum aperture gets higher, and at a certain point within the zoom range, the largest aperture will be f/5.6.

Sony FE50mm lens

The Sony 50mm f/1.8. As indicated in the lens name, the maximum aperture is f/1.8

Not all zoom lenses have this limitation. The Canon 24-70mm f/2.8L lens maintains a constant f/2.8 aperture throughout the zoom range. However, these zoom lenses will cost way more.

Prime lenses have only one focal length, so there are less complicated moving parts inside the lens. A prime lens has the advantage of generally having a higher maximum aperture compared to zoom lenses.

Aperture and Exposure

Changing the aperture size controls how much light passes through the lens into the sensor. If you turn your aperture to the widest setting, then there’s more room for light to enter. Conversely, a small aperture means less light enters. More light means a higher exposure and brighter image; less light means lower exposure and a darker image.

At night-time or poorly lit scenes, you’ll likely want a wide exposure to maximize the little amount of light in the environment. If it’s very sunny, then a smaller aperture will prevent your photo from being overexposed. There are lens filters that can allow you to shoot wide apertures even if there’s a lot of light, but let’s focus on the basics.

Depth of Field and Bokeh

The second most significant impact of adjusting the aperture is changing the depth of field. The depth of field is the area in the photo that is in focus and sharp. We describe the depth of field as being shallow/thin or deep/large. Having a shallow depth of field means that the background and foreground of where your focus point is will be out of focus and blurrier. If the depth of field is deep, then more background and foreground will be in focus (though not as sharp as the focus point).

To make it easier to visualize the effect, take a look at the photograph below:


A wide aperture and shallow depth of field ensure that the subject is effectively separated from the background

In this photo, the large aperture created a shallow depth of field to isolate the subject from the background. As you can see, the subject is sharp and focused, while the background is very blurry. The shallow depth of field dramatically reduces the background distractions, directing the viewers’ attention to only the subject.

On the other hand, I will use a smaller aperture in architectural and landscape photos to get a large depth of field. Why? Because landscapes and architecture shots have large and expansive subjects, so more of the scene needs to be in focus.


To capture the breadth of the landscape, both close and far elements needed to be in focus. That’s why I used a small aperture for that large depth of field

Here’s a side-by-side comparison to help you better visualize the depth of field effect:

Again, to put it simply: a large aperture means more blur and out of focus elements; a smaller aperture means less blur, and more of the scene will be in focus.


This blurry background is also called “bokeh,” the Japanese term for “blur.” A strong bokeh effect is especially useful for portraits if you want to direct the viewer’s attention to the person. Wide apertures like f/1.4 also blur singular light sources, causing “bokeh balls.” The shape of the aperture also determines the shape of the bokeh lights (a hexagonal aperture hole creates hexagonal bokeh lights). Portrait photographers use the bokeh effect to create stylized and atmospheric portrait shots.


Bokeh balls add to the aesthetic appeal of the image

How wide open your aperture is also determines the bokeh light shape you get. When it’s stopped down, the bokeh will show edges depending on edges created by the closing aperture blades. This is due to the shape of the aperture made by the blade edges, and because the bokeh won’t be that strong. However, when you open the aperture, the aperture blades create a smoother rounded hole and stronger bokeh, making the lights look creamier and blurrier.

Bokeh is a subjective quality. The lens’s characteristics influence the type of bokeh you’ll get at the widest aperture setting. I can’t objectively tell you that this bokeh quality is better than the other because it relies on personal taste in aesthetics. One thing’s for sure, though: you won’t get that much bokeh if you don’t have a lens that can open wide, like an f/2.0 or faster lens. If you want that “bokeh-licious” quality in your photos, get a fast lens.

Correct Aperture Settings

Let’s do a quick recap. Again, the aperture significantly affects both the brightness and depth of field of your photo.

When the scene is too bright, like on sunny days, I’ll likely use a smaller aperture to avoid an overexposed photo. I imagine the way my pupils naturally become smaller when staring at bright things to correct the exposure.

But when it’s night-time or in a darker environment, I’ll turn to a larger aperture to ensure that I get enough light for a well-exposed photo. It’s like the way my pupils dilate when I need more light to see correctly.

Aperture also determines if you have a shallow or deep depth of field. If you need more bokeh for subject separation from the background or foreground as portraits usually need, go for a wide aperture and shallow depth of field. But if you need more of the scene in focus, like landscape shots, use a small aperture for a deep depth of field.

Of course, you can adjust the shutter speed and ISO to compensate for the exposure settings. For instance, if it’s too dark and you’ve maxed your aperture, you can make the shutter speed slower for a brighter photo. Or, if it’s too bright, you can use faster shutter speeds.

You might be thinking, what if I want to shoot a portrait with lots of bokeh during a sunny day? I’ve made my shutter speed as fast as possible, but the photo is still too overexposed?

There’s an accessory called the ND filter that you can attach to the front of the lens to make the scene darker, allowing you to shoot wider apertures even in bright conditions. These are like sunglasses for your eyes. They’ll let you shoot wide apertures on bright or sunny conditions without overexposing your photo.

Recommended Aperture Ranges

To give you a more comprehensive understanding of how to apply aperture to different scenarios, here’s a list of the different aperture ranges and what they’re best used for:

  • f/0.95 - f/1.4: These are extremely fast lenses that guarantee bokeh-licious quality. Only the top-notch (and often expensive) prime lenses will offer you this wideness. Portrait photographers love lenses with large apertures for excellent subject and background separation. It’s also particularly useful for low-light conditions since you can take in as much light as possible, especially in events where you have to capture the moment with fast shutter speeds.
  • f/1.8 - f/2.0: If your budget can’t stretch enough, but you still want the closest bokeh-licious experience, lenses in this range will do the trick. Though not as crazy fast as the f/1.4 and faster lenses, these lenses can still offer pleasing bokeh, excellent subject separation, and fantastic low-light capabilities.
  • f/2.8 - f/4: Premium zoom lenses often hit f/2.8 as their widest aperture. Most variable aperture zoom lenses like regular Nikon or Canon kit lenses start at f/3.5. For the capability to zoom in and out, you’ll have to trade aperture width, but at f/2.8, you’ll still get good subject separation and decent bokeh. Since the depth of field is also not extremely shallow, like an f/1.4 lens, your subjects will be sharp and detailed. A zoom lens in this aperture range (ideally with a constant aperture) offers the best balance of lens versatility. Sports, wildlife, and travel photographers often have lenses that fall in this category.
  • f/5.6 – f/8.0: We’re starting to enter landscape photography territory. If you’re taking photos of large landscapes and architectural shots, then getting a lot of the environment in focus is important. At f/5.6 to f/8.0, many lenses will hit the sweet spot for sharpness, so you can be confident that the scene will be very detailed.
  • f/11 - f/16: For much more expansive architectural and landscape shots, stopping down to f/11 or f/16 will help retain more of the scene in focus. This aperture range falls under macro photography, too. Wide apertures almost always produce blurry subjects at close distances since a very shallow depth of field has a large margin of focus error. However, diffraction also starts creeping in at this range.
  • f/22 and higher: Shooting at this aperture range is extremely rare. Sharpness and detail start taking significant hits here, and diffraction becomes very noticeable.


Given the explanations you’ve read about depth of field and smaller aperture, it might make sense to just completely stop down at the minimum aperture when you’re taking a landscape photo.

Unfortunately, it’s not that simple.

Take a look at this comparison of a cropped photo taken at f/4.0 and f/32:

Notice the difference in sharpness and contrast? It looks like the f/32 photo is a lot less detailed than the f/4.0 one. But that doesn’t make sense! I told you that smaller apertures mean more depth of field, resulting in sharper images overall, right?

That’s why we also have to learn about the phenomenon of diffraction.

It’s a concept in the field of optics that physics majors should know in expert detail. However, for us laypeople, a simple explanation should suffice.

At higher f-stops, the aperture becomes tinier, so there’s a smaller space for light to pass through. Imagine the light trying to squeeze into that small hole. All that light bends more than if it had a bigger hole to pass through. When it comes out, the waves become more spread out. The result is a muddier looking photo.

How much diffraction starts to appear depends mostly on the lens quality and sensor size. Some lenses that have cheaper construction can show signs of diffraction at a wider aperture than a premium lens. A smaller sensor size also typically produces more diffraction compared to a larger sensor. On a full-frame camera, an f/11 aperture is valued at f/11. But on a Micro Four-Thirds camera, which is twice as small as a full-frame sensor, f/11 on a lens is valued at f/22. (You can read more about why this happens in the article on sensors.)

The full-frame camera I use starts showing a bit of diffraction at f/11. But that’s only noticeable if I look at the photo up close. In general, stopping down at f/16 and f/22 will make the diffraction much more apparent. That’s why it’s best to avoid those small apertures to get maximum sharpness and detail from your photo.

However, stopping down yields more depth of field, which allows a wider part of the scene to be in focus, so there are still some benefits. It’s up to you to test your lens capabilities and study the optimal aperture for different scenarios.

Lens Aberrations

Let’s make this clear: no lens will be perfect! Lens aberration is a general term for all the imperfections and quality issues, however minor, that are inherent with lenses. Aberrations cover things like distortion, color fringing, and vignetting. As the saying goes, “it’s not you, it’s me”—and the “me” here is our lens.

Of course, premium lenses are built to minimize potential aberrations. Manufacturers come up with different ways in the lens construction to ensure that the optical quality is at its best, whereas cheaper lenses generally have less complexity put into them, so aberrations will occur more often. In this case, pricing is likely proportional to lens quality.

The corners of the lens’s optical elements are more challenging to design. As a result, the quality suffers more at the edges, and the aberrations often appear at the corners of your photo. The center will display the least amount of aberration if any, so it’s the standard by which most photographers compare their photo’s corners. Take a look at this diagram that shows the optical components of the lens:

Zeiss Otus 55mm f 1.4 lens

If the aberration is inherent in the lens, then why are we discussing it in an article about aperture? Well, that’s because aperture settings can help minimize the degree or intensity that certain aberrations occur.

As the aperture closes, it blocks off the light passing through the edges of your lens. Your photo still has light at the corners because the sensor still receives light that passed from the center of your lens instead (do note, however, that some lenses will vignette at certain apertures due to their construction). The smaller your aperture is, the more you minimize the poor optical quality you get from the lens corners. The result is that you get the best image quality from the lens’s center.

Have a look at this comparison where the same subject was shot at different apertures:

It looks sharper and more detailed due to the smaller aperture, and that’s largely thanks to the reduced aberration as well. At the wide-open aperture, the aberrations are more likely to pop up since the lens’s corners are more exposed. But again, premium lenses are designed to mitigate aberrations at wide-open settings.

This phenomenon occurs alongside diffraction, though. The trade-off you get for blocking the poor lens corners will eventually see diffraction kick in at small aperture settings. To know what the optimal aperture is at minimizing both aberrations and diffraction, you need to be familiar with your lens capabilities.

Lastly, some aberrations aren’t necessarily prevented by stopping down your lens. Some color fringing doesn’t disappear simply by using a small aperture; the problem isn’t the corners of the lens but something inherent with the lens quality itself. This is completely fine, and such aberrations are typically insignificant and unnoticeable. They might only be seen if you try extremely hard to look for them.

Starburst and Sunstar

On the opposite side of those creamy bokeh balls, lenses can also produce starburst or sunstar effects from light sources.

How do you get this effect? It’s simple: if you get bokeh balls by opening your lens, you get starbursts by stopping down your aperture. This can only occur from singular, bright light points in the scene.  Here’s a photo example:


The landscape photo was shot at f/16

The number of beams you get depends on how many aperture blades there are in the lens—e.g., six aperture blades yield six sunbeams. But—and here’s the weird part—if you have an odd number of aperture blades, you get twice the sunbeams—e.g., seven blades produces fourteen sunbeams.

It was strange the first time I heard about it, but this phenomenon is easy to explain. There are also twice as many sunbeams in even-numbered aperture blades; however, due to the symmetrical construction of the aperture, one sunbeam will overlap with another sunbeam, causing the total sunbeams you see to be halved. Odd-numbered aperture blades don’t have this effect.

Take a look at this diagram to picture it more easily:


Aperture shape also determines the sunburst shape you get. Aperture blades that have straight edges will produce more distinctive sunburst patterns than blades that are rounded. If you want that starburst effect, take a look at the aperture blades of your lens and test it out at different apertures.

Sunbursts are usually achieved with streetlamps or shafts of sunlight being filtered by some obstacles like leaves. This involves pointing your camera directly towards the light source. However, one potential side effect of this is an aberration called lens flare.

You might get the achieved sunburst effect at the expense of some flare. However, this can usually be remedied by changing your shooting angle or position. Others may prefer this flare effect, so they try to bring it out on purpose.

Faster Focusing

When your camera uses autofocus, it needs enough light to detect and process the scene properly. Without enough light, it will struggle with limited information to detect what the correct focus point is.

When we stop down our aperture and auto-focus, the camera doesn’t focus using that small aperture. It still opens as wide as possible to focus properly first. If your lens’s widest aperture is f/2.0 and you set your aperture at f/11, your camera autofocuses at f/2.0. When you click the shutter button, that’s when the lens uses the f/11 aperture you set to take the photo.

Naturally, if your zoom lens’s widest aperture is, for example, f/4.0, it might not be able to focus as effectively as a prime lens with an f/1.4 aperture. This problem is exacerbated by low light conditions where your autofocus will start missing more shots; in well-lit scenes, the autofocus difference between an f/1.4 and f/4.0 lens can be negligible.

If you want to have better autofocus speed and accuracy, you’ll do better with a faster lens. Landscape photographers need not worry about this much since they have enough time to set the focus properly. But in scenarios where things happen quickly, like sports, a wider aperture can make a huge difference.

Focus Shift

When you change your aperture, your focus point may also shift ever so slightly. When that happens, it’s called focus shifting, and it happens even if you have your camera on a tripod, your lens is on manual focus, and you don’t make any adjustments to the focus.

Focus shift is also another quality that is inherent in the lens design. You can even consider it another lens aberration. Your lens focuses differently wide open since light focuses differently as it passes through the lens’s corners. Stopping down blocks the edges and limits your focused light at the center, thus slightly affecting your focus point and resulting in unintentionally blurry details that you’d want to avoid.

You can test how bad your focus shift is by doing the following steps:

  1. Place your camera somewhere steady, preferably using a tripod, and put it on manual focusing mode.
  2. Use a detailed object like a heavily ornamental piece of cloth. Place it in front of the camera and extended away. Have your camera focus on the object’s center.
  3. Take a series of photos while stopping down the aperture at double increments in each photo. You must adjust only the aperture; don’t do anything to change the focus like turning the focus ring. The focus point must remain at the center of the object.
  4. Now, export these photos and take a look at the progression using your computer. Time to do some pixel-peeping. Zoom your preview into the center of the object.
  5. Did the focus shift away or towards the camera, the more your aperture became smaller and smaller? By how much did it move? If the movement is very minimal and barely perceptible, then it’s fine. But if the movement was drastic or noticeable enough, then you have some major focus shift occurring.

With every brand-new lens purchase, I make it a habit to check my lens’s focus shift using this simple test. After all, knowing my lens’s quirks allows me to maximize its capabilities.

It’s not all bad, though, just because your lens has focus shift—it’s perfectly normal. If the shift is significant, you’ll just have to learn how to compensate and adjust accordingly. Know what aperture/s the shift occurs and how to move your camera or adjust your focus to get the correct focus point. At very small apertures like f/11, the wide depth of field can already compensate for whatever focus shift occurs.

You don’t have to be mindful of focus shift when you’re shooting at wide apertures. Modern lenses are mainly designed to focus with the aperture wide open. Doing so allows the lens to process the scene with as much light information as possible.

With the wonders of camera advancements, you can enter live view mode and use focus peaking on your camera’s LCD screen. Using those features allows you to get pinpoint focusing accuracy as much as possible. With our modern camera technology, focus shifting isn’t much of a problem anymore.

Other Problems Using Smaller Apertures

Smaller apertures also tend to show elements that you don’t want in the photo. When those elements appear, it may be due to them being too close or on the lens. It’s also possible that they’re on the sensor itself.

Why is that? As discussed before, a smaller aperture means a larger depth of field, meaning that more elements in your scene are in focus. As a result, the increased depth of field can catch those elements that were too out of focus or tiny for you to notice, if you had used a wider aperture.

When it’s a rainy day, you’ll likely get unwanted droplets to fall on your lens, which typically won’t be a problem if you shoot wide open. The depth of field is shallow enough that the camera won’t even register these droplets. When you stop down, that’s where it can get ugly. You might not notice it as you’re shooting, but when you come home and transfer these photos on your computer, the bigger screen will give them away. As a rule, I make it a habit to inspect the front of my lens during landscape shots where a small aperture is needed.

But what if these droplets are on a window, and your subject is across it? If there’s no way to wipe it if the droplet is outside, shoot at the widest possible aperture and check if the droplet appears on the photo. I’d try to incorporate it in my scene and intentionally shoot at a smaller aperture. Don’t think that these elements are necessarily blemishes or imperfections on the photo; sometimes, they might be what you need to give your photo that special something.

Water droplets aren’t the only elements you’ll encounter. Dirt and dust specks can also be a nuisance (and they’re likely less aesthetic, too). Compensate your aperture setting as needed to remove (or add) these elements.

In some cases, you might be shooting behind a fence, net, or something similar. Using a wide aperture makes the fence wires disappear while smaller apertures will show their blurry outlines. Ask yourself if you want to make it part of the scene. If not, then shoot as wide open as possible.

At this point, I feel like it’s also important to discuss sensor dust.

When we change lenses, we expose our sensor to the environment around us. The environment can contain dust particles that might land on your sensor. Nowadays, most cameras have automatic sensor cleaning capabilities by vibrating the sensor just enough to shake off those pesky dust particles that landed on it. Some cameras won’t have this feature, though, or maybe the sensor hasn’t cleaned itself yet, and you’re already taking shots without knowing about the sensor dust.

At wide apertures, these dust particles are practically invisible. But at smaller apertures like f/16, they’ll start to become noticeable blemishes on your photo. But they’re easy to remove with cleaning tools in post-processing software. The dust might even be unnoticeable since they blend with the photo. Of course, keeping your sensor clean helps ensure that you get the best image quality. Inspect your sensor regularly, clean it using the right tools, and turn on the automatic sensor cleaning feature if your camera has it.

Flash Exposure

We won’t delve much into the relation of aperture setting and flash equipment—we have a separate article explaining exactly that. But to make a quick note on this: when using flashes like strobes and speedlights, aperture determines how much light the camera will register from the flash output. If you use flashes in your photography, consider reading our other article about flash exposure.

Guide Chart for Aperture Effects

I know, I know—it’s a lot to take in. I had to revisit a lot of key concepts when I was just learning more about photography. What helped me was a guide to remember how different aperture settings affect my photos in multiple ways. To help you, here’s a handy chart you can use as a reference:

This chart isn’t the most comprehensive guide you can find out there, but it’s better than nothing, and it illustrates a lot of the key concepts we’ve discussed so far in an understandable way. Keep practicing shooting at different apertures. Observe how your photos come out differently whenever you adjust your aperture settings. Be detail-oriented when you study your photos. Eventually, all of these concepts will become second nature to you as a photographer.

Here's another useful beginner’s chart if you want to simplify it further:

Frequently Asked Questions

Here are some questions about aperture that I often get:

What is the aperture?

The aperture is the mechanical opening of the lens that allows light to pass through the lens.

How do I measure aperture?

Aperture is measured in f-stops or f-numbers. It’s denoted by “f,” followed by a slash or not, then the aperture value—e.g., f/2.0. The lower the number, the wider the aperture size; the higher the number, the smaller the aperture size.

What is my lens’s maximum aperture?

It depends. Not all lenses are made equally. Some lenses can open wide like f/1.4 or f/0.95, while others stop at f/3.5. Manufacturers attach the lowest aperture of the lens to its name. Some lenses have variable aperture, meaning their maximum aperture changes depending on how much the lens is zoomed in.

How do I change the depth of field using aperture?

When your lens has a focus point, the depth of field is the amount of distance in that focus point that is sharp. Having a large aperture grants you a shallow depth of field, meaning that the background and foreground of the focus point are blurrier. A small aperture grants you a deep depth of field, so the background and foreground appear more focused.

What is bokeh?

Bokeh is a Japanese term for the out of focus or blurred elements in the photo. A wide aperture means that you get blurrier bokeh. The bokeh quality is sometimes described as creamy or smooth. Light sources also produce bokeh balls due to the shape of the aperture. For example, a hexagonal aperture yields a hexagonal bokeh ball, while a round aperture yields round bokeh balls.

How do shutter speed and aperture work together?

A wide aperture means more light enters the lens into the sensor. Therefore, you can use a faster shutter speed to keep your scene frozen more since there’s enough light from the lens. If your aperture is small, then you might need to use a slower shutter speed for the sensor to absorb the light and get a properly exposed image.

How do I get my entire scene in focus?

If you want to get the most focus in the scene, then stop down your lens to the smallest aperture. Don’t position the camera too close to the subject either. Move a bit farther away so the foreground and background will also be more in focus.

What is better: higher or lower aperture?

To answer this question, you have to know what kind of photo you’re taking and what effect you want to achieve. Do you want a lot of bokeh? Do you need to separate your subject? Do you want to draw attention away from the background? Then a lower aperture is better. Do you need more parts of the scene in focus? Are the foreground and background equally important? Do you want more detail and sharpness? Then a higher aperture is what you need.

What is the sharpest aperture of my lens?

Some lenses have what is called the optimal aperture or sweet spot. The sweet spot is the aperture where your focus point is sharpest and least prone to focus shifting and diffraction. It’s hard to answer this without knowing the exact lens and testing it. However, many lenses find their sweet spot at f/4.0 or f/5.6.

What aperture do I use for portraits?

Generally, portrait photographers use a large aperture for subject and background/foreground separation. The subject remains sharp while the rest is out of focus. An aperture of f/2.0 or larger will do nicely. Prime lenses are preferred since they feature generally wide apertures.

What aperture do I use for landscapes?

Landscapes shots feature wide foregrounds and backgrounds so that they will need a large depth of field. You should use a small aperture like f/8, f/11, and f/16.


Reaching the end of this article must’ve been tiring, I’m sure. We discussed tons of concepts related to aperture, which only proves that aperture is an extremely important function to understand in photography.

It seems like a daunting task to remember all these things at once. You might fumble around (like I did) a bit at the start: How do I get more blur again? Why is my photo a bit blurry even if I used the smallest aperture? How do I get those pretty sunburst effects again? You might have to review a concept or two again to refresh your memory.

But I want to assure you that it gets so much easier. Changing aperture and knowing what follows after has become as natural as breathing to me as a photographer. I don’t even have to think about it too hard anymore. My fingers just move by themselves to adjust the aperture depending on the scene and the output I want to achieve. I’m not saying these things to make you feel incompetent if you’re a beginner; I’m saying this because I know you’ll get there, too.

Ultimately, the best way to make aperture setting second nature to you is to keep on shooting and shooting, read up if you need a refresher, and never be afraid to see where different aperture settings will you take your photos!

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