What is the aperture in photography? Why does aperture matter? And most importantly, how does lens aperture affect your image?
As an amateur photographer with five years of experience, I often get asked this from new photographers.
Aperture in photography is one of the three essential components of the exposure triangle, along with the ISO value and the exposure time/ shutter speed. Aperture plays a vital role in creating a quality image.
In this post, I will help you better understand what is aperture in photography, how aperture in photography works, and how to choose the best aperture to take great images.
What is Aperture in Photography? – It’s All About Light
Aperture refers to a hole in a lens through which light enters the camera sensor. In other words, the lens aperture controls the amount of light that passes through the camera lens.
The simple rule is a larger hole allows more light to reach the camera sensor, resulting in a brighter picture.
Conversely, a smaller hole allows less light to pass through the camera lens to the image sensor, resulting in a darker picture.
A Large Hole = More Light
A Small Hole = Less Light
Understanding Aperture: What Is a Lens’s Diaphragm?
The diaphragm is the lens opening of your camera that can be opened or closed further to let light enter the camera.
The diaphragm is formed by aperture blades. These blades slide over each other to create a large or small hole in your lens so that the right amount of light enters your camera. Not too much, not too little.
Depending on the price and quality of the lens, most lenses have 5 to 12 blades.
The Red Arrow Indicates the Aperture Blades, and Blue Arrow Indicates the Aperture.
What Are F-Stops and F-Numbers?
Many beginners get confused with f-stops and f-numbers. Technically speaking, f-stops and f-numbers are terms used to indicate aperture measurements on your camera.
The f-stop (or f-number) describes how much light the aperture allows into the camera lens, with the letter “f” appearing before the number.
The f-stop (or f-number) usually ranges from f/1.2, f/1.4, f/1.6, and f/1.8 to f/32 on your lens.
What are Common F-Stops and F Numbers?
The most common F-stop values follow a sequence on the aperture scale as follows:
- f/1.4 – the largest aperture opening to let in as much light as possible.
- f/2 – from f/1.4 to f/2 is one stop, let in half as much light as f/1.4.
- f/2.8 – from f/2 to f/2.8 is also one stop, let in half as much light as f/2.0.
How Are F-Stops / F Numbers Calculated?
F-numbers are determined by the ratio of the effective aperture diameter
of the lens (or you can call it the size of the lens opening) to the focal length of a lens.
F-Number = Focal Length (f) Divided By effective Aperture Diameter
What Is a Large and a Small Aperture?
The combination of the diameter of the aperture and the focal length determines whether more or less light passes through the lens.
By adjusting the camera’s aperture settings, you actually increase or decrease the size of the aperture in relation to your current focal length.
A Low F Number = Aperture Size Increases = More Light = a Larger Aperture
A High F Number = Aperture Size Decrease = Low Light = a Smaller or Narrower Aperture
For example, f/1.4 is a much larger aperture than f/16.
Minimum and Maximum Aperture
All cameras have minimum apertures (as low as f/22 with some lenses) and maximum apertures (as high as f/1.2 with some lenses), which are the aperture settings that let in either the least light or the most light.
For example, if a camera lens has an aperture range of f/1.4 to f/16, the minimum one is f/16, while the maximum is f/1.4.
A lens with a maximum aperture like f/1.4 is often considered a “fast lens”, which is more expensive since it allows more light and results in faster shutter speeds.
While smaller apertures like minimum aperture let in less light, which requires longer shutter speeds to allow more light onto the sensor.
Different lenses have different maximum and minimum apertures. Prime lenses usually have larger maximum apertures than zoom lenses.
What Is Constant Maximum Aperture?
It’s the maximum aperture or widest opening the zoom lens can open up for each end of the zoom range.
More expensive zoom lenses tend to have a constant maximum aperture of f/2.8 to f/4 throughout their zoom range, like canon lenses RF 24-70mm f/2.8.
Be sure to check out the maximum aperture when buying a lens.
What Is a Medium Aperture for a Lens?
A medium aperture is a medium opening of the lens, which allows it to capture more light. A medium aperture is related to middle F-stop values, usually somewhere between f/4 and f/11.
What Is the Optimal Aperture for a Lens?
The optimum aperture (also called the sweet spot or optimal opening ) of a lens is the f-number (or aperture number) at which your lens
- produces the best sharpness
- reduces distortion
- and minimizes chromatic aberrations
In other words, the aperture with which the lens works best.
In general, an optimal aperture is not at its optimum at full aperture, nor with the diaphragm completely closed.
The optimal open is about two to three f/stops lower (i.e. say more closed) than the full aperture.
For example, the sharpest/optimal aperture on my Sigma 35mm f/1.4 is between f/2.8 and f/4. Sony telephoto lens like 70-200mm F/4.0, has a sweet spot between f/8 and f/11.
How to Know the Optimal Aperture of A Lens?
The best way to know for sure your lens’s sharpest aperture is to do your own tests.
On tripods, test several openings on a subject, so you can see what’s going on and find the sweet spot that works best for you.
How to Use Aperture in Photography
Aperture has several effects on your pictures. Basically, we use aperture to:
- control the amount of light (exposure).
- create the depth of field (Depth of field refers to the area within an image that appears sharp and in focus).
When shooting, we rely on aperture to control the amount of light reaching the camera’s sensor and adjust the depth of field – how sharp or blurry objects appear in your picture.
How Aperture Affects Exposure and Shutter
Mastering exposure is essential for beginners, advanced amateurs, and professionals.
Together with shutter speed, ISO, and aperture, aperture has a direct impact on exposure as below:
- A low F-stop (such as f/1.2, f/1.4, f/1.6, f/1.8) = large aperture (big hole), meaning:
- More light travels through the lens leading to a brighter picture
- A faster shutter speed is required to make a correct exposure.
- A high F-stop (such as f/16, f/22) = small (narrow) aperture (small hole), meaning:
- Less light travels through the lens leading to a darker picture
- A slower shutter speed is required to make a correct exposure.
If too much light has been allowed to pass through the image sensor, the image captured will be overexposed. Conversely, too little light will give you a very dark, underexposed image.
Adjusting the aperture for your lens based on environmental conditions helps achieve the proper exposure you desire.
Understanding Aperture and Depth of Field in Photography
Depth of field refers to how much of your image is in focus. By setting the aperture you control depth of field, emphasize certain parts of your picture, and blur other parts.
Aperture Controls What is in Focus and What is Out of Focus
Aperture controls the amount of depth of field in your pictures as below:
- A low F-stop (such as f/1.2, f/1.4, f/1.6, f/1.8) = large aperture (big hole).
- More light travels through the lens
- Small focused area (a very shallow depth of field)
- A high F-stop (such as f/16, f/22) = small (narrow) aperture (small hole).
- Less light travels through the lens
- large focused area (deep/large depth of field)
How to Use Depth of Field
Adjusting the depth of field is very important when composing a picture.
If you want to keep everything in the image sharp, crisp, and clear, use a small (narrow) aperture to achieve a deep depth of field.
When shooting landscape, a deep depth of field is a critical component of every image you take, providing edge-to-edge, front-to-back sharpness.
On the other hand, you can use a very large aperture (a shallower depth of field) to highlight the main subject and make lots of scenes out of focus.
When shooting portraits, wildlife, and sports, shallow depth of field makes the main subject stand out from a blurred background.
When to Use Maximum and Minimum Aperture
When to use a higher or lower aperture depends both on the type of photography and your artistic vision.
The maximum aperture impacts the type of pictures you take, and it is largely used for portrait, and wildlife photography.
However, in macro photography, landscape and architecture photography, photographers often utilize small (narrow) apertures such as f/11 and f/13 to get sharp with both the foreground and the background.
Advantages of Large Aperture
Shooting with a wide/large aperture has several advantages:
- more light means overall sharpness
- produce more detail
- capture as much light as possible in low-light environments like outside right after sunset
- blur background
- possible lower ISOs for better image quality
Creating Blurry Backgrounds with Large Aperture
A blurred background picture draws the viewer’s attention because it gives the viewers a focus point and makes pictures look more professional.
In some of the beautiful portraits and wildlife pictures, the subject is super sharp, but the background is out of focus. This is because wide apertures help you create that blurriness.
Ideally, wide apertures such as F/1.4, F/2, F/2.8, and F/4 enable you to create soft background blur.
Just remember that the smaller your f-number, the blurrier your background.
Sometimes you struggle to get perfect blurred backgrounds. So experiment with different apertures and see in which one the background is soft and smooth.
Moreover, moving your subject away from the background also helps you get blurrier backgrounds for portrait photography.
Advantages of Smaller Aperture
Small (narrow) apertures are often used to control the amount of depth-of-field. It has several advantages such as:
- deep depth of field
- less light for capturing long exposure photography like the night sky, light trails
- create sunstars
- keep everything in focus
Creating Sunstars with Small Aperture
You may have already noticed that the sun looks like a star in many landscape pictures – beams of light radiate from the sun.
Adding those extra sun stars to your landscape and wildlife images transforms your pictures from a generic shot to something more attractive, and eye-catching.
A typical sun-star effect requires a small aperture and a partially blocked sun or street lights in night photography.
if you’re a landscape photographer and you want everything as sharp as possible, then a smaller aperture is better for the starburst effect.
Typically, a small one around the f/16 – f/22 range is perfect for making sharper, crisp-looking stars.
How to Adjust the Aperture With Your Camera
In digital photography, you can set the aperture manually or allow the camera to do it for you automatically.
There are a few options you can adjust aperture on your mirrorless camera or DSLR:
Auto Mode (Auto)
The camera automatically chooses the optimum aperture, shutter speed, ISO and white balance, etc. according to your environment. So you just point and shoot, and no need to change the aperture.
Aperture Priority Mode (Av or A)
You select the desired aperture and ISO, white balance, etc., while your camera automatically chooses the proper shutter speed according to the environment.
Some cameras label aperture priority as AV (for Canon camera’s) or A (for Nikon camera’s) on a mode dial. Aperture priority mode works best with natural light portraits.
By the way, there is a also shutter-priority mode (s) – you choose shutter speed while the camera adjusts an appropriate aperture based on the environment you are shooting.
Manual Mode (M)
Manual mode is best if you want to fully control aperture, shutter speed, exposure, blur, and focus over your camera settings.
Unlike aperture priority mode, you change the aperture, shutter speed, ISO, etc, with manual focus adjustments to achieve proper exposure.
Manual mode can be challenging for beginners; however, it also gives you more creative freedom and forces you to learn more about your camera.
Aperture for Landscape Photography
Landscape pictures describe the earth’s most amazing places to the viewers and create a connection to nature. Photographers find endless inspiration in nature.
You’ll want to use small apertures ranging from f/8 to f/13 to keep everything in focus in landscape photography.
Generally, the best aperture for landscape photography is below f/16 or so.
Aperture for Portraits
Portraits are compelling when they tell us something about the person.
Portrait photography is about understanding light. If you get your aperture wrong, you may have too dark or too bright portrait pictures.
Wider apertures ranging from f/1.4 and f/4 collect as much light as possible in portraits, and work best to
- create a shallow depth of field
- keep the main subject in focus
- and blur the background.
Aperture for Street Photography
Street Photography allows us to explore the world differently.
During bright sunny days, the best aperture for street photography is between f/5.6 and f/9 to capture
- and unposed moments
Motion blur can make your street photography come to life. Set your aperture between f/8 and f/16, along with slow shutter speeds between 1/30 and several seconds, and you can get a fun motion blur for your street shots.
Additionally, you need enough light for sharp pictures.
Aperture in photography is one of the three essential pillars of the exposure triangle.
Understanding how aperture works helps you improve your overall photography skills and opens up new creative possibilities.
So pick up your camera—practice working under challenging situations. Consider when you should or shouldn’t use a wide or small aperture.
The more photos you take, the more you’ll learn. Get out there and start experimenting!