The first time you set out to buy new lenses for your camera, you may find yourself confused choosing between fixed (or constant) aperture and variable aperture lenses. What is a fixed aperture lens? What is a variable aperture lens? What’s the difference between a fixed aperture and constant aperture for a lens?
The chart below summarizes the differences between a fixed (or constant) aperture lens and a variable aperture lens:
What it does
Variable Aperture Lens
Lens automatically adjusts the minimum aperture available based on your focal length
More affordable, more compact & lighter
Limited apertures, less options, & need to pay more attention to other exposure settings
Fixed Aperture l
Aperture stays the same throughout all focal lengths
More robust, better image quality, & allows greater creative control
Heavier, larger, & more expensive
Many factors go into the decision to use one type of lens over the other. We will go more into depth on the differences between fixed (or constant) aperture lenses and variable aperture lenses below, as well as a quick discussion of the impact aperture has on your photos. At the end of the article, we also included recommendations for the best lenses for your camera organized by constant or variable apertures.
Fixed Aperture Lenses
A fixed aperture lens is sometimes referred to as a constant aperture lens. This means the aperture of the lens does not change depending on the focal length. Being able to change the aperture regardless of the focal length means that the photographer has much greater control over the photo. With a constant, or fixed, aperture lens the photographer could use a long focal length like 200mm and still be able to choose a larger aperture like f2.8 to allow a lot of light into the camera and in turn, create a shallow depth of field. This is not always possible with a variable aperture lens, which limits the aperture opening (usually to around f/5.6) depending on the focal length.
As with most decisions, there are some compromises when choosing a type of lens so it is important to know the pros and cons of a fixed aperture lens.
- Greater Light Input on Longer Focal Lengths. Generally speaking, fixed aperture lenses allow for more light getting into the camera, which increases your options for exposure and allows you to take photos in low-light situations.
- Increased Depth of Field Options. Because you aren’t limited to specific aperture sizes with this type of lens on the longer focal lengths, you can choose a larger aperture (like f2.8) when using the standard portrait focal length (85mm) but still be able to shoot with a shallow depth of field to make the main subject “pop” from the background.
- Better Vibration Reduction. Vibration reduction lenses have internal stabilizers that help the lens compensate for less steady shooting conditions, such as shooting by hand as opposed to using a tripod at longer focal lengths (say, 200 – 300mm).
- Built Sturdy. Fixed aperture lenses are more usually built with studier materials, like metal instead of plastic. This makes them more robust. Also, they often come with more weather proofing than their counterpart.
- Faster. Fixed aperture lenses are considered professional lenses because they allow the photographer to take photos at faster shutter speeds. This means less concern over moving objects or with an unsteady camera.
- Great for Video. Because the exposure stays the same when zooming to longer focal lengths, as long as your shutter speed and ISO stay consistent, a fixed aperture lens is considered a better choice for video.
- Heavier. With more lens elements inside the lens, fixed aperture lenses weigh considerably more than their variable aperture counterparts. This can be a serious consideration when doing location shooting, where you may have to carry your lenses with you all day.
- Larger. Another side effect of having a number of elements, and the size of the elements themselves, built into the lens is that a fixed aperture lens is going to be a great deal bigger than a comparable variable aperture lens. If storage is at a premium this could make it difficult to fit all the lenses you need.
- More Expensive. All that quality comes with some expense. Fixed aperture lenses are built for durability, control, and utility. The additional engineering inside a fixed aperture lens will cost more than a variable aperture lens.
Variable Aperture Lenses
Variable aperture lenses are easier to make because they contain fewer internal mechanics and lens elements. With fewer components inside the lens, a variable aperture lens is lighter and more affordable than a comparable fixed aperture lens.
Because the aperture changes with zoom level, the photographer will find limited aperture options at different zoom levels. This limitation in flexibility can result in variations of exposure and depth of field and can make it difficult to control the outcome of the final shot.
Despite being generally considered a lower-quality lens, a variable aperture lens may still be the preferred option depending on what you want to do with it.
- Lighter. Fewer lens elements within the housing of a variable aperture lens allow less weight to the lens. If you are packing for a vacation, a lightweight variable aperture lens may be vastly preferable to a heavier, fixed aperture lens.
- More Affordable. Having fewer lens elements inside the housing means manufacturers can make them more affordable than a fixed aperture lens.
- Smaller. Since the size of the glass elements doesn’t need to be as large on this type of lens, variable lenses tend to be much smaller. If you don’t have a lot of room for spare lenses, the more compact size of a variable aperture lens may be the deciding factor when deciding what you can take with you on a shoot.
- Larger Focal Length Range. Often you will find larger focal length ranges in variable aperture lenses (for example, Nikon made a lens that covers 16 mm – 300mm). This is called a superzoom lens). Constant (or fixed) aperture lenses are generally limited to a certain range (for example, to get the same range you would need the 24 – 70mm, 70 – 200mm, 200 – 300mm lenses) so this is one advantage variable aperture lenses have.
- Less Light Input With Longer Focal Lengths. Variable aperture lenses limit the light input on longer focal lengths by moving automatically to a minimum aperture at a specific focal length (for example, f/4 or f/5.6 at 200mm). In general, this means the photographer will have fewer options for exposure when zooming in on the scene.
- Less Depth of Field. Losing aperture control on the longer end of the focal length range means losing control over the depth of field. This might be okay with landscape photography but will limit the application for portraits.
- Less Vibration Reduction. Variable aperture lenses are not as high quality as fixed aperture lenses and tend to have less vibration reduction – if they have any at all.
- Not as Sturdy. Variable aperture lenses are more affordable than fixed aperture lenses, but they are not as durable as their counterpart.
- Lower Quality Glass. Generally, variable aperture lenses are built with affordability in mind and that means it comes with lower quality glass. This means these lenses are not as sharp and more prone to lens distortion and chromatic aberration. This can usually be easily corrected in image editing software but it does add an extra step.
- Need To Pay More Attention to Exposure Settings. Because a variable aperture lens will limit how wide an aperture a photographer can achieve at a specific focal length, it will force the photographer to compensate using other exposure settings like shutter speed and ISO to account for the limited light input.
Other Types of Zoom Lenses
There are several other types of lenses available. A photographer may choose a wide-angle lens, an ultra-wide lens, telephoto, or prime lens. These all offer different zoom levels (expressed in mm) and may come in both variable or fixed aperture options.
Ultra-Wide Angle Lens
An ultra wide-angle lens has a focal length under 20mm. It contains built-in compensators for the fish-eye factor that corrects for the rounded look a photographer may get with a standard wide-angle lens. Both fixed aperture and variable aperture options are available in ultra wide-angle lenses.
Wide Angle Lens
A wide angle lens is one with a focal length of less than 35mm but more than 16mm. A wide-angle lens is great for a spanning panoramic shot at the top of a mountain. If you are able to adjust the zoom of a wide-angle lens, it is likely a variable aperture lens but there are also constant aperture wide-angle lenses are well.
A telephoto lens is a long lens that allows for long focal length that let you zoom in on a subject. They also have narrower depth of field than a wide angle lens. A telephoto lens is often the best option for wildlife photography because it allows distant objects to appear closer to the camera. It is also be used for portrait or product photography. Telephoto lenses come in both fixed aperture and variable aperture lenses.
A prime lens is one that is designed to work at only a specific focal length. There is no changing the zoom level on a prime lens, which means it is intended for a very specific and narrow range of photographic results. Because prime lenses do not zoom they are often lighter in weight then zoom lenses and allow for larger apertures because they don’t have the extra elements (for example, f/1.2 or like this expensive Nikon lens at f/0.95). Common focal lengths for prime lenses are 16mm, 23mm, 35mm, 50mm, 85mm, 100mm, 300mm, and 800mm.
What Is the Aperture and Why Is It Important to Know?
Understanding aperture is one of the most important elements in controlling your camera to get the results you want. Simply stated, aperture describes the size of the opening in the lens through which light is allowed. A wider aperture (like f/2.8) allows more light into the camera, while a narrower aperture (like f/8) limits the light.
Aperture is described using an f-number. These f-numbers are also called f-stops and indicate the width of the opening expressed as a fraction. For instance, f/2 is a very large aperture opening, where f/16 is a very small aperture opening. To make this easier to understand, think of the number as a fraction (because it is) – f/2 means 1/2, where f/16 means 1/16.
The reason it is important to understand aperture when you are choosing between a fixed aperture lens and a variable aperture lens is because the type of zoom lens you choose will have an effect on how much control you can exert over aperture. And it is important to understand aperture because it affects two important things in your photography.
Depth of Field
The size of the aperture – the f-stop – will define the depth of field you get when you take your photo. A large aperture – an f-stop closer to f/1.4 or f/2.8 – will narrow the depth of field of focus in your scene that will be sharp when you take an image. Conversely, a small aperture – closer to f/16 or f/22 – will expand the depth of field of focus and allow more of the elements in the shot to be sharp.
When a photographer is using a variable aperture lens, they will have less access to wider apertures at the longer focal lengths. This means a variable aperture lens will be less effective at capitalizing on photos with variations in focus. A fixed aperture lens, on the other hand, will allow the full range of apertures, since its focal lengths are independent of aperture, and thus allow a much wider range of options in terms of depth of field.
The basic principle of exposure is that the more light is let into the camera, the brighter the photo will be. This may seem obvious – more light results in more light – but it is important to understand your options that aperture allows in terms of exposure.
A smaller aperture allows less light into the camera, resulting in an overall darker photo. A larger aperture, then, offers the opposite effect and results in a brighter photo. Overexposing an image can result in a blown-out photo (one where most of the scene is too bright to know what it is) and underexposure may leave you with a dim image (too dark of an image to make out the details). Shutter speed will also affect the exposure, but in general shutter speed is not determined by the lens.
A fixed aperture lens will allow the photographer a wider range of aperture options. This may allow the photographer a much larger aperture and for night photography, photographing a night sky, or in low light. A variable aperture lens, which will limit how wide an aperture a photographer can achieve at specific focal lengths, will make it difficult to shoot starry skies or achieve a shallow depth of field when shooting portraits.
Why Does the Aperture Change?
Any time a lens zooms, or change focal lengths, it does so by adjusting the distance between various curved elements of glass within the lens. Changing this distance alters the diameter of light that strikes the last piece of glass.
Fixed aperture lenses have many more of these pieces of glass within the lens. The additional pieces of curved glass elements allow the lens to compensate for the zoom level. This allows the photographer to still be able to adjust the aperture regardless of the zoom level.
Best Performing Lenses
There are so many lenses available that it can be overwhelming sifting through your options. After looking through online reviews, we were able to find the best options on the market. For more in-depth looks at the lenses listed below, click the name of the camera system to be taken to the reviews.
These charts list the lenses and the associated camera system. They also include everything from ultra-wide angle lenses to telephoto and prime lenses.
Best Performing Fixed Aperture Lenses by Camera System
Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens, Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens, Canon EF 24-105mm f/3.5-5.6 IS STM Lens
Canon RF 24-105mm f/4-7.1 IS STM, Canon RF 24-240mm f/4-6.3 IS USM, Canon RF 24-240mm f/4-6.3 IS USM
Nikon AF-P DX Nikkor 70-300mm f/4.5-6.3 G ED VR, Nikon AF-S FISHEYE, NIKKOR 8-15mm f/3.5-4.5E, Nikon AF-P DX NIKKOR 10-20mm f/4.5-5.6G VR, Nikon NIKKOR 80-400mm f/4.5-5.6G ED VR, Nikon AF-S 18-35mm f/3.5-4.5G ED Lens
Nikon Z 24-200mm f/4-6.3 VR, Nikon Z DX 16-50mm f/3.5-6.3 VR, Nikon Z DX 50-250mm f/4.5-6.3 VR
Fujifilm XC50-230mm f/4.5-6.7 OIS II, Fujifilm XC15-45mm f/3.5-5.6 OIS PZ
Fujifilm XF100-400mm f/4.5-5.6 R LM OIS WR, Fujifilm XF 18-135mm f/3.5-5.6 R LM OIS WR
Best Performing Fixed Aperture Lenses by Camera System
Canon EF-S 17-55mm f/2.8 IS USM Lens, Canon EF 24-105mm f/4L IS II USM Lens, Canon EF 24-70mm f/2.8L II USM Lens, Canon EF 24-105mm f/4L IS II USM Lens, Canon EF 24-70mm f/4L IS USM Lens
Canon RF 24-105mm f/4L IS USM, Canon RF 70-200mm f/2.8L IS USM, Canon RF 15-35mm f/2.8L IS USM, Canon RF 15-35mm f/2.8L IS USM, Canon RF 35mm f/1.8 IS Macro STM
Nikon AF-S Nikkor 70-200mm f/2.8E FL ED VR, Nikon AF-S NIKKOR 300mm f/4E PF ED VR, Nikon AF-S Nikkor 500mm f/4E FL ED VR, Nikon AF-S 105mm f/2.8G ED VR Micro, Nikon AF-S Nikkor 70-200mm f/4G ED VR, Nikon AF-S Nikkor 180-400mm f/4E TC1.4 FL ED, Nikon AF-S NIKKOR 400mm f/2.8E FL ED VR, Nikon AF-S Nikkor 300mm f/2.8G ED VRII, Nikon AF-S Nikkor 500mm f/5.6E PF ED VR, Nikon AF-S NIKKOR 28mm f/1.4E ED, Nikon AF-S Nikkor 35mm f/1.8GNikon AF-S, NIKKOR 24-70mm f/2.8E ED VR, Nikon AF-S NIKKOR 105mm f/1.4E ED, Nikon PC Nikkor 19mm f/4 E ED Tilt Shift Lens
Nikon Z 24-70mm f/4 S, Nikkor Z 24-70mm f/2.8 S, Nikon Z 14-30mm f/4 S, Nikon Z 70-200mm f/2.8 VR S, Nikkor Z 20mm f/1.8 S, Nikkor Z 24mm f/1.8 S, Nikkor Z 35mm f/1.8 S, Nikon Z 50mm f/1.8 S, Nikon Z 85mm f/1.8 S
Fujinon XC35mm F2
Fujifilm XF50-140mm, f/2.8 R LM OIS WR, Fujifilm 8-16mm f2.8 XF R LM WR Fujinon Lens, Fujifilm XF10-24mm f/4 R OIS, Fujifilm XF16-55mm f/2.8 R LM WR, Fujinon XF16-80mm F4 R OIS WR, Fujifilm XF16mm F2.8 R WR, LensFujifilm XF35mm f/1.4 R, Fujifilm XF56mm f/1.2 R APD, Fujinon 50mm f/2.0 XF R WR Lens, Fujifilm XF80mm f/2.8 R LM OIS WR Macro