Deciding between a 50mm and a 40mm lens can feel a bit tricky, especially when you’re just starting out with photography. You see them recommended all the time, and they seem pretty similar, which can make choosing harder. But don’t worry!
It’s not as complicated as it sounds. We’re going to break down the 50mm vs 40mm lens difference in a really simple way, showing you exactly what each one does best so you can pick the right one for you. Let’s get started!
Understanding Focal Length
Before we get into the specifics of 50mm versus 40mm, it’s good to know what focal length actually means. Think of focal length as the “eye” of your lens. It’s measured in millimeters (mm) and tells you how much of a scene the lens can capture and how magnified the subject will appear.
A shorter focal length, like 20mm or 24mm, gives you a wide-angle view. This means you can fit a lot into your photo, like landscapes or large groups of people indoors. A longer focal length, like 200mm or 300mm, is like a zoom lens, bringing distant subjects much closer.
Lenses around the 50mm mark are often called “normal” lenses because their field of view is similar to what the human eye sees without much distortion. This makes them feel very natural to use.
The 50mm Lens A Classic Choice
The 50mm lens is a legendary piece of gear for photographers of all levels. It’s often celebrated for its versatility and the way it renders images.
What Makes 50mm Special
The primary reason the 50mm lens is so popular is its ability to mimic the human perspective. When you look at something through a 50mm lens, it generally appears the way you would see it with your own eyes, without making the scene look wider or narrower than it really is.
This natural perspective makes it a fantastic all-around lens. You can use it for:
- Portraits: It creates a pleasing compression of features, making people look good without distorting their faces.
- Street Photography: It’s wide enough to capture a scene but not so wide that you lose your subject.
- Everyday Shots: From your pet to a coffee cup, it captures scenes faithfully.
- Low Light: Many 50mm lenses have wide apertures (like f/1.8 or f/1.4), allowing them to gather more light. This is great for shooting in dim conditions and for creating a beautiful blurred background (bokeh).
The Look of a 50mm Lens
A 50mm lens offers a wonderful balance. It’s not so wide that it exaggerates perspective and makes things look distant, and it’s not so long that it requires you to be far away from your subject. This makes it incredibly comfortable to use in various situations.
The background blur, or bokeh, that a 50mm lens can produce is often very smooth and pleasing, helping your subject stand out. This is particularly true with faster lenses that have wider maximum apertures.
The 40mm Lens A Slightly Wider View
Now let’s talk about the 40mm lens. It sits in a very interesting spot, offering a perspective that’s a little wider than the classic 50mm, but still close enough to feel natural.
What You Get with a 40mm Lens
A 40mm lens provides a slightly wider field of view compared to a 50mm. This difference might seem small, but it can be quite significant in certain photographic scenarios.
The extra width can be very helpful for:
- Environmental Portraits: You can include more of the subject’s surroundings, telling a richer story about who they are or where they are.
- Group Photos: Fitting more people into the frame, especially in tighter spaces, becomes easier.
- Interior Shots: When you can’t step back far enough, the 40mm gives you a bit more breathing room to capture the scene.
- General Purpose: It’s still a fantastic “walk-around” lens that can handle a variety of subjects.
The Feel of a 40mm Lens
Using a 40mm lens feels very similar to a 50mm in terms of how you frame your shots. You don’t have to move your feet as much to get more into the picture. It’s a comfortable focal length for many people, especially those who naturally tend to capture slightly wider scenes.
The compression and bokeh produced by a 40mm lens will be a bit less pronounced than with a 50mm lens, assuming similar aperture values. This can sometimes be seen as a benefit if you prefer a more natural depth of field or want to keep more elements in focus.
Key Differences and When to Choose
The core difference between a 50mm and a 40mm lens boils down to their field of view and how they affect the final image. Let’s compare them directly.
Field of View Comparison
Imagine you’re standing in the same spot, taking a picture with both lenses.
- The 50mm lens will capture a slightly narrower slice of the scene.
- The 40mm lens will capture a slightly wider slice of the scene.
This means if you’re trying to fit more into your frame, the 40mm has a slight advantage. If you want to isolate your subject more and get that classic, slightly compressed look with more background blur, the 50mm might be your preference.
Depth of Field and Bokeh
Depth of field refers to how much of your image is in focus, from foreground to background. Bokeh is the aesthetic quality of the blur in the out-of-focus parts of an image.
Generally, longer focal lengths (like 50mm) produce a shallower depth of field and more pronounced bokeh than shorter focal lengths (like 40mm), assuming you’re shooting at the same aperture and the same distance from your subject.
This means a 50mm lens at f/1.8 will typically give you a more blurred background than a 40mm lens at f/1.8 when shooting the same subject from the same distance. For portraits where you want to make the person pop against a soft background, the 50mm often has an edge.
Perspective Compression
Perspective compression is how a lens makes objects appear closer together or farther apart than they actually are. Longer focal lengths tend to compress perspective more, making distant objects seem closer to the foreground objects.
A 50mm lens offers more perspective compression than a 40mm lens. This is why 50mm lenses are often favored for portraits to create a flattering look, avoiding the slight distortion that wider lenses can sometimes introduce.
When to Choose 50mm
You might lean towards a 50mm lens if:
- You love classic portraiture and want that signature background blur.
- You prefer a focal length that closely matches human vision for a natural feel.
- You shoot in a lot of lower light conditions and want to maximize light gathering with a wide aperture.
- You want a lens that helps you isolate your subject beautifully.
When to Choose 40mm
You might find a 40mm lens more appealing if:
- You often shoot in tighter spaces and need that extra bit of width.
- You enjoy environmental portraits where the background tells part of the story.
- You want a lens that’s great for general use but offers a slightly wider perspective than a 50mm.
- You like a natural look but want to include a little more context in your shots.
Choosing the Right Lens for Your Camera
Both 50mm and 40mm lenses are excellent choices, and the “better” lens really depends on your personal shooting style and what you aim to capture.
Prime Lenses vs. Zoom Lenses
It’s important to remember that both 50mm and 40mm are common focal lengths for prime lenses. Prime lenses have a fixed focal length, meaning they don’t zoom. This often results in sharper images and wider apertures compared to zoom lenses.
Zoom lenses, on the other hand, offer a range of focal lengths (e.g., 24-70mm). While convenient, they usually don’t offer the same extreme low-light capabilities or the same level of background blur as a dedicated prime lens at 40mm or 50mm.
Crop Sensor Cameras vs. Full-Frame Cameras
The effective focal length of a lens changes depending on your camera’s sensor size. This is known as the “crop factor.”
On a full-frame camera, a 50mm lens is a 50mm lens, and a 40mm lens is a 40mm lens.
On a camera with a crop sensor (like APS-C, which has a crop factor of around 1.5x or 1.6x), the field of view becomes narrower. So, a 50mm lens on an APS-C camera will behave more like a 75mm or 80mm lens on a full-frame camera. Similarly, a 40mm lens on an APS-C camera will act more like a 60mm or 64mm lens.
If you have a crop sensor camera:
- A 50mm lens might feel a bit too long for everyday walk-around use and is often better suited for tighter shots or portraits.
- A 40mm lens on a crop sensor often gives you a field of view that is very close to a 50mm on a full-frame camera, making it a great “normal” lens equivalent.
When considering your purchase, always check how the focal length will translate to your specific camera body.
Lens Mounts and Compatibility
Make sure the lens you choose is compatible with your camera’s mount. Different camera brands (Canon, Nikon, Sony, Fujifilm, etc.) use different lens mounts, and lenses are not always cross-compatible without an adapter.
Always check the specifications to ensure the lens will physically fit and function correctly on your camera.
Hands-On Experience The Best Teacher
Ultimately, the best way to decide between a 50mm and a 40mm lens is to try them out if you can. Renting them or borrowing them from a friend can give you a real feel for how they perform in your hands.
Consider the types of photos you take most often. If you’re constantly wishing you could fit a bit more into your frame without stepping back, the 40mm might win. If you love the way a 50mm isolates subjects and creates creamy bokeh, that’s your signal.
Frequently Asked Questions
Question: Is a 50mm lens good for beginners?
Answer: Yes, a 50mm lens is often considered an excellent starting point for beginners. Its “normal” field of view is intuitive, and many affordable 50mm lenses offer great image quality and wide apertures.
Question: Will a 40mm lens be too wide for portraits?
Answer: No, a 40mm lens is not typically too wide for portraits. It offers a slightly wider perspective than a 50mm, which can be great for environmental portraits or including more of the scene, but it still avoids the extreme distortion of true wide-angle lenses.
Question: What’s the difference in bokeh between a 50mm and 40mm lens?
Answer: Generally, a 50mm lens will produce more pronounced background blur (bokeh) than a 40mm lens when shooting at the same aperture and distance from your subject, due to its longer focal length.
Question: Which lens is better for street photography 50mm or 40mm?
Answer: Both are great for street photography. The 50mm offers a classic, slightly compressed view, while the 40mm gives you a bit more room to capture the scene without moving your feet as much, making it useful for wider street shots.
Question: Does the crop factor affect the 50mm vs 40mm lens choice?
Answer: Yes, the crop factor significantly affects the effective field of view. On a crop sensor camera, a 50mm lens acts like a longer lens, and a 40mm lens might offer a field of view closer to a 50mm on a full-frame camera, making it a popular choice for crop sensors.
Final Thoughts
Deciding between a 50mm and a 40mm lens comes down to what feels right for your creative vision and how you like to compose your shots. The 50mm lens is a timeless classic, providing a perspective very close to human vision and excelling at isolating subjects with beautiful background blur, making it ideal for portraits and general use where you want a natural look. On the other hand, the 40mm lens offers a touch more width, which can be incredibly useful when you need to capture more of your surroundings without stepping back, perfect for environmental portraits, tighter spaces, or when you want to include more context in your images.
Both focal lengths are fantastic for everyday shooting and can deliver stunning results. Consider your camera’s sensor size as it will alter the effective field of view, potentially making a 40mm on a crop sensor feel like a standard 50mm on a full-frame. Whichever you choose, both lenses will serve you well and help you grow as a photographer.
Experiment, see what speaks to you, and happy shooting!
