Rectilinear and Fisheye Wide Angle Lenses Explained

Rectilinear and Fisheye Wide Angle Lenses Explained

Looking to capture a scene that spans beyond your normal lens? Or exaggerate the depth of your photo? It’s time to reach for a wide angle lens. Let’s explore why not all wide angle lenses are the same. When choosing a wide angle lens, one major factor to consider is whether it’s a rectilinear lens or a fisheye lens, also known as curvilinear.

What is a Wide Angle Lens?

A wide angle lens is a lens with a short focal length. A common way to classify a camera lens is by its field of view, which is determined by its focal length. While there’s not a single definition, on a full frame sensor, wide angle lenses generally have focal lengths smaller (wider) than 35mm. Normal lenses have focal lengths between 35mm and 70mm and telephoto lenses have focal lengths longer than 70mm.

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The Canon 24mm f/1.4L II lens is a high quality wide angle prime that corrects for distortion, making it ideal for landscapes and interiors.

Wide angle lenses may create some distortion, though different lenses result in different distortions.

The closer an object is to a viewer, the larger it will appear. If two objects are the same size, the one that is farther away will appear smaller. This is called perspective distortion and it’s why a straight road appears to converge to a point despite remaining the same width.

Wide angle lenses have a wide field of view, so you often have to position the subject or another focal point very close to the lens in order for it to fill enough of the frame. This exaggerates the difference in distance between multiple objects in the frame, resulting in significant amounts of perspective distortion.

Perspective distortion will be present in all wide angle lenses.

There’s another type of distortion that is common in wide angle lenses, which is where the edges of the image get bent, causing straight lines to appear curved. This is called barrel distortion and it’s more pronounced the wider a lens is. Ultrawide lenses with a focal length less than 20mm are at greatest risk of barrel distortion.

What is a Rectilinear Lens?

A rectilinear lens is made to reduce barrel distortion and the best lenses can virtually eliminate it even at very wide angles. If a little bit of barrel distortion does remain, image editing software can often correct it. The Canon 11-24mm f/4L and the Nikon 14-24mm f/2.8G are both fantastic rectilinear ultra-wide angle lenses. Canon has other great wide angle lens options.

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Taken at 12mm with the Nikon D610. See all of Nikon’s ultrawide lenses.

The majority of lenses made are rectilinear. They most accurately reflect the way that we view the world with our eyes. This makes them very versatile in a wide range of uses. As a general rule, unless you are specifically wanting to take advantage of distortion features, you should choose a rectilinear lens.

While barrel distortion is minimized or eliminated, photographers must still consider the perspective distortion that will occur with wide angle lenses. This makes them challenging to use with certain subjects. For example, filling up the frame of a wide angle lens with a person’s face will create unflattering distortions, particularly with the size of the nose.

Wide angle lenses are best in tight spaces where you want to get a lot of the surroundings in your shot. Architectural photographers shooting indoors should choose a rectilinear lens that will get most of the room in the frame while keeping walls, doors, windows, and other straight lines straight.

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Taken with a Canon 16-35mm f/4 IS lens at 16mm.

Similarly, photographers shooting urban environments and cityscapes should generally use a rectilinear wide angle lens. In most of these sorts of man-made environments, straight lines are everywhere and you generally want to avoid causing them to bend. Landscape photographers who shoot with wide angle lenses will also want to use rectilinear lenses to avoid unwanted distortion.

What is a Fisheye Lens?

A fisheye lens, also called a curvilinear lens, embraces barrel distortion and turns it from a flaw into a feature. Fisheye lenses are generally only found at the shortest focal lengths (typically less than 15mm) and create an almost circular image with a field of view that can reach 180 degrees. The Nikon 10.5mm f/2.8G and Canon 8-15mm f/2.8L are great choices for fisheye lenses.

Distortion and Fisheyes

The most obvious characteristic of a fisheye lens is how it will cause any straight lines near the edges of the frame to bend. Pictures taken with fisheye lenses often look like everything is getting pulled into the middle of the frame.

The level of distortion created by a fisheye lens is, in many cases, very unnatural and will detract from the scene (depending on your goals). However, there are times where fisheye lenses can perform the job far better than rectilinear lenses.

What Fisheyes are For

Fisheye lenses were originally created to photograph the sky and they still excel at that. You need to be careful with the horizon because if it appears near the edge of the frame it will have significant distortion. But if you are photographing only clouds or a starry night sky without any land, a curvilinear lens can squeeze far more into the image.

Similarly, fisheye lenses do a great job of capturing underwater scenes. Like photographing a sky, there are few straight lines underwater to show the distortion and you can fit more of the scene into the frame.

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Taken at 8mm. House your wide angle inside an AquaTech Underwater Housing unit.

Curvilinear lenses aren’t limited to scenes with empty space. Landscapes without straight lines can be shot with a fisheye lens if you put the horizon in the center of the frame. Similarly, you can shoot in a city if you’re careful to choose locations where you frame the shot with curved structures that hide the distortion.

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Taken with the Canon 8-15mm f/4L fisheye lens.

You can decide to embrace curvilinear lens distortion for certain effects. Shooting up or down tall buildings with a fisheye can create a feeling of vertigo. The curved edges of a frame can create a sense of motion in the right image. You can even use a fisheye lens to shoot a caricature portrait where the point is to create something comical.

Choose the Best Wide Angle Lens For Your Shot

Rectilinear lenses are more common and can be used in more situations than curvilinear lenses. But neither type of lens is inherently “better”. Which lens works best for you will depend on your own personal shooting style and subjects. You can always try and master both!

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