Fisheye Lenses vs. Wide-Angle Lens

What is a fisheye lens?

A fisheye lens is a special type of ultra-wide angle lens. They are small, ultra-wide, and show a distorted, spherical view of the world, most evident in the curved, outer corners of the photo.

Fisheye lenses happen to work very well underwater for a couple different reasons:

• They focus very closely
• There are few straight lines underwater
• Using a very wide lens allows to get very close to your subjects, giving your photograph more sharpness, and better colors when lit with a strobe.
• Behind a dome port, fisheye lenses perform better optically than regular wide-angle lenses.

The Sigma 8mm, 10mm, 15mm, Tokina 10-17mm, Nikon 10.5mm, Nikon 16mm, Olympus 8mm, Inon UFL-165 and the Canon 15mm are all "fisheye" lenses, these are extra-wide lenses with up to a 180 degree of view. Straight lines in the outer areas of the images will appear curved.

Tokina 10-17mm fisheye and Sigma 10-20mm comparison photos

Sigma 10-20mm at 10mm, this is not a fisheye lens.

Tokina 10-17mm fisheye lens, at 10mm. Note that the center of this photo is exactly the same as the Sigma 10-20mm photo, but as you move towards the edges this lens becomes "wider" and the subject smaller.

Sigma 10-20mm lens at 10mm

Tokina 10-17mm fisheye lens at 10mm, showing how the lines curve as you move away from the center

Photograph from a tokina 10-17mm fisheye lens underwater

Properties of fisheye lenses:

• They usually focus very close
• You can get very close to large subjects, maximizing color and sharpness
• They perform well behind dome ports with good corner sharpness, and they don't need a diopter
• When shooting ultra-wide angle, you benefit from a large depth of field
• They are small and light
• You usually need at least 2 strobes with good angle of coverage to properly light the entire area.

Nikon 10.5mm fisheye lens, and a tokina 10-17mm fisheye lens with the focus ring on it.

Fisheye lenses and focal length

Although people often think of a fisheye lens as wider than a rectilinear lens, it's important to note that at the same focal length, a subject at the center of a fisheye lens will be magnified the same amount as a rectilinear lens. This can be clearly seen in the example photos at the beginning of this article.

Barrel Distortion

When reading about fisheye and regular wide-angle lenses, you wil hear a term called barrel distortion. This distortion causes curved lines at the edges of the photo. This is a negative aspect of cheaper rectilinear wide-angle lenses at their widest settings. However, on fisheye lenses, this is their main feature. That is why they are called "fisheye" lenses, and the barrel distortion should not be viewed negatively.

Photo of oil rigs showing curved lines of the rigs structure from a fisheye lens.

Correction a fisheye lens in software

Land photographers will sometimes use software to correct the distortion of a fisheye lens. However, underwater this is rarely done, as the slight curvature of a fisheye lens is often considered a desired effect.

What is a rectilinear lens?

A rectilinear lens is any lens besides a fisheye, like a Nikon 12-24mm, Canon 10-22mm, Tokina 11-16mm, Tokina 12-24mm, Sigma 10-22mm, Olympus 9-18mm. Lines in photos taken by rectilinear lenses remain straight.

Inon and Ikelite make several "wet" wide-angle lenses for compact cameras, like the Inon UWL-100 and the UWL-105AD. Their width is usually expressed as an angle of view underwater. Read more here about wet lenses.

It is important to note the 17mm on a fisheye lens is not equivalent to 17mm on a rectilinear lens. For example, the Tokina 10-17mm at 17mm is about as wide as the Nikon 12-24mm lens at 12mm. In general, a fisheye will be much wider than a rectilinear lens. You can compare angle of views on my best lenses for underwater page. However, a subject in the center of a photo will appear similar size in a fisheye and rectilinear lens (e.g. - small subject taken in the center of a 10mm fisheye vs a 10mm rectilinear). The difference will be seen away from the center, and in the edges/corner of the photo.

A fisheye lens is good for

• Reef shots
• Getting really close
• Divers, models
• Large wrecks
• Mantas, whale sharks
• Schooling fish shots
• Over-under shots
• Sharks that come really close
• Close-focus wide angle of large macro subjects such as large frogfish, rhinopias, large seahorses

If a Manta ray or Whale shark comes close underwater, you'll want a fisheye lens to get it within the frame.

A rectilinear lens is good for

• Shots with straight lines where you don't want to see any curves
• Skittish pelagics, sharks, dolphins, that won't come close
• Reef shots that are easier to light the entire space
• Turtles, sea lions
• Many people use a rectilinear lens underwater, like a 10-22mm lens, because they also need a wide-angle lens for topside (out of the water) use, such as landscape photography, and they can't afford 2 wide-angle lenses. A fisheye lens has more limited use topside.

My recommended choice for underwater photograpy:

• Tokina 10-17mm fisheye lens

Angel shark in California, taken with my Tokina 10-17mm fisheye lens at 14mm. F13, 1/160th, ISO 160, strobes out wide. The shark was very close to me, maybe 2ft away. Shooting at F13 ensured a sharp photo in the corners.

Read my Tokina 10-17mm fisheye lens review

Micro-four thirds cameras

The Panasonic 8mm fisheye lens is an excellent choice for micro-four thirds cameras such as the Olympus E-PL1/E-PL2/E-PL3, or the Panasonic GF1/GF2.

Circular fisheye lenses

Cuttlefish, Sigma 8mm fisheye, film camera. F5.6, 1/30th. Photo by Uwe Schmolke.

The Sigma 8mm fisheye lens is a circular fisheye lens. Results are best on a full-frame dSLR camera, on a cropped-sensor dSLR the photo looks like this.

Sigma also makes the Sigma 4.5mm F2.8 circular fisheye lens for cropped sensor cameras. It has a 180 degree of view in all directions on a cropped-sensor camera. I'd love to try one out soon with my D300. 

Continue reading about Camera Lens Basics

Further Reading:

Best lenses for underwater use

Wide-angle underwater photography

Underwater composition

Strobe positions for underwater

Dome port optics

Tokina 10-17mm review

Where to Buy

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