Rectilinear vs Fisheye Lenses for Underwater Wide Angle Photography [VIDEO]

A good wide angle lens is essential in underwater photography and videography. Wide angle lenses allow you to reduce the amount of water between you and your subject, increasing color and clarity in the resulting image.

But not all wide angle lenses are created equal! Ikelite Photo Guru Steve Miller walks you through the differences between rectilinear and fisheye lenses and how those differences will impact your underwater photography. Scroll down to read the full transcript.

Why Use a Fisheye Lens

What's better for underwater, a rectilinear lens or a fisheye lens? I've shot over a hundred different lenses underwater over the years, and for me 90% of the time I would go with the fisheye lens. Let's talk about why.

Now fisheye lenses are a specialty lens for topside photography, but they're almost a standard lens for underwater photography. Some of the reasons for this is that the fisheye lens allows you to get super close to your subject. You could even say that it forces you to get close to your subject because the focal length is so wide on the fisheye lens that if you're not close, your subject will be very small in the frame.

Now, we love super wide images underwater. It allows us to not just get a picture of a beautiful animal or a fish or a model or even a shipwreck, but it'll also allows us to incorporate the environment into the images. You could get clouds, sun ball, maybe a silhouette of the boat or even a silhouette of your buddy.

For this kind of imagery, we like the widest possible focal length. Image taken with the Canon 8-15mm f/4L EF USM fisheye lens. © Steve Miller

Fisheye vs. Rectilinear Lenses

When you go to select your super wide lens, you can have a choice between fisheye and rectilinear. For me, the choice will almost always be fisheye. I find that the fisheye lenses will focus faster than rectilinear. I also find they're a little sharper behind dome ports than a rectilinear lens. But most importantly, the fisheye lens is going to give me a wider frame. So I'm going to be able to cram more of the dive site and get more subjects into the lens than with a rectilinear.

I also find that for over-unders, the fisheye lens does a little better job of keeping both the top and the bottom sections of the frame sharp and in focus.

Pro-tip: stopping down for split shots is always good practice. Image taken with the Tokina 10-17mm f/3.5-4.5 fisheye lens © Steve Miller

Rectilinear Lenses Underwater

If you're a topside photographer, you might already own rectilinear super wide lens. These will work fine, but if you put it behind a dome port, I think you might find that your corners and your edges lack a little bit of the sharpness that you can get with this lens topside. Also, you may find that it focuses a little bit slower behind a dome port than it does topside. And then lastly, if you shoot over-unders, you may find that it's a little harder to keep both the under section and the over section in sharp focus at the same time and this is due to the inherent depth of field that we have.

Rectilinear Lenses Underwater

I know a lot of underwater photographers that specialize in big animals, and many of them will prefer a rectilinear lens. The rectilinear lens will tend to distort less than the fisheye lens.

If you're trying to get the truest shapes and forms of big animals, the rectilinear lens will do a better job of this because you're going to have less distortion. Taken with the Sigma 24-70 F/2.8 rectilinear lens. © Logan Wood

Big Animal Photography with a Fisheye Lens

If you want to minimize the distortion that's produced by a fisheye lens, couple of things you can do is think about the angle that your subject is coming into the frame and remember that the distortion will be worse around the edges. So anything that's in the middle of your frame with a fisheye lens will be very, very sharp but if you continue that same shape into the corners and the edges, that's when you're going to notice a little bit of stretch and a little bit of distortion.

Prime vs. Zoom Lenses

Whether you choose a fisheye lens or a rectilinear lens, you'll also have a choice as to whether you buy a prime lens, which is a fixed focal length or a zoom. Now, there used to be a lot of discussion about how prime lenses are so much sharper than wide angle zooms or just primes versus zooms in general because the focal length is variable. I think this is almost a moot point these days. The wide angle zooms that are out today are very sharp, very crisp. Is the prime lens going to be sharper? Probably. Will you be able to see this and find this in your images? I never have.

Additional Reading

Why You Need a Fisheye Lens Underwater

Circular Fisheye Showdown: Canon 8-15mm vs Olympus FCON-T02

Tips for Shooting Split Shots with Your Underwater Housing [VIDEO]

The Best Canon RF-Mount Lenses for DLM Underwater Housings 

The Best Canon RF-Mount Lenses for DL Underwater Housings [VIDEO]

Nikon 8-15mm Fisheye Lens Underwater Photography Review

Wide Angle Fisheye to Macro on the Same Dive with FCON-T02 Lens

Ambassador Steve Miller has been a passionate teacher of underwater photography since 1980. In addition to creating aspirational photos as an ambassador, he leads the Ikelite Photo School, conducts equipment testing, contributes content and photography, represents us at dive shows and events, provides one-on-one photo advice to customers, and participates in product research and development. Steve also works as a Guest Experience Manager for the Wakatobi Dive Resort in Indonesia. In his "free" time he busies himself tweaking his very own Backyard Underwater Photo Studio which he's built for testing equipment and techniques. Read more...