Wide Angle Showdown: Canon RF-S 10-18mm vs Tokina 10-17mm Underwater

By Douglas Klug
Images © Douglas Klug

For wide angle shooting, an underwater photographer wants a lens that can capture broad reef-scapes, close focus to fill the frame with smaller subjects, and show off the broad range of colors we get to experience in the underwater world.

Here’s some of the wide-angle work I put in with the Canon 10-18mm wide angle lens over the last few weeks. I loved how the lens let me get close enough to small objects that I could fill the frame and let all the colors through to the camera’s sensor.

 

Canon 10-18mm • 1/80 • f/11 • ISO 800 

 
The late summer and fall season is prime-time for wide angle underwater photography around the Channel Islands National Park in Southern California. As I dove my way into the seasons, I was thrilled to try out the new Canon RF-S 10-18mm F4.5-6.3 IS STM wide angle lens and compare it to the (now discontinued) Tokina 10-17mm wide angle lens that I’ve been shooting with for the last several years. I shoot on the APS-C sensor Canon EOS R7 camera inside an Ikelite Underwater Housing # 69746. With the Tokina lens, I use the Canon EF-R mount adaptor, but the Canon RF 10-18 is built for the R-mount cameras, so no adapter was required. I used the same dome port and housing while shooting both lenses. On the cropped APS-C sensor, the Tokina has an equivalent focal range of 16-27mm, while the Canon has an equivalent focal range of 16-29mm.

 

First Impressions

Out of the box, I immediately noticed the size difference between the two lenses. I had always considered the Tokina 10-17 to be a compact lens that traveled well, but the Canon 10-18 was noticeably smaller. Interestingly, the actual glass element of the Canon lens has roughly 30% smaller surface area than the Tokina.

At 2.72” (69mm) diameter, 1.77” (45mm) long, and only 5.28 oz (150g) the Canon RF-S 10-18mm is nearly about an inch shorter and a third of the weight compared to the Tokina 10-17mm.

The lens I used had an anti-reflection ring pre-installed. The Canon was not just smaller, but lighter, which might be a bonus for traveling divers.

Before taking the Canon lens underwater for the first time, I spent a bit of time learning how it performed by shooting the lens outside the housing. I found the minimum focus distance, a key point for shooting wide-angle underwater, was effectively the same as the Tokina. I found the auto-focus acquired focus-lock quickly and without hesitation, as long as I worked along contrasting parts of my subject.

Edge Sharpness

I was aware that there had been some concerns about the edge-sharpness of the Canon 10-18 when shot on crop sensor camera, so I wanted to put the lens through its paces to see if that was the case. After extensive shooting with the Tokina, I didn’t want to sacrifice any of the good experiences I’ve had with that lens.

I used the Canon lens in the same ways that I shoot the Tokina, shooting in manual mode with at speeds for 1/80th to 1/125th of a second at apertures from f/8 to f/18. To be certain about the edge sharpness, I did all my test shooting at the 10mm end of the lens, and shot through the DLM 6-inch Dome Port with Zoom for all my testing.

Canon 10-18mm: This image shot at 1/100 second and f/10 shows off the Canon 10-18’s ability to capture a reefscape with straight lines along the edges at the 10mm zoom position.

 

Tokina 10-17mm: This image shot at 1/100 second and f/11 with the Tokina 10-17 shows off the classic vignette created by the fisheye lens at the 10mm zoom position.

 

Rectilinear vs Fisheye

I found that the Canon lens performed differently than the Tokina I was used to, but in a good way. Like many long-time Tokina shooters, I was used to the pleasing vignette created by the Tokina lens when shot at 10mm. This subtle bending of the edges is considered a pleasing look to reef-scape and close-focus wide-angle shots taken with the Tokina lens.

The Canon lens behaved more like a rectilinear lens than a fisheye, with nearly straight lines, even at the edges. At the apertures I shot, the edges of the images were sharp. When I explored the question of the edge sharpness, I found that most of the concerns about edge sharpness came from shooters using the lens at lower apertures like f/4 or f/5.6. This is probably due to the narrower depth of field at those apertures. When shooting in the mid-range apertures between f/8 and f/16, I didn’t notice any degradation in sharpness.

Canon 10-18mm: This image shot at 1/80 second and f/13 shows off the Canon 10-18’s ability to capture the reefs colors in the 10mm zoom position.

 

Tokina 10-17mm: This image shot at 1/100 second and f/9 with the Tokina 10-17 shows off how the classic vignette helps with close-focus wide-angle.

 

Canon 10-18mm: This image shot at 1/100 second and f/11 with the Canon 10-18 at 10mm, shows some nice close-focus wide-angle vertical framing.

 

Tokina 10-17mm: This image shot at 1/80 second and f/8 with the Tokina 10-17 shows that classic vignette again, even with close-focus wide-angle.

 

Conclusion

Overall, I found the Canon 10-18mm to be a solid performer for underwater photography when paired with the APS-C sensor Canon R7, with the ability to let the shooter capture reefscapes, colorful scenes, and close-focus wide-angle subjects and turn them into beautiful images.

 

Additional Viewing

More Power, Smaller Package: Moving to Mirrorless with the Canon R7

Underwater Cathedrals: Shooting Magnificent Kelp Forests

Photographing Seals & Sea Lions Off the Southern California Coast

Bringing Out the Colors of Fiji: "Soft Coral Capital of the World"

Adapting Your Lighting Strategy Across Multiple Locations on the Trip-of-a-Lifetime

 

 

Douglas Klug has been diving California’s Channel Islands for over 30 years as a SCUBA diving instructor and underwater photographer in Santa Barbara, CA. Doug specializes in underwater photography within the kelp forest environment. His photo-essays have been published in print world-wide, including articles in California Diving News, DAN Alert Diver, and Dive Training. Doug’s images have been used in many publications and by the US National Park Service, US National Marine Sanctuary, the Monterey Bay Aquarium, Google, and Microsoft. Doug even does live talks on underwater photography for dive clubs and museums in Southern California. See more...