A manta ray glides gracefully underwater, surrounded by deep blue ocean. Sunlight filters through the water, illuminating its wings.

31 jul 2025

Diving with the TAMRON 20–40mm – A Hands-On Experience

Stories

Diving with the Tamron 20–40mm – A Hands-On Experience

By Stefan Tschumi

My passion for photography began in 2008, sparked by a formative encounter with the Dalai Lama’s official photographer during my university studies. Since then, photography has never let go of me. Today, I work as a freelance photographer and videographer, taking on projects for TV productions and universities, where I also teach photography and video. I’m often on the road for assignments – sometimes for weeks at a time. Last year, I spent two months in Namibia creating video portraits for a hotel chain. I also spent time on the Galápagos Islands working on a magazine story, and documented whale sharks and giant mantas in the Maldives. For me, photography and video go hand in hand – they complement each other perfectly.

A manta ray glides through the clear blue waters of the ocean.

Zooming Underwater? Finally Possible!

The idea to use the TAMRON 20–40mm underwater came about spontaneously. I’ve done quite a few dives before, but almost always with prime lenses. Zoom lenses are usually tricky underwater because they’re often too large to fit in standard underwater housings.

A manta ray glides through the clear blue waters of the ocean.

That wasn’t the case with the 20–40mm. The lens is super compact and worked beautifully even inside the housing. I was able to zoom and manually focus underwater using external control wheels and focus rings. That was a huge plus, as I wasn’t limited to just one focal length. With a prime lens – say, a 16mm – you’re locked in. Now I had the flexibility to zoom in when needed, and that made a big difference. It was genuinely fun to work with.

Whale shark swimming over a coral reef, its body covered with white spots, in deep blue ocean water.

On Location: Switzerland, Maldives, Galápagos

I took the lens along on several assignments, including a shoot with Maja Homberger, a pioneer in Swiss tourism – which also involved underwater shots. After that, I headed to the Maldives, where I focused on photographing giant mantas and other marine life. Being able to adapt quickly to different situations was a real advantage.

A manta ray glides gracefully underwater with its wings outstretched. The sunlight penetrates the water and casts a calm blue glow.

I used the TAMRON 20–40mm on the Sony A1 – and the autofocus worked flawlessly underwater. While manual focus is also possible, the fast and precise autofocus made things much easier. Underwater, I usually rely on wide-angle lenses, since larger lenses don’t fit into the housings. But with the 20–40mm focal length, I suddenly had creative flexibility I’d never had underwater before.

Of course, the lens isn’t just suited for underwater use. It’s also a great option for landscape photography or video work with a gimbal. In Morocco, for example, I used it as a secondary lens alongside the 35–150mm F/2–2.8 Di III VXD. Especially when mounted on a gimbal, the 20–40mm shines: it’s well balanced and barely extends when zooming, making for stable, uninterrupted shots.

My Conclusion

Whether in Switzerland, the Galápagos, or the Maldives – the 20–40mm was a consistently reliable companion. Underwater, its compact build and flexible focal range opened up entirely new creative possibilities. And on land – during travels or video productions – it has become a regular part of my gear, thanks to its strong image quality and ease of use.

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