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My favorite animal photographed with my favorite lens! This hand-sized blue-ringed octopus was a perfect subject for the OM System M.Zuiko 12–40mm f/2.8 Pro II lens behind a flat port
When one thinks of the first underwater optics to buy, the usua choices are a macro lens and a wide angle or a fisheye. Those two lens genres are popular for good reason, and there’s no doubt that the vast majority of underwater pictures are made with one or the other.
However, one of my favorite things about shooting with an Olympus or OM System Micro Four Thirds camera underwater is the incredible range of high-quality lenses available—beyond the typical fisheyes and macros. Of course, there is the spectacular Olympus M.Zuiko 8mm f/1.8 Pro Fisheye as well as the Olympus M.Zuiko 60mm f/2.8 Macro and OM System M.Zuiko 90mm f/3.5 Pro Macro. Also on offer are wide rectilinear zooms in the Olympus M.Zuiko 7–14mm f/2.8 Pro and the Olympus M.Zuiko 8–25mm f/4 Pro. Olympus/OM System users are truly spoiled for choice! Whether you’re into sweeping landscapes, tight macro work, or anything in-between, there’s a top-tier lens ready to meet your needs.
The wider end of the 12–40mm is perfect for larger subjects and semi-wide-angle images like this wonderpus from the Philippines
Despite the aforementioned wealth of great glass, the lens I find myself returning to time and time again for my underwater work is the Olympus M.Zuiko 12–40mm f/2.8 Pro—now updated as the OM System M.Zuiko 12–40mm f/2.8 Pro II.
Most OM System/Olympus shooters will already be familiar with the 12–40mm. It’s a cornerstone of the brand’s “Pro” trinity lineup: With a constant wide aperture of f/2.8, excellent sharpness, fast and accurate autofocus, and a very practical zoom range (equivalent to 24–80mm on full frame), it’s as close to a true all-rounder as you can get. Whether I’m shooting semi-wide scenes or dabbling in close-up and semi-macro work, this lens never fails to deliver. But that’s only part of why I love it.
When paired with a diopter, even classic macro subjects like the diminutive, but spectacular, harlequin shrimp, are on the menu for the 12–40mm. It’s wonderful to be able to photograph classic macro subjects and more classic wide-angle subjects on the same dive, with fantastic image quality
Thinking Outside the Port
I’ve always enjoyed exploring unconventional setups, especially for macro photography. While the 60mm macro lens is a solid performer, I often find it too limiting—especially in the waters of Victoria, where subject sizes can vary dramatically and good water clarity is far from guaranteed. The 40mm end of the 12–40mm is close to ideal for macro work, but using a dome port with this lens introduces challenges due to the increased field of view and awkward ergonomics for macro shots.
So, I decided to experiment. Rather than strictly following the manufacturer’s port charts, which I treat more as guidelines than hard rules, I mounted the 12–40mm behind a flat port with a 30mm extension ring—and what I discovered felt like striking gold. With this setup, I found a usable zoom range from 23mm to 40mm without significant vignetting (anything wider than 23mm does vignette). Add a diopter and flip adapter into the mix, and suddenly I had a compact macro powerhouse on my hands.
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My Isotta housing for the Olympus OM-D EM-1 Mark II rigged up with the OM System M.Zuiko 12–40mm Pro II lens behind a dome port (left) and behind a flat port with an additional diopter for extra magnification
The result? A 23–40mm macro-capable lens with the added reach and magnification of a diopter—effectively mimicking the field of view of a 60mm macro lens while maintaining the flexibility of a zoom. I’ve used this combination to shoot everything from seahorses to blue-ringed octopuses, shrimp, nudibranchs, Shaun the Sheep (Costasiella kuroshimae), and even pygmy seahorses. For me, it’s an unbeatable hybrid of optical excellence and creative versatility.
Gone are the days of taking only the 60mm and watching helplessly as a wonderpus swims past—knowing I won't be able to capture the full scene. What’s more, I haven’t noticed any drop in image quality; in fact, the opposite is true. Thanks to the bright f/2.8 aperture, I get sharper images, faster focusing, and a higher keeper rate compared to the dedicated 60mm macro lens.
Not even Shaun the Sheep, a sought-after and typically strictly super-macro subject, can escape my 12–40mm setup! Using a powerful diopter, even this diminutive sea slug is brought into sharp relief and fills plenty of the frame
The flexibility of the zoom range makes the 12–40mm a great choice for portraits of fish of all shapes and sizes. If it is a more skittish species like this thornback cowfish, simply zoom in to the long end!
Compatibility Caveat
It’s worth bearing in mind that this setup may not be universally compatible. I shoot with an Isotta housing and the H67 macro port, paired with a 30mm extension ring, and in this configuration, everything works beautifully (aside from the expected vignetting at the wider end). Results may vary depending on your housing and port system. It goes without saying, it’s always best to test your own setup before a major dive.
While I typically shoot the 12–40mm behind a flat port and sacrifice some of the versatility at the wide end, when conditions align and I have the proper subjects, like weedy seadragons, I’ll toss on a dome port and have full zoom range. The wider end is fantastic for wide-angle portraits of larger critters while also including a sunball
Why This Setup Works for Me
This lens and port combination turns one of the best all-around OM System/Olympus lenses into an extremely competent macro performer—without locking me into macro-only subjects. The excellent optical quality enables ultra-close focusing, while the wide aperture makes it possible to isolate subjects with soft, dreamy backgrounds. This combo has become my go-to setup for night dives and macro missions—so much so that my 60mm macro lens now sits on the shelf collecting dust. (Seriously, I might need a small excavation crew to find it!)
When conditions change—say, the sun’s out and larger subjects are active—I can switch to a dome port with a 40mm extension ring. This restores the lens’ full 12–40mm zoom range, perfect for mid-sized subjects or even close-focus wide-angle shots. The sharpness remains stellar across the frame, and I have the flexibility to zoom in for tighter compositions or zoom out for more context.
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Top: Shooting the 12–40mm behind a dome allowed me to not only fill a large portion of the frame with this stunning weedy seadragon, but also put it in context by showing its habitat. Bottom: Afterwards, I could zoom right in for a portrait of just the fish itself
Endless Possibilities
I’m certain that even more creative wet lens combinations are possible with this lens. For example, the Kraken KRL-09S wide angle conversion lens pairs with your 60mm macro lens to give you a whopping 154° field of view—allowing insane versatility, from semi-macro to ultra-wide angle. Similarly, pairing the 12–40mm with Nauticam’s wet optics or a compact 3–4-inch dome port could enable extremely intimate close-focus wide-angle perspectives.
For me, this kind of versatility is what makes underwater photography so exciting. The OM System M.Zuiko 12–40mm f/2.8 Pro II (or the Olympus original) isn’t just a general-purpose lens—it’s a creative tool that, when paired with the right gear and a bit of out-of-the-box thinking, becomes a powerhouse for almost any diving situation.
There is no optic I’d have rather had for this stunning pair of ornate ghost pipefish than my trusty 12–40mm Pro lens. The wider field of view while focusing closely is perfect for putting macro subjects into their environment without being a true wide-angle image
About the Author: Sam Glenn-Smith is an underwater photographer and scuba diving instructor based on the Mornington Peninsula, Australia. He specializes in macro and close-focus wide-angle photography, with a particular passion for octopuses. Sam is most well known for his stunning images of the southern blue-ringed octopus, one of the most beautiful and misunderstood species in the ocean. Sam has a broad range of photographic styles and interests, with a particular love for showcasing the weird and wonderful creatures that live mere meters below the surface at the piers of the Mornington Peninsula.
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