Nauticam MFO-3 Review: The Full-Frame Solution for Underwater Macro Photography

The rise of wet lenses for macro work has altered how we approach underwater macro photography. The majority of these lenses have been designed to increase apparent magnification by reducing the minimum focus distance of your camera's lens. These have been great for super macro photography, and as a result, ever smaller subjects have become popular to shoot.

However, with the rise of full-frame mirrorless cameras replacing DSLRs, there is an area of macro photography that has been sidelined—not through choice, but through a lack of options. All the major manufacturers have produced outstanding longer focal length macro lenses: the Sony 90mm, the Canon 100mm, and the Nikon 105mm. But no manufacturer has produced a high-quality 50mm or 60mm macro lens. These shorter macro lenses allow us to get closer to our subjects than the longer options, which is great for larger macro subjects where you want to have that wider field of view, and for poor visibility conditions where the water quality is a very limiting factor. With no apparent solutions coming from the big three camera producers, Nauticam has taken it on themselves to create a solution: the Nauticam MFO-3.

The Nauticam MFO-3 demands attention because it changes how you frame subjects and how close you can get without sacrificing image quality. This review looks at the technical design of the optic, what it does optically, how it performs in the water, and how it compares to the 90- and 100-millimeter macro options that many underwater shooters know well.

Why Wet Lenses for Macro Have Grown in Popularity

There are practical reasons behind the popularity of wet lenses. Wet lenses give flexibility. They allow you to convert a macro lens into something else, either with a wider field of view or, conversely, they allow you to push magnification further—and they give you this flexibility underwater. For underwater photographers, this translates into the ability to adapt to different subjects without changing the entire lens inside the housing. Wet lenses also reduce the need to carry multiple heavy macro lenses and ports on one trip. Adding or removing them underwater is straightforward compared with changing internal lenses inside a camera housing, which can only be done on the surface.

What the MFO3 Actually Is and What It Aims to Do Optically

At its simplest, the MFO-3 is a relay optic designed to sit in front of a macro lens and alter its optical character for underwater use. Nauticam describes it as a mid-range focus optimizer, and the design intent is clear. Rather than increasing magnification like a traditional diopter, the MFO-3 converts a long macro lens so that it delivers a wider field of view and a usable focus range that extends much further away from the port. Practically, this means a 90mm or 100mm macro paired with the MFO-3 will behave more like a shorter focal length macro in terms of field of view while still delivering large subject coverage and fine detail.

Nauticam states that the optic converts the lens field of view from roughly 23∘ to about 38∘ and that total magnification sits around 0.8 to 0.9 times when tested on 100mm and 105mm macro lenses. Now that all sounds a little complicated, but in basic terms, it converts your 90mm/100mm lens into something in the range of 50mm/60mm, allowing you to get much closer to the subject and still maintain the 1:1 characteristics of a true macro lens. It does all of this whilst also not affecting image quality, and in many cases, it actually improves image quality due to shooting through far less water.

How MFO-3 Differs from Previous Wet Macro Optics

Compared with earlier wet macro converters, the MFO-3 takes a different point on the optical trade-off curve. Nauticam’s prior SMC series focused on extreme magnification with very short working distances and aggressive optical compression. The MFO-3 moves away from that by targeting shooters who want more reach in practice and a broader field of view for larger subjects or for composing subjects in context. Where SMC optics often required the subject to be very close and were perfect for tiny critters at high magnification, the MFO-3 is tuned for a wider field of view, allowing you to get closer than before to your subjects and also to shoot subjects smaller in the frame without being too far away. This allows you to move away from close-up face portraits of subjects and start shooting them in their surroundings. The larger size and four-element, three-group construction are designed to preserve contrast and reduce aberrations across that extended working range.

Physical Build and Handling in the Field

The MFO-3 is a substantial piece of kit compared with small screw-in diopters. It has an aluminum body, an M67 filter thread to accept accessories, and a length that gives a useful balance point in hand. Out of the water, it weighs around six hundred grams, and in the water, its negative buoyancy is modest, which helps keep the front of the housing from wanting to flip forward. The optic is depth rated to recreational and technical limits that will satisfy most users, and the construction includes anti-reflection coatings on the glass surfaces.

For mounting it to the camera, it is important to have a good solution. These days, as macro shooters, we often have three different wet lenses with us at all times; therefore, I chose to go with the Nauticam bayonet mount as I can then easily switch them underwater. This solution works great for tropical water, for sure, but if I were doing a macro-heavy trip in a cold water environment, then I might choose to use a flip, even though I generally really dislike them as they just get in the way of everything. Also, for a cold water trip, the visibility is usually a little worse than on land, so I might just choose to have it on when I get in the water and use it as my primary lens and still use the bayonet system.

The lens also doesn’t have the usual 67mm thread on the front for adding an ND filter; instead, you need to buy an M82 filter holder for it. This frustrates me a little bit. I believe that for a $730 lens, this should come with it and not be an additional purchase. It also means you need to buy 82mm filters for the lens. I would like to use this lens for UV photography so I can be nice and close to the subject, but it is another purchase for the lens and adapter.

How It Performs Optically in Real Use

Specifications are one thing, and in-water performance is another. In testing across different environments, the MFO-3 delivers a consistent message. It preserves contrast well across the frame and keeps detail where other converters can soften edges. Color transmission is neutral thanks to the anti-reflection coatings, and there is no obvious color cast introduced by the optic. Sharpness at the center of the frame is impressive, and the edges remain usable at apertures commonly employed for macro work. I personally like to use a lot of open apertures in my macro work and enjoy the way the lens renders the out-of-focus parts of the frame; there are no bokeh issues created by the lens.

On full-frame and cropped sensors, the practical conversion provides an effective field of view that photographers describe as close to a 50mm to 60mm equivalent when mounted on a 100mm or 105mm macro lens. I really enjoyed using this to frame subjects more in their environment and also to get a little closer to the larger subjects but still be able to shoot them in their environment rather than just a close-up face portrait. The lens really allows you to get an extra dimension to your shooting.

Autofocus Behavior

One of the practical benefits reported with the MFO-3 is improved autofocus reliability at moderate distances. For me, the key to autofocus in macro photography is knowing how far away from the subject you should begin. By always bringing your camera up to your eye when you’re already in the sweet spot, autofocus will be quite easy.

Macro lenses by nature will always be slower than wide-angle lenses such as fisheye, but the autofocus with this lens is great. I paired it with the Sony 90mm lens, and it was a pleasure to shoot. I used it both in single spot focus and also in tracking spot, both on small and medium, and found both to be excellent. I have no reservations at all about the autofocus capabilities of the lens. I also used it on blackwater; the lens had no issues focusing, even on smaller subjects.

Practical Examples from Shoots

I adore shooting frogfish; they are one of my favorite subjects. But when you encounter larger ones with the Sony 90mm, you end up having to be quite some distance away even to just have a little bit of the environment in the frame. When you flip on the MFO-3, your field of view is transformed so much that you can actually start to shoot these larger subjects in their environment. It allows you to create more of a scene than the standard longer lens. It is great to have these different types of photos available to me now; with my previous camera (Canon 5D), I used to use the Canon 50mm for this, so it is great to have that option again.

I also really enjoyed using it on clownfish, especially in suboptimal visibility conditions. It allowed me to be nice and close to the larger ones, and the tracking focus worked great with these fast-moving subjects. It allowed me to shoot the anemone and have it as more like a close-focus wide-angle style shot.

Also, know that this lens isn’t for every subject. The 90mm lens suits a lot more macro subjects, so having the MFO-3 as a wet lens option that you can add underwater makes for a much more versatile set up.

Lighting with the MFO-3

The lens sticks out quite a lot from the front of your port, which works well for the lighting. It allows you to bring your strobes nice and close into the port if you wish and allows for pretty much any lighting technique you want. The lens really allows you a lot of flexibility with your positioning and in no way impedes you. Be aware, though, that if you have it on a flip, it could limit strobe positioning when not in use.

Who Benefits Most from Adding an MFO-3 to Their Kit

It’s quite simple: anyone who shoots the new mirrorless full-frame cameras. The lens works great with all of the best macro options for Sony, Canon, and Nikon and will add an extra dimension to your photos if you have these cameras. I really found it quite liberating after being locked into only my 90mm lens for the last few years. Early reports also confirm it works great with the new Sony 100mm lens also, which will soon make the Sony 90mm an antique.

Also, this is a great lens for anyone shooting these cameras in cold water or poor visibility environments. This will really help with your overall image quality as it allows you to be much closer and shoot through far less water than you currently can.

Practical Buying Advice and System Considerations

If you are considering an MFO-3, check your housing port threads and compatibility, because the optic uses standard M67 threads and integrates best with Nauticam ports and flip or bayonet systems. When buying this lens, you should really consider how you will mount it first.

As mentioned earlier, my preference is the bayonet mount. This lens is large, and having it on a flip doesn’t work for me, as then when you’re not using it, it has negative effects on strobe positioning. Also, I like to always have with me the MFO-1, the MFO-3, and a Kraken +6 diopter—three separate options—so I find it easier to have them on bayonet mounts in my pockets.

Conclusion

The Nauticam MFO-3 is a purpose-built, mid-range wet optic that gives photographers new ways to approach macro subjects. It bridges the gap between long macro lenses and shorter focal length options, reducing working range, widening the field of view, and delivering strong image quality with minimal aberration. For those who need versatility in their macro work, who shoot cold water, or who want to carry fewer lenses without losing creative options, the MFO-3 is a compelling tool. Add it to the kit not to replace your 90mm or 100mm lenses, but to complement them so you can shoot a wider range of subjects effectively and with confidence.

If you are interested in purchasing the MFO-3, consider using our Backscatter Photo & Video affliate link. The price is the same for you but Inside Scuba receives a small commission which we use to offset the cost of running the newsletter and keeping it ad free.