AOI UWL-09 Wide Angle Lens

AOI UWL-09 Wide Angle Lens


Buying our Sony RX100IV was a fabulous dive investment. We started to take advantage of it with our Meikon Wet Dome Port Lens, which gives back the field-of-view narrowed by the refraction of water.

But it was really in purchasing the AOI UWL-09 wide-angle lens that we started properly to take photographs underwater. (At least of non-macro subjects!)

Why a wide-angle lens? In free-diving, the subject matter is generally other divers, landscapes in the water column, or larger marine life—time being limited for the necessary waiting for macro subjects. So being able to control for zoom from wide-angle (close-up of large subjects) to narrow (smaller fish) is very useful. This isn’t possible with the Meikon due to the inability to zoom.

uwl09 Entering with the UWL-09 wide-angle lens.

What do I mean by wide-angle? Take, for example, a shot with the Sony in its Nauticam housing without a lens. This is in a swimming pool some 10 metres from the subject. Note the narrow field of view.

Original Photo taken in a swimming pool with just the Nauticam housing.

Now, take the same with a wide-angle lens. Note that I’ve left in the vignette of being fully zoomed out with a large aperture. (This doesn’t always appear, but when zoomed out to 24 mm, it does appear from time to time.) What a difference!

Wide-angle Same position but with UWL-09 wide-angle lens.

In general, the wide-angle is a very useful addition to our kit. It should be pointed out, however, that there is distortion at the edges—not just when zoomed out to 24 mm, but also when the f-stop is too low. When shooting with the UWL-09, I usually zoom in to 28 mm and make sure the f-stop is above 4.0.

There is a significant note to make regarding this lens. Contrary to what you read… you cannot assemble the lens outside of the water. It must be assembled in the water. The usual steps are (1) to assemble it, (2) enter the water, (3) disassemble, (4) wave away any bubbles on the lens or the housing, (5) reassemble.

If you do not do this, air will be trapped between the lens, and it will smear your photographs. If you do this, make very sure that the lens is attached before climbing into the water! I’ve made the mistake of cutting time by not attaching the lens all the way, as I knew I’d be reattaching it. The lens will unscrew if you hit the water hard.

AOI/Fantasea recently came out with a bayonet mounting to address this. The mount is attached to the wide-angle lens (this specific one!) such that it’s trivially easy to attach and detach the lens. AOI/Fantasea’s system is similar to the Nauticam bayonet mount, which was probably the inspiration. (See our article on the underwater housing for more.)

Geared up Female mount (screwed into lens port on left) and male wide-angle mount (right).

With the bayonet mount, I’m yet to lose a lens (or a fast-moving subject) whilst fumbling around to attach and reattach.


Great quality… I guess? I don’t claim to be able to evaluate lenses. A significant advantage over the Meikon is that the lens can handle zooming all the way through. I’m yet to notice any aberration except for blurring at the periphery, which isn’t a result of the lens, but often the simple fact of taking a wide-angle picture with too-low f-stop.


The detach-swish-reattach upon entering the water. This has cost me a lens before, as it requires jiggling the screws underwater. Especially when free-diving in current, this can be very challenging. (Plus, the sound it makes screwing it in…) The bayonet mounting system fixes this.

A pre-fitted buoyancy collar would also be a useful accessory, since the lens is quite heavy.