Mar 252013

Lake Ayre, Tank Cave gold line

About the cave

The photo above was taken under “Lake Ayre”, which is on the gold line in Tank Cave. Given its convenient location I usually swim under it at least once on a weekend in Tank, on the way home from the further reaches of the cave. It’s a completely enclosed air space composed of bubbles exhaled by passing divers. When first approached from back in the tunnel, you can look up and see the still, mirrored surface. Once divers swim underneath and exhale the ripples begin, spreading outwards to the walls on either side.

Ken under Lake Ayre

About the shot

As I was putting together my talk for OZTeK last weekend I spent a lot of time trawling back through my archives of underwater photos. Looking at the last three years with my current camera, I can see a few different phases. There’s definitely been a period in the last six months where I loved taking shots of divers silhouetted sideways against the light, and one before that where almost every shot I took was in portrait orientation. Sometimes these were related to the caves I was diving – portrait orientation photos work really well in sinkholes with big sunbeams coming down from above.

I’ve had the opportunity to dive in a few caves with huge air-water interfaces beyond the grotty entrance pool. There are no wind, waves or weather to ruffle the water’s surface underground, and looking up from underneath is like looking at a giant mirror.

The challenge

Reflective surfaces aren’t the easiest thing to capture. As well as the aforementioned issues with bubbles creating ripples, getting the subject in the right place to see both your buddy and their reflection in the photo can be tricky. If the diver is more than a couple of metres down their reflection will be a long way in front of them. The easiest thing to do is ask them to rise up as closely as possibly to the surface, bringing their reflection right in above them.

Lighting is also difficult – strobes pointed up at the lake above will reflect down, but a lot of the light will be lost to the cave above instead of lighting the picture. Light from the diver needs to hit the surface to create their reflection and then hit the camera, and I’ve taken underexposed images of Lake Ayre more times than I can count. It doesn’t help that the strobes are normally going flat by the time I swim back through here!

In the photo above, Ken has a strobe placed on each of his tanks, and another in his hand. The three strobes off camera are providing a nice even light behind him, which means I could reduce the power of the on camera lighting. As he’s still back in the tunnel rather than under the Lake, the ring of light extends to the white limestone over his head. As he moved forward under the Lake that lighting was lost and the images got a lot darker – see the second photo. Even though those off camera strobes are now a lot closer the camera, there’s not much for the light to bounce off.

So why mention this now? By the time you read this I will be underground in Weebubbie Cave, Western Australia. Weebubbie has a wide, white limestone tunnel and crystal clear water and I can’t wait to take photos in there. But I reckon some of the best images to be had in the cave are in the “entrance”, a 150m/500ft long lake from the gearing up spot to the start of the tunnel. The entrance lake is up to 20m/60ft deep, and well inside the dark zone of the dry cave. It’s a fantastic place to do deco, scootering laps between the massive, car-sized limestone blocks that poke up from the bottom.

I think that we’ve all been a bit focussed on diving the tunnel, and if this huge lake was at the end of the tunnel instead of the beginning it might get a bit more attention. By this time next week I hope to have created some fantastic photos under this massive mirror. Until then, check out the quick shots I got from our November trip with ABC’s Catalyst – the entrance lake here, and the tunnel shots here.

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