Feb 252013

Silt at the top of the Goat Track

About the site

Tank Cave consists of several miles of interlinking tunnels and passages north of Mt Gambier. The cave has shallow, clear water and changes character as you swim through the different tunnels and rooms. I suspect I’m now well past 25,000 photos in there and familiarity gives me a great opportunity to experiment.

Rocky tunnels in Tank

About the dive

With camera wrapped up and a mission in mind, Ken and I headed down the line, up the Goat Track and to the Elephant Room. We were trying a new strobe set up with an off camera strobe mounted on the top of each sidemount. This worked well through the restrictions, with Ken able to reach back and rearrange the strobes as required.

About the photo

The difficulty with cave photography is that it’s really dark. I think this leads to a tendency to blast out as much light as possible to try and light up the scene. If some of that light is coming from the camera the photos end up with a flat, harshly lit foreground that can detract from the middle-ground or distant subject.

It’s easy to see that adding off camera light increases the depth in the shot. The off camera light is by definition further away and so less of it reaches the camera. In smaller tunnels the walls also get in the way, leading to small hotspots rather than a wider lit area.

Ken brought his two strobes along for the ride and with lots of light available he hand held one as well as the two on his tanks. All these off camera strobes gave me the opportunity and incentive to turn down the on camera light, and focus on highlighting my model rather than a jumble of rocky foreground. The challenge was adjusting both light levels and positioning of my on camera strobe pair to gently put directional light (and therefore shadows) in the foreground. In addition I needed to get enough light on Ken’s new drysuit, usually in the centre of the photo, to show up the red. I have a lot of dud shots but I’m very happy with the ones that worked.

This top photo is also an example of shots of silt. I believe you can take great photos of silty water, but they need to happen from clear water looking into a defined silt cloud. The cheesy limestone at the top of this restriction explodes into the room at the slightest water movement, so by identifying my photo-taking location early and reaching it by circling the room I was able to maintain clear vis as Ken left the top of the restriction. You can see the trail I’ve left in the water that Ken is swimming through, following the line around.

  3 Responses to “Soft foreground lighting in Tank Cave”

Comments (2) Pingbacks (1)
  1. The gentle front fill looks good. A trick from when I was lighting stage shows is to use lights of slightly different colour to avoid that harsh flat light effect. If a couple of lights have very slightly different tints it creates a bit of contrast around shapes and makes a scene look 3D again.

    • Hmmm, interesting, thanks. I’ve seen people tinting strobes of different brands to get the light temperature all the same, but hadn’t considered reversing the process. I think bouncing light off different coloured wall rock might have done this incidentally in the past, with some caves looking “better” than others as a result.

 Leave a Reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>


(required, will not be displayed)