What do you get when you mix an Australian space enthusiast and documentary maker with a British chemist and caver, a space cave science documentary apparently. For those of you who don’t know James, he’s an exchange student from Perth who runs a YouTube channel called Atomic Frontier. As for me, I’m a postgraduate chemical engineering student at the University of Leeds, who does a lot of caving and a bit of science. After hearing about the CHECC video competition we were both quite keen to make a video underground. 

This video was my first real attempt at filming underground, prior to this I had only taken photos. Cave photography isn’t easy, the environment is harsh and there is no ambient light. A standard camera sensor normally isn’t as sensitive as the human eye, therefore, you need quite a lot of light to get a decent photograph. This isn’t a bad thing though as having complete control over lighting allows you to take some pretty amazing photographs. To get the light I need I normally use flash guns, these provide orders of magnitude more light than standard torches which tend to produce narrow beams of low-medium intensity light.

The photo below was taken on an expedition in Austria, what you can see is a huge cave chamber discovered in 2016 called Galactica. The cave was so big most of it couldn’t be seen with normal lighting, however, with three flashguns it was possible to light the whole thing up quite nicely. Unfortunately, flashguns can only produce light for less than a second before requiring a short period of time to recharge themselves between flashes. So if we were going to get some good footage of larger chambers we were going to need some serious lighting, my first thought was to buy a big flood light off Amazon to take underground.

If there’s one thing my limited time as a scientist has taught me, it’s that the first time you try something even remotely difficult it goes horribly wrong. For this reason, I went caving specifically to find out all the things that could go wrong when filming underground. From this experience, we learnt a few important lessons…

  • It’s really hard to move and film underground at the same time.
  • Tripods are essential
  • More than one light source is better
  • Everything needs to stay still
  • Cave audio is terrible

If I was you I wouldn’t spend too much time watching this, just spend a few moments skipping through it to get an idea. Also, bear in mind this footage was distilled from an entire day of filming.

In the end, I decided to sack off the big flood light, it was too difficult to transport, delicate, not waterproof, only had one light setting and produced a beam of light so wide that I couldn’t effectively control the lighting at all. Fortunately, Haydon Saunders who I met on an expedition the previous year, let me borrow his bespoke floodlighting system for filming underground. This was great as we now had multiple sources of light which I could point in any direction and they were even rugged enough to be submerged under water.

The kit was very clever, despite the batteries looking like they should form part an explosive vest. These were homemade battery packs each made using four powerful ex-laptop 18650 lithium-ion cells taped together in series, the lamps 6 flood lights and 2 spotlights each produced 2000-3000 lumens of light. The two boxes you can see at the back were for charging, one of the boxes steps down the voltage from a DC power source, the other charges the batteries. The camera we were using was a Sony RX100 mk2 in waterproof dive housing, James kindly lent me his tripod.

At this point, I had a relatively good idea of what I needed to do to get some decent cave footage. Unfortunately, no matter how good my cave footage was, without a theme or narrative, no one would be interested in watching my videos. Fortunately, James was an ideal collaborator for the project. Not only did he have a great idea for the video, he was also an all in one presenter, scriptwriter and video editor. All I needed to do was navigate him to points in the cave that fit the script, set up the camera/lighting and make sure he didn’t die during filming.

The first scene took a while, about 40 minutes, 5 takes and 3 flood lights to be exact. Annoyingly, while filming the second scene our lights began to die, it turns out Haydon’s lights have a battery life of around 40 minutes each. Discovering this, a normal person would have either given up or decided to continue shooting without fancy lighting equipment. But we weren’t willing to compromise on quality, so we went back out of the cave to charge the batteries for a few hours before going back to continue filming in the evening.

After returning to the cave we wanted a shot of James abseiling, despite James having never abseiled in a cave before, he was keen to use a rope to descend down into the cave to get a better looking shot. After about 1-2 hours of filming the descent scene with multiple takes, we decided we should probably call it a day as Emma (our much-appreciated lighting assistant) looked like she was getting quite cold and bored.

At 6 am the next morning we got up for some mushroom and egg sandwiches before heading out to the cave. The day ahead was going to be challenging, we had 5 scenes left to film and only 6 batteries. The first few scenes went smoothly, some of the shots were photos I had taken in previous years just readapted for film. For one of the scenes we were quite lucky in that a bat flew into the shot just as I was panning, given the rarity of bats in Swildon’s this isn’t something anyone could have done on purpose.

One of the scenes involved James swimming through some constricted and flooded cave passage, luckily the first shot of James entering the passage went okay, so we didn’t have to re-shoot. However, upon swimming through the other side he accidentally left his light on, meaning we needed to retake the shot. Swimming through again I wasn’t quite happy with the way the shot turned out and so asked him to do it again, on the final run he managed to pull it off but did sound a tad hypothermic. For each shot he would have needed to have travelled to the other side before coming back through, meaning he swam through the passage a total of 8 times.

Now James was starting to look a bit like a tired drowned rat, despite this he was still determined to get all the remaining shots before leaving the cave, there’s a simple reason his videos are as good as they are, he just cares wayyy too much. As our last remaining battery was about to die we filmed the final shot and gladly headed out of the cave.

Now the cave footage had been shot our job was far from over, we still needed to get some thumbnail art, bake some cookies and film some scenes in a lab. James’s proposal for the lab scene was to demonstrate how water on Mars could be used to create a breathable atmosphere in a cave environment by separating it into oxygen and hydrogen using electrolysis, then he wanted to fill balloons with the gas we’d captured for an explosion scene demonstrating the potential application of the generated gas as a rocket fuel.

Depending on how you looked at it this proposal seemed fine, these were experiments carried out routinely in high schools around the world, we would only be producing a tiny amount of gas during the electrolysis, in combination the gases are explosive, but as they were being generated separately the risk of an explosion was very low. When we carried out a controlled explosion, I made sure the area surrounding the balloons was clear of any chemicals/equipment and put more air than hydrogen in the balloons to lower the energy of the explosion.

You could also say I was generating potentially explosive gasses in mostly glass apparatus by submerging live electrical cables into an electrolytic solution of water, then using these gasses for a controlled explosion within an industrial chemical research laboratory, which doesn’t sound as good for my job security.

After the lab scene was finished, we went to bake some cookies in order to explain planetary cooling, the idea being that planets/cookies with a larger surface area to volume ratio cool quickly relative to objects with a smaller surface area to volume ratio. Also, baking is fun.

Of course, no YouTube video would be complete without some cool thumbnail art to attract potential viewers. Having applied for a permit to visit one of Yorkshire’s most spectacular cave systems earlier in the week, I saw this as a great opportunity to get back to the familiar territory of cave photography.

Firstly, we tried to get a nice shot of the UKs largest cave chamber, complete with massive waterfall. The picture was okay but I couldn’t see it fitting with the video as none of the scenes involved a huge waterfall. So, we went hunting for another shot opportunity, fortunately, York university caving club were also in the cave at the time and had left a rope rigged on Flood entrance.

As it had been raining the night before, Flood pitch was quite wet. The rope had also been rigged away from the main spray of water meaning James could hang on the rope without being in the waterfall. After placing flashguns on a ledge behind James and climbing around the other side of a large hole I began to take photos. I probably took about 30 photos before deciding I probably had enough.

However, as a general rule the more cave photos you take the better they get, so we decided to keep going until my flash guns ran out of battery. I took about 15 more photos making small changes to my camera settings and flash positions, on the second to last shot before my flash guns died I captured what looked like green screen action hero movie art.

Later that week I got quite bored in a business innovation management lecture, so began editing the photo to make some movie promotion art for UKCaving. Using a program called GIMP I removed anything dark coloured from behind where James was abseiling, then replaced the background with a stock photo of space. I was going for a sort of Dr.Who/Cave/Space poster.

Having already invested an unreasonable amount of time working on the video we decided it wouldn’t be too much effort to do one more thing. Waking up at 6 am on a Saturday again, we headed out to valley entrance and Yordas Cave in the Yorkshire Dales. Going heavy on technology low on caving gear we set out to collect some more stock footage and authentic cave sound effects like dripping, running water, walking through a rocky streamway and waterfall sounds. We also planned to dub some of the cave footage.

Although we collected some good stock footage and cave sound effects, we also learnt a frustrating lesson about audio recording voices in a cave. The aim of recording in the cave was to acquire authentic sounding voice audio with real cave echo, unfortunately, there’s a reason recording studios are designed to avoid any reverberation. As well as making the presenter sound clearer, it also avoids the audio sounding choppy when it is cut together. With our audio, the echo from the previous clip didn’t carry forward into the second meaning the listener could tell when two separate pieces of echoey audio were cut together.

To help dub the scenes in sync with the videos, James had created a version of the cave video was every scene zoomed in on his face, unfortunately, water dripping from the ceiling onto James’s laptop caused the keyboard to break, a bitter end to an otherwise nice day.

After a night in a bag of rice the laptop started working again so luckily with 5 days to go before the deadline, we were back on track to finish the video, a decision was made to instead record the rest of the dubbed scenes in a professional recording studio using the ambient cave audio and real cave sound effects to enhance the videos audio quality.

Before the video was ready for screening, several hours were spent cutting the video together, making animations, syncing the audio and making colour/lighting corrections to each scene. But the hard work was worth it in the end as we won 1st place at the CHECC forum and we were very happy with the video.

When researching for the video James and I each independently came across this document, if you liked the video and want to find out more it’s a good read.