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Water Drop Collisions

Posted by Caz on Monday, 7th November 2011

After my recent success with the CameraAxe5 and the Microphone Sensor, I thought I would have a go at some shots using the Valve sensor today.

Here is the Camera Axe setup:

Valve Sensor Setup

Valve Sensor Setup

The valve sensor is plugged into Sensor Port 1 of the Camera Axe. It has the droplet size and delay controlled from the Valve Sensor Menu. The camera is plugged into Device Output 1 – using Bulb mode at f/11 and manual focus. The first flash is plugged into Device Output 2 and is set to go off after a short delay once the first or second drop has left the valve nozzle. The second flash is fired from the first via visual slave mode. Here are some setup shots:

General setup

General setup

Kitchen studio

Kitchen studio

Valve Sensor Details

Valve Sensor Details

Getting Started

First things first – you need to know rough timings for events with just ONE drop coming out of the valve sensor. For my first set of shots, I set Drop1 Size at 40(ms), Drop2 Size at 0 (ie no second drop) and varied the flash delay in 10ms increments between 200ms and 400ms to observe where the drops were during each time frame (dropping from a height of 330mm). The stop-motion animation on the right is composited from one frame taken at each flash time delay value.

This is an important step, otherwise you could be spending ages trying to catch the right moment via trial and error. If we use a bit of maths, however, we can get much nearer the predicted event straight away. There is more of an explanation at the excellent Camera Axe Valve Sensor tutorial page.

Valve Sensor Setup Menu

Valve Sensor Setup Menu

From the frames already taken, I decided that I wanted to have the 2-drop collision take place once the first drop was “on the rebound” and at the top of its “spout”. This gave me a delay value around 32oms. Looking at the motion to see where the second drop should be to collide with it, that gave a value around 230ms. The sums give us:

Pos1 (320ms) – Pos2 (23oms) – Drop1 size (40ms) = Drop2 Delay (50ms)

and

Pos1 (320ms) – Drop2 Delay (50ms) – Drop2 size (40ms) = Flash Delay (230ms)

So, plugging these values into the Valve Sensor Menu (see above) should get us in the right ballpark for a collision. I was desperate to try this out, but just as I’d got the vital numbers worked out, the rechargeable batteries in one of my flashes went flat! Since there was already a set on charge and no spares, I had to nip out to buy some disposables before I could give it a whirl. After taking one shot, I did a little bit of tweaking , as I noticed the flashes were going off a bit too soon for the interesting action. So I upped the flash delay to 245ms. And here we are – my first collision shot!

Valve Setup Menu: D1 (40), D2D (50), D2 (40), FD(245) ms

Valve Setup Menu: D1 (40), D2D (50), D2 (40), FD(245) ms

Getting Creative

Then it was time to play! Vary the delay and see what happens…

Oval Splash

Oval Splash

The Anti-Gravity Hat

The Anti-Gravity Hat

Mushroom And Raindrops

Mushroom And Raindrops

Tilted Sombrero

Tilted Sombrero

So that’s it for the moment. My favourite for the day was Frilly Skirt. I want to concentrate on some better lighting behind the splashes next time, but I need to wait for my new cable to arrive so I can run both flashes via the wireless TX unit. Then I can place them a lot further away from the CameraAxe electronics. But I’m pretty pleased with my first efforts at water splash collisions. Now that I’ve done a few shots, I should be able to get set up and running a lot quicker next time around.

5 Comments

  • […] several flat batteries later, I got there in the end. I was pretty pleased with my first efforts. How it was done. One Year Ago: Day #1042 Two Years Ago: Day #677 Three Years Ago: Day #312 This entry was posted […]

  • […] Contact ← Water Drop Collisions […]

  • […] the clever stuff. But actually, a lot of the time it was me pulling on this cable which made the Valve Thingy open and drop the drips. What a drip she is to think she can do it without my help! This entry was […]

  • […] softbox @ 1/128, timed with CameraAxe5 and Valve Sensor. Notes: One of my shots today from the water collision session. I thought this one looked great in mono – like someone reaching up out of the water. […]

  • […] might ask why I’ve bought this kit rather than using my Camera Axe system? One reason is the valves which came in the Camera Axe Valve sensor are very cheap – […]