Do you want to capture a water drop? Then you're right here. With a little bit of effort you can get good pictures of falling and splashing water drops! I tried to explain every step as good as possible to get perfect results in the end. I want to show you how I captures a water drop using a standalone Arduino board (no computer is used).
The idea is based on the simple version with the difference, that no PC is used anymore. All parameters are set directly on the device.
The picture above was made with the help of a flash (Yongnuo YN-560 IV).
Here are more parts needes than in the simple version. Especially the small display is important, because you need it to change the parameters. I used the following parts:
|4||Resistor||10kΩ||Für die Buttons|
|1||Resistor||220Ω||For the LED|
|1||Camera connector||Is explained later|
The wiring has to be done like the picture below shows it. The advantage of the Arduino Nano is that you can put it directly onto the breadboard. This makes everything neat and comprehensible. The 4 pushbuttons are places so, that they have from left to right the following function: Ok, Cancel, Left, Right. The sensor is connected later, because I will present two different types of sensors.
The shematic plan shall clear everything. The components 'camera', 'sensor' and 'display' are explained later.
Note: The one who owns an Arduino Uno (and wants to use it) has luck, because the pinout is the same on the Uno and Nano, because both are using the same processor (ATmega328).
The camera connector is a simple 3.5mm stereo jack. Many cameras and flashe support these. To built the connection you need a handful of parts:
The wiring between optocoupler and 3.5mm jack must be designed, that the housing (SLEEVE) of the connector is connected with the emitter of the optocoupleer. The optocoupler's emitter must be soldered with the Left-Pin (trigger). With the Right-Pin the camera's focus is enabled, but that's not relevant here.
Pin 1 on the optocoupler is the anode (+), pin 2 is the cathode (-). When someone asks, why I'm using an optocoupler: Keeps you from frying your stuff!
If you use the digitalWrite() command on your Arduino it generates a voltage of +5V on the pin. This could harm your camera. To be safe we're using an optocoupler. It's function is comparable with a relais, but the switching time is much shorter. If you're unsure about the coupler's pinout, please refer to the datasheet.
I've two different sensors to choose. The first one is the same as in the Water Drop (Simple) project: A photocell. It's built with an infrared LED and a phototransistor. Both elements have to face each other. The distance between them is about 15 to 20 millimeter, so the LED illuminates the transistor. You need 4 parts:
|1||Resistor||220Ω||For the IR-LED|
"Sensor Jack" is the connection between the sensor and the breadboard. It can be done with 5 cables - actually with 4 if you bunch both ground cables together. The fastest and cheapes method to built the sensor is by using block clamps. That works better than you might think.
The second variant is more advanced. I purchased a reflex light scanner which provides a digital output signal. I took care, that the signal goes low, if an object is recognized infront of the sensor. That way you can interchange both sensors without changing the code.
The sensor's positon is infront of the water drop. That needs patience, because it needs some time until you've found the perfect distance between the sensor and the drop. The connection is exactly the same as of the first sensor: +5V, Signal und Ground. The two cables for the IR-LED are left out. Be sure that your sensor is built for a +5V supply!
The display is a 0,96" OLED, which communicates with the I²C bus. The Arduino supports it if you add the Wire.h library. Then both pins, A4 and A5 are reserved for the bus and can't be used for any other tasks. The pinout:
To get text on your display you need this library.
As podium for the drop I'm using a kind of table, which you can built fast and cheap by your own. The table's leg size is 40x20mm, it's lenght is 700mm. The connection wood is 500mm long. I placed a rack on top of it which is moveable in one direction.
The drop itself is created with a syringe. To not wiggle the frame I use a thin hosepipe, which ends up in a nozzle. You don't have to make the nozzle on a lathe, but if you like to:
The nozzle is mounted with a M8 hexagon nut. The hose is then pulled over the nozzle.
It's not pretty, but it does its job.
In it there is a short breadboard on which the components are placed. On the right side (not seen in this view) there is a 12V power supply jack that's connected with the Arduino's Vin and GND pins. On the left side there is a small pocket for the USB connector.
How could it be different - GitHub!
The main part of the code is the menu, if anybody is interested in menu-coding, here's my example. Of course, there may be better ways to create a menu like this.
Now I show some details to the 'trigger code'. When you start the process the controller calculates out of the given parameters the time that passes by from the moment the water drop falls through the sensor and hits the water's surface. This time can be varied with an additional delay.
At the beginning of the process the sensor's value is sampled. This is used as a reference for the drop. If it falls through the sensor that new value is lower than the reference. The calculation of the falling time is done with the following formula:
The formula was created out of the simple connexion Speed = Way / Time. I just added the height before the sensor. The terms ha[m] and hu[m] are the heights, the parameter g[m/s²] is the gravity.
Is the code loaded on the Arduino and are sensor and camera connected with it, it can be used standalone. It just needs a power supply. You can use an USB battery pack, they are cheap and easy to use, but you can also use any 12V power supply on the Arduinos Vin pin.
Via the menu you have to set all parameters, therefor use the 4 buttons. OK and Cancel are changing their behaviour depending in which state the menu is:
- OK enter the selected value.
- Cancel changes the times sign.
- OK is used as Right.
- Cancel is used as Left.
The changeable parameters are:
- Time. That time will be delayed additional to the falling time. It can also be negative.
- H.A. It stands for Height Above Sensor. This is the distance between the nozzle and the sensor.
- H.U. Height Under Sensor - the distance between the sensor and the surface of the water.
- Mirror L. Activate this if the cameras mirror lockup is active. I really recommend to use this!
After all parameters are set, the camera can take place. It should (has to) sit on a tripod. Additionally I use a flash. Some flashes are able to work with a 2.5mm jack.
The focus is set to manual. Because I can place the nozzle really exact I know where the drop will be later. There I place a small piece of wood, stone, etc which I can focus. The aperture is relatively high (about f/8 to f/16). The lens I use is the 100mm f/2.8 macro lens from Canon.
The dropfluid, as I call it, comes form the nozzle and creates the splash. It is filled in a plastics syringe. I use the following fluids:
- Clear water - creates big splashes
- Water-guar-micture – results in bound forms.
The guar gum-mixture is prepared with 5cl spirit. This spirit is mixed with one teaspoon guar gum. After stiring it pour it into a container with about 2 liters of warm water. Stir it again. Then let it rest for a couple hours. Finally filter it by using a napkin or something else.
The water in which the drop falls is only filtered. As a container you can use whatever you want, a vase, glass, a pan, etc. I fill it up until the rim, so the 'horizon' melts into the background. Behind the container you can place colored panels to get neat effects.
An external flash could take place behind those panels (if they are translucent). This gives superb coloring effects!
If you start it, the controller calculates all parameters and gives the signal, that you a droplet can be released. That signal is a bright lighting LED. Only if it is bright all steps are done to create a picture.
Have fun by doing it on your own! Finnally here's the first picture I've done with that rig.
Questions and comments: deloarts.wordpress.com