09/21/14

Low cost laser barrier Photography

_MG_9916-2

After trying to capture an exploding water balloon with a very rudimentary method (see here), I dedided to try again but using a low cost laser barrier and a LDR (Light-dependent Resistor) to get more accurate results.

Materials:

  • 1 Laser diode (5v, a pack of 10 is very cheap on eBay).
  • 5v Power supply (or 4xAA batteries) for powering the laser.
  • 1 small LDR (Light-dependant Resistor)
  • 100K variable resistor
  • N3 camera connector (Canon 5D) or minijack depending on camera model.
  • Bag of water balloons
  • Also a flash is necessary to freeze the motion, and also using it at the minimum power possible.

Circuit:
 
Knowing that to shoot the camera with an external cable we need to short-circuit two wires (Shutter and Ground), I put a 100K variable resistor between the two wires and saw that the camera shoot when I set the resistance lower than 25K.
Once we know that resistance, we know that if the sum of the variable resistor + LDR is < 25K, the camera will shoot.
To build the circuit I just put the LDR and the variable resistor in serial and then connected them to the shutter and ground cables of the camera. The variable resistor serves to callibrate the initial status and set the camera to a point that almost shoots. Then, when we point the laser to the LDR, its resistance lowers and the overall resistance between the Shutter and Ground cables will be < 25k, so the camera will shoot. In normal conditions, when the water balloon is in front of the LDR, the camera won’t shoot because the LDR resistance is too high to trigger the camera. When the water balloon explodes, the laser beam will illuminate the LDR.

Camera and flash settings:

  •  Shutter: 1/125 (if there’s ambient light it should be faster).
  •  Lens focus set to manual.
  •  ISO 400
  • Apperture: f/8-f/12 to get enough DOF.
  • Flash power set to 1/64 and zoom at 105, about 60cm from the water balloon (on the left). Also, the flash is triggered from a remote emitter in the camera.

Once all is prepared, we just have to tie a water ballon to the rope so that it is placed between the laser and the LDR, and when we make the balloon explode with a needle the camera will automatically shoot.

Original idea:

20140921_191817

Setup and circuit:

20140921_154954 20140921_155034 20140921_155136 20140921_155223 20140921_174249 20140921_180640

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Results:

_MG_9912_MG_9918

 

 

 

 

 

 

 

 

 

 

 

 

Notes:

  • I built the same circuit with a LDR of a greater size and it didn’t work so well, so I recommend using a LDR of the same size as the laser point if possible.
  • I noticed a significant delay between the balloon exploding and the camera shooting, which I didn’t find so slow in my old Canon 40D. To solve this I recommend setting the water balloon higher than the camera frame, so that the balloon doesn’t appear in the frame until the water balloon falls.
07/13/14

Creating a new PhoneGap 3.5 project on Windows

I upgraded to Phonegap 3.5.0 a few days ago and I found some differences when creating a new project for Android, so after a couple of errors I ended up using this steps to create a new project for Android under Windows 7:

  • Download and install Git: http://git-scm.com/download/win
  • Download and install Node.js: http://nodejs.org/
  • Open a new Ms-DOS window and type:

npm install -g phonegap

  • Now create a new project:

phonegap create NewApp com.example.NewApp NewApp

  • Enter to the new project directory and type:

phonegap build android

  • If we need to add plugins:

phonegap plugin add org.apache.cordova.media

phonegap plugin add org.apache.cordova.file

  • Build again

phonegap build android

  • In Eclipse, create a new project from existing code, and select the project previously created.
  • Two projects will appear on the list, MyApp and Myapp-CordovaLib. Select just MyApp, and enable copy to workspace.
  • Once imported, go to project properties->Resource->Resource filters and delete the two existing filters (This way we’ll see the www folder in assets).
  • Go to project Build Path, and in the source section, add folder and select CordovaLib/src folder of the current project.
  • Build from Eclipse to check everything worked.

06/12/14

Making of “Ephemeral dreams”

To create this work, I mixed a 3D rendered labyrinth with some photos. The final photo is composed by these three kinds of images, created in this order:

Hands: I used a Canon 17-40L lens at 17mm, f/20 to get a lot of dof and flash on the right with a small softbox.

hands_setuphands

 Sand falling:

I needed to get some photos of sand falling and merge them together to create the parts where the labyrinth was melting. My photoshop skills are very limited so I had to get a good perspective and shoot at 17mm too in order to facilitate the edition. I did some tries using a shutter speed of 1/30, also f/20 and natural light to get a kind of “silk effect”, but when I joined the captures with the 3D labyrinth, the result looked like plastic. I repeated the sand captures using flash to get the opposite appearance (freeze the motion), and I stuck with that setup for the rest of the photos I needed (just 3 or 4).

sand_setup

sand

 

 

 

 

 

 

 

 

 

Labyrinth: Modeled with 3D Max 2014 with iray. First I created in Photoshop a 2D image in black and white with the labyrinth I wanted, until I got this:

plantilla_laberint2

I added some layers and used the gradient tool to darken the corners so that the labyrinth appeared that was melting when applying later the “displace” modifier in 3D Max (depending on the shade of gray, the height of each wall will differ).

Then in 3D Max, applying the modifier “displace” I used the displace map created to get the 3D appearance. With the modifiers melt, noise, wave and bend I added some imperfections, and also edited the mesh of the labyrinth to melt much drastically the middle part and the sides. Result:

laberint_high_low_mid_fused

Each part was processed with Lightroom to add some dramatism by using clarity and blacks, and changing the temperature of the captures, and also desaturating to have a similar appearance in all of them and facilitate the Photoshop part.

Final photo:

04/8/14

Making of “Captivity”

In this one, I wanted to create an mood similar to a jail by projecting the light through something like “metal bars”.
I used a cutter and cardboard to create my bars and set a flash behind it on the right of the camera to project the shadows of the bars onto the composition.

I could have created shadows with a more defined borders by placing the flash farther from the cardboard, so that the relative size of the flash would be smaller, but for me it was ok this way, because it can be interpreted as an office curtain too, which I also found appropiate.

To emphasize the highlights and textures of my hand and give the impression that the person was in tension and sweating, I used a dropper with water to wet my hand. I used an old keyboard I had at home because by combining it with the b/w processing seemed more adequate to me than a modern keyboard.

Before:

20121011_200023

After:

04/3/14

Making of “Drowning”

To create this photo, I used my computer screen again as a softbox. I wanted to get the silhouette of the glass so I didn’t need a flash, and using a tripod I could choose the dof I wanted and then the necessary exposure time to get a white background.
I placed the razor blade very carefully before filling the glass until it held in the position I wanted, and then I started to fill the glass with water using a dropper, and also doing some photos of the composition while I was filling it, just in case the razor blade changed its position, in which case I could loose the shot.

Also, in the first attempts I noticed that the edges of the glass weren’t as defined as I wanted due to unwanted light coming from the screen, so I placed a couple of books as flags to reduce the amount of light on the sides of the glass to get a more defined silhouette.

Finally, I used photoshop to create the silhouette of a face and then its symmetry with a copy of the layer.

Before:

 20140216_190456

After: