Story Behind the Photo for April 2020: Purple

Doug Budzynski 

Camera: SonyA7rii
Lens: Tokina 100mm f2.8 macro Camera Settings: 400 iso,

2.5s,
f/16,
White balance set to flash, Manual focus,
Trigger set to 2.5s delay Live view off.

Other equipment: *Raspberry Pi mini computer + additional wiring board 2 speed lights (flashes),

Electric solenoid valve for water drops
Desktop computer with Sony remote software (optional to quickly review results).

*(Raspberry Pi is a series of small single-board computers developed in the United Kingdom by the Raspberry Pi Foundation to promote teaching of basic computer science in schools and in developing countries.)

This project was actually something I had started last summer, but with moving to a new home, I had boxed everything up. With the stuck at home period, I had the opportunity to bring it back out.

It all started with a Raspberry Pi mini-computer kit my daughter had gotten. The kit was originally to build a voice box like the Amazon Echo, and so Taylor and I built the box. Success. We then decided Alexa is easier to use.
During the building of the kit, I learned that these mini computers can have a lot of versatility in doing many projects. While browsing on the web, I stumbled on a website that actually used a Raspberry Pi for speed photography. I had always wanted to do the water drop capture, but found trying to do it without something to control the timing of everything, it is pretty hard to be successful. I have seen devices advertised for specifically doing this but I always find it more fun to build your own if possible.

I had to add some additional wiring, set up a water source with an electric solenoid valve to actuate the drops, add the pool of water, and of course, figure out how to have the computer tell everything what to do. The pictures below shows the setup I did to do all the controlling.

For the execution of the drops, I did a lot of internet research and I learned there a lot of things to consider. The size of the valve opening, the distance of the fall, the size of the bowl, and the type of the liquid used all make a difference in the what your results would look like. I tried straight water (this is what you see here) and found as everyone else did, water is hard to work with. In the end, I was using milk in the bowl to give the creamy surface, but the water bottle that holds the liquid for the drops, was cold water with glycerin added to make it a little more viscous. I used a 2 drop method where a second drop was released less than a 1⁄2 second after the first drop. I also found that for my setup, 20 inches was a good falling distance between the valve and the bowl surface.

For lighting, I used 2 speed lights. Both were set to 1/32 power to minimize the duration of the flash. One mainly for lighting the drop surface and the second flash was to help with shadows and lighting the back board, which was a purple paper. Both flashes were triggered by the Raspberry Pi about a 1/2 second after the second drop was released.

I set the camera shutter to 2-1/2 seconds because that is about the amount of time I needed from the time the shutter release was pushed to the time the action happened. This was all done in a dark room, so the camera only saw what was happening at the time of the flash. Once I had the timing of everything in place, I could do several photos a minute with a successful capture of the action almost every time. I did have my camera connected to the desktop computer where I used the Sony remote software to control the camera shutter and I was able to see the results of the shot on the computer screen.

My sequence went like this.
1. Trigger the camera shutter, manually.
2. Release the first drop of water (Raspberry Pi).
3. Release the second drop of water 0.1 second later (Raspberry Pi). 4. Trigger the flashes (Raspberry Pi).
5. Close camera shutter.

I found getting the liquid purple was not as easy as I had thought. I thought I could just mix red and blue dye and to get purple, but this was not working for me. Everything I had tried, following suggestions on the internet, made my water or milk turn closer to a brown. My guess is that the food dye I had at home (store brand) was not pure in color. Fortunately, the easter egg coloring kit we had at home had a purple color.

For final editing, the only thing I did was cropping and some additional color adjustment using Lightroom to get closer to the shade of purple I wanted.

I found that with this setup with the Raspberry Pi computer, I could do several different ideas for stop action photos. So I used the same idea of controlling the flashes for the stop action photo to create my second photo of the alligator eating the purple peeps. The only real difference was instead of controlling a valve to drop liquid in the air, I controlled a solenoid that would open the bottom of a box that held my peeps. Here is the Youtube video where I got this idea, https:// www.youtube.com/watch?v=sl2hs_0tLe4&list=WL&index=20.

My sequence for this photo went,
1. Trigger camera shutter. Manually.
2. Open box for peeps to drop (mini-computer). 3. Trigger flash (mini-computer).
4. Close camera shutter.