"Light Sculpture" It took me three years to produce this one photograph, a record of its creation.


I would like to share the production process of "Light Sculpture" project.
I hope you will find it exhilarating and stimulating to photograph water.

Light Sculpture

Have You Ever Really Seen a Rainbow? 
As I zoomed in, I realized what was there. The sunlight in the water droplets warps, reflects, and disperses, showing us the rainbow.

Light Sculpture #22, 2019  Edition 3 + AP2
125” x177” [318cm x 450cm]
Data size 37,686px x 26,697px, 1 giga pix

Enlarged part of the image.
You can see each individual water drop.

We feel lucky and happy when we see a rainbow.
But what are we seeing?

Within each drop of water, there is a color, and the aggregate of these colors form a rainbow.
I believe there is a beauty that cannot be seen with the naked eye.
This work is an attempt to express that.

Viewed from afar, it is a rainbow.
When you get closer, you will discover the beauty hidden in it.


I love shooting water-themed shoots and thought I was good at it.

When I came up with this idea, I expected it to be completed in three months, but it took three years.


■ Water Sculpture / Discovering color in pictures of water.

Water Sculpture #9, 2009

This was the inspiration for Light Sculpture, a piece I created over a decade ago called "Water Sculpture".

Lighting was done to create sharp, unblurred shadows so that the water would look like a sculpture.

Nikon D3X, broncolor sunlite

When photographing water with a point light source such as sunlight, colors may appear in the water drop. At the time, I did not pay attention to where the colors came from, but later I realized that this is the principle behind the appearance of rainbows.

I decided to use it to create a work of art.

■ Principle of rainbow visibility

The truth you seem to know but don't.

https://education.nationalgeographic.org/resource/rainbow#undefined

This diagram illustrates the principle of a rainbow.
Light entering a drop of water is refracted and reflected on the backside and refracted again as it exits the front side. The light is spectrally split to reveal the color.

After one reflection, it becomes the primary rainbow.

https://en.wikipedia.org/wiki/Rainbow

It becomes a secondary rainbow when it is reflected twice.
This is weak light, and the color order is reversed. If you look closely at an ordinary rainbow, you will notice that there is another rainbow on the outside.

Production Process

Test in sunlight

I checked in the sunlight to see if the color appeared per the principle.

First test shoot using sunlight on the roof of the NY studio
【Day 1 April 14, 2016】Nikon D810 28mm 28-300mm ISO400 f 3.5

Rainbow visibility test with large water droplets and mist

Water drop test to check color appearance in sunlight

Glass ball test to see how colors look in sunlight

Then I started shooting in the studio.

Nikon D810 28mm 28-300mm ISO400 f 3.5

However, I soon realized that there were many problems that needed to be solved.


The three main problems with studio photography were:

1. [Water droplet problem] Some size and perfect spherical shape

2.[Strobe problem] Short flash duration and power 

3.[Image quality problem] Large prints & details are also important

[Water droplet problem] A certain size and a perfect sphere

Water droplets must be of a certain size to be captured in a photograph and must be perfectly spherical to form a rainbow.

If it is fog, it forms a rainbow
Nikon D810 28mm 28-300mm ISO3200

Large water droplets distort the shape, randomize the color, and fail to form a rainbow.
Nikon D810 28mm 28-300mm ISO6400

Shape test of falling water drop / Phanton Flex 4K
Shape test of faImmediately after falling, the speed is slow, but the shape is greatly distorted.
The larger the water droplet, the larger the distortion.

Test for alcohol and glycerin
I tested liquids other than water to find the right size and viscosity.


I wanted to use pure water, but to obtain perfect spheres, I mixed about 30% glycerin.

Final rig used
The tip is a pipette tip for research use.

As the pump keeps the liquid flowing, only the water evaporates, changing the ratio and the refraction angle. The position at which the rainbow is generated shifts. Therefore, the ratio of water to glycerin had to be constantly adjusted.

Result

Using water containing 30% glycerin and the appropriately sized pipette tip,  I was able to obtain nearly spherical water droplets with a diameter of 3 mm.

[Problems with strobes] Short flash duration and power

Water droplets of 3 mm in diameter are falling at high speed, so an ordinary strobe will blur the image. If the light source is large, it will not be spectral. I needed a light source that was powerful, as small as possible, and with a short flash duration.

Highlight is blurred vertically due to the high speed fall

Strobe Type

Strobe Testing

I tested all potential strobes available on the market that seemed optimal

Industrial strobes and two tubes in one head.

Light Source Size

Comparison of light source sizes as seen from the subject

Flash duration

Testing the flash duration

A disk with lines drawn upon it is rotated at high speed and photographed. Even broncolor and Profoto, which are known for their short flash duration, proved unsuitable for this project.

Spot Light

Reflector and spotlight testing
Spotlights are advantageous for producing the amount of light needed.

Color in strobe light

Color Test

I could not find the best strobe on the market.

Strobe used

Nikon clip-on strobes

I ended up using a bundle of six Nikon clip-on strobes for the main light.


Controlling flash duration and output with an Arduino

I modified the program so that it would change flash duration. I bought many types of strobes on eBay and looked for a model that I could hack the program with. I found the perfect strobe, however it was discontinued, so I had to order it from different countries throughout the world on eBay. I connected a custom made socket to the electronic contacts and controlled the flash duration and output with an Arduino.

For the background, I used Vela LED lights made in England.
The flash duration is very short, 1 / 2,000,000s

Vela LED light 
Flash duration 1 / 2,000,000s

www.vela.io

Result

Main light instead of sunlight

Six Nikon clip-on strobes with improved programming.

Flash duration about 1/50,000s

Background lights

Four Vela (LED lights) are used.

Flash duration is 1/200,000s

[Image Quality Matters] Large prints & details are also important.

The resolution needs to be good enough to make the water drop look good when viewed close to the print. I tested which camera and lens to use.
First, I made actual prints to determine the final print size and the size of the water drop on the print.


Print size: 3m x 4.5m
Size of polka dots on print: 1.5 cm

Determining the angle of view

With ordinary subjects, the distance to the subject is determined by considering perspective, but since a rainbow is the same no matter what distance one shoots it from, the angle of view (focal length of the lens) was determined by which part of the rainbow is to be cropped.

In order to express the rainbow in three dimensions, I adjusted the amount of water drop present in the space so that the rainbow arcs from the front to the back.

Most rainbows in nature should appear flat.

Test angle of view to capture the rainbow

Focal length of lenses in each format

Selection of photographic equipment

Film Camera Test

Film Test

I liked the tone of the film, but the resolution is not sufficient. Considering the work efficiency, I gave up using a film camera.

Digital camera test

Sonyα7RⅡ, Sonyα7RⅢ, NikonD850, NikonD850,PhaseOne IQ3, Fuji

Even with Phaseone 100M, the image quality was not high enough, so I decided to split the image.

Sensitivity and Lens Test

The strobe did not provide enough light, so it was necessary to shoot at a high sensitivity.

Depth of Field Test

Bokeh test at different apertures

Rolling shutter test

Water droplet distorted by rolling shutter

I considered using steady light and a fast shutter speed.
However, the rolling shutter distortion was too large for the electronic shutter of the time.

Split shot Test

Split shot using a view camera
Using a lens with a wide image circle
Composite with panoramic rig and software
Telephoto lens used

Final equipment used

Sony α7RⅢ + Mamiya 210m lens + custom panorama rig

120 segments, shot and composited with PTGui software

ptgui.com

Due to insufficient light, the image was shot at ISO 1600, so noise was noticeable and Neat Image was used to remove the noise.

ni.neatvideo.com

Different distances from the lens are also split and combined later.

Result

Equipment used

Sony α7RⅢ + Mamiya 210m lens + Custom Panorama-Rig

Composite using Neat ImagePTGui

Print

Shooting with printout for confirmation

Photography Data Sheet

One page is one section.

The light intensity of the strobe is also changed.

Composite in Photoshop

This is Photoshop data. I usually use a Mac, but decided to purchase a Windows PC for this file.

It took about 30 minutes just to open the file.

I retouched it little by little for over a year.

37,686px x 26,697px 1,006,103,142px File size : 388.4G

■Exhibition

Although this is such a thoughtful work, it has not been exhibited at a/the gallery because it is too large. It was exhibited only in my studio and in the Metaverse space. I am currently looking for an opportunity to exhibit it.