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Shooting with light and filters?

Is this possible and why would you want to?

My Nauticam NA-7Dii with Inon Z330 strobes and BLUE filters!

In 2009, underwater photographer and (at the time) Nautciam USA Sales Manager Chris Parsons planted an idea in my head. It was the concept of using filters with artificial lighting when shooting photos underwater. Up until then I had always thought that tinted filters on your camera in conjunction with strobes were a big no-no. My own personal experience had shown, that with a filter applied to your camera, any artificial light would appear very red, and ruin your image.

Chris patiently explained to me that instead of a singular filter on your lens, a set of them - a red filter for the camera lens, and a blue filter for your strobe lights, would compliment each other, and the results could be spectacular.

For years this thought had been in my head, although I had never managed to experiment with it. Around the same time, Keldan had introduced this idea as the Ambient Filter Concept. But as a dive instructor, Keldan lights were outside of my budget. It also seemed like no one else had anything similar, and there were certainly no blue filters that I was aware of for underwater strobes - it seemed to be limited to just video lights.

Ten years later, it's now 2019, when I finally upgraded my strobes to the new Inon Z330. I was excited to see they offered tinted diffusers, however disappointed to learn, they were red-shifted filters (4900K and 4600K at the time of this writing) instead of blue-shifted.

At my heart, I am a builder. An underwater photographer who just happens to own a 3d printer, so I set out to make my own filter set. I first began by modeling the existing Inon Z330 diffusers in Solidworks.

a 3d model of an Inon Z330 diffuser, made in Solidworks.
a 3d model of an Inon Z330 diffuser, made in Solidworks.

I then sourced some blue translucent filament for my Prusa i3 MK3 printer. For the 3d printing geeks out there, I selected PETG (polyethylene terephthalate) as the filament for both its ease of printing, and its durability. Several hours later, voila! A set of 2 blue diffusers for my Inon Z330’s came hot off the printer.

My Prusa I3 mk3 3d printer, making some blue diffusers for my Inon Z330 strobes.
My Prusa I3 mk3 3d printer, making some blue diffusers for my Inon Z330 strobes. The structure you see in the middle is support for the top of the dome, which is removed post-printing.

The second thing I needed to do was to affix a filter to my Tokina 10-17 lens. Most photogs would just simply tape a piece of filter gel to the back of their lens, but I elected to 3d print a holder. I sacrificed an old Go-Pro filter, and ground the edges down to a circle, 20mm in diameter. I then printed a holder that fits perfectly inside of the Tokina lens out of a rubber-like material known as thermoplastic polyurethane, or TPU.

Now the blue filament I selected is quite dark, but this was a proof of concept test. I assembled my camera rig, grabbed a co-worker and jumped off the dock for a test dive.

Now you might be asking yourself, this all sounds fun, but why are you doing this?

Anyone who has ever dived Lighthouse Point reef, knows there is a massive sandy area between the mini wall, and the main wall, which is about 70 feet deep. The white sand, along with the blue Cayman water can make for some great shots when you are using a filter, or a proper white balance. I’ve always found these images quite pleasing. But subjects in ambient-light photographs can often have dark shadows. What happens when you need to add a bit of fill light to your subject? With a white balance or filter, the strobe light has a very red tint to it. This is where the blue strobe filters come into play.

These filters shift the color back to something more appropriate to the white balance of the camera. In my first test dive, I was very impressed with the results I had obtained. Here are some examples:

In the first image, we have the sand at 70 feet or so. Using a filter on the lens, with a custom white balance, we get a lovely blue water color, while the sand appears nice and bright white. The strobes are not firing in this shot. In the second image, the strobes are firing. The left strobe has a blue filter on it, while the right strobe does not. Note how red the light from the right strobe appears.

In the first image, we have the blue filters on. This allows the sand to be nice and white, with a blue water background, while the strobes provide some fill light to the feather duster. In the second image we have the filters off, which results in very red-tinted light.

Here is a shot of our Guardian of the Reef statue. In the first image, strobe filters were used. On the second shot, no filters.

Sonya in the 1st image - strobe filters. Sonya in the second - no strobe filters. This also illustrates how much light the filters absorb. The power settings on the strobes were the same in both images, the only difference was the strobe filters.

This allows me to get some shots like this:

Here, the ray is provided a bit of fill light, which falls off naturally to the surrounding sand and little to no color shift.

Same with these flying gurnards, the light the strobe provides has a smooth natural transition to the ambient light in the sand.

For the record these are not my best images. My camera settings were way off, mainly because I was too excited by what I was seeing on the LCD to pay attention to things like my shutter speed, and focus, and other important things.

But these are also unedited for color. And they illustrate a concept. Filters do work in sets with artificial light.

Now then, this isn’t a perfect solution. The tinted filters are too blue in my opinion. They also absorb way too much light, probably almost 2 f-stops by my quick calculation. A matched set of filters (lens and strobe) would be ideal.

However this was the first filament I’ve tried, but for a proof of concept, I think it went very well. Overall I’m pleased with how it went. I just need to refine it a bit. I’m going to try to get some lighter tinted filament. I’m also trying to revise my design to allow more light through.

Stay tuned for results from my future revisions!

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