On-Axis Fill: Ring Fill Against Restricted Light

Having begun to explore fill with a ring flash, I knew there would be other ways to push light from on or near the lens axis. But before I tried them out, I wanted to learn how a ring light fill would work in combination with a more restricted key light.

Hard key light leaves hard shadows. And if you are not taking into account the ambient light (maybe the ambient light quality sucks, for instance) on-axis fill can reach into shadows and open them up in a highly controllable way.

Keep reading for two quick set-ups, and a refresher on ratio control without a flashmeter.


Swamp Thing

This summer as I was looking for any excuse to experiment with ring-as-fill, my son Ben returned from a day at camp wearing the shoes you see pictured at the top of this post.


My wife: "Do NOT come inside with those shoes. Clean them off with the hose outside."

Me: "Don't clean 'em yet! I want to shoot them. (... on your mother's great-grandma's antique cutting board, I did not say out loud...)"


Hey, we don't use the board for cooking. It is mostly used as decor against the counter backsplash. And it covers up the mess and tangled wires around the phone pretty well, too.

We only have a few minutes before dinner, so this will have to be quick. No problem, as I already have my background (secretly) picked out. I love shooting details like this for the family album, and these shoes say a lot about a well-spent summer day for a seven year-old boy.

Having seen what the ring would do against an umbrella, I wanted to play with some hard light. My thinking was, this combo will let me dial in however much texture I wanted by filling against a hard shaft of light.

But before I could make the hard key, I needed my ring flash as fill. I cranked my lens down to a very small aperture to hold focus and dropped the shutter speed to 1/250th to kill the ambient. Then, I adjusted the power output on the (manual) ring flash until I got the proper exposure.

(I was using a Ray Flash adapter fitted onto a Nikon SB-800 speedlight for the ring light.)

Now, since I was already way down on the aperture, I dropped the ISO a couple of stops to take the ring flash from being properly exposed down to a nice fill. I looked at the histogram and rear display and it looked like a nice "baseline exposure" for what would become my shadows in a moment.

This is no different than dialing down your ambient before you add in your key light, except that it was all being done with flash.

Now, for the hard fill.

Using a set of ten-dollar barn doors designed for small flashes, I closed off the spill of the key light until just a small beam was getting through from hard camera left. I used a 1/2-strength CTO gel to warm up the key somewhat to accentuate the color of the mud.

Given that my shooting aperture is set, as is the number of stops I have already dialed down my fill, the only thing left to do is to adjust the key light until the direction and exposure looks best.

No meters -- just eyeballing the relationship between the tones on the rear screen and making sure my histogram is not out of whack.

Quick and easy, and I notch another quick experience in my goal to get more comfy with on-axis fill. Honestly, the hardest thing about the shoot was smuggling the cutting board out of the kitchen (and back in) without Susan noticing.

I really like the ring-against-raking-light look on the muddy shoes. The highlights are crisp, but you can see right into the shadows -- exactly as much as I want, thanks to the lighting ratio on the fill. The ring also gives that characteristic wraparound shadow -- which looks kinda cool against the highlights, too.


Ring Against Grid

A few days before Ben's shoes, I had done a little more experimenting with ring fill and hard light, and I found myself growing more and more comfortable both with the technique itself and the key-to-fill ratios.

This portrait of Em, done in the last days of single digits before her tenth birthday, was the first time I had worked with ring and grid light. But I already had a good idea what to expect, thanks to experimenting earlier with on-axis fill and umbrella key in Dubai.

There are two ratios to consider here, and if you are into reverse engineering should be able to spot them by looking closely at the photo.

The first is the ratio of the ring (which will end up being the fill) over the ambient. You can see how far the ambient drops off by looking at the depth of the ring flash shadow (around Em) compared to the surrounding bricks in the areas of the photo not lit by the gridded key light.

The second ratio is that of the gridded key light over the ring fill light. This you can see in the shadows on Em's neck and under her nose. (These shadows are left by the key light, but are lit by the ring fill.)

Which means that in this setting, we have two control levers to adjust the contrast range of the photo. The ring flash was about a stop and a half over the ambient and the gridded key (coming from upper camera right) was another stop and a half over the ring light.

(If this shorthand exposure information doesn't make sense, take a look at this post.)

I have to say, I immediately loved the look of the ring fill against the gridded key. It was crisp and open all at the same time, and every portion of the photo was tonally legible in a controllable way.


Baseline Exposure Cheat Sheet

I was starting to get familiar with the Ray Flash, and was finding that it knocked off a little more than the one stop (vs. direct flash) advertised by the manufacturer. To be fair, after testing I found it to knock off about 1.2 stops -- if you used the 24mm throw as a bare-flash comparison.

Real-world (50mm throw) I would call it close to two stops. But that is still plenty powerful to use as a beautiful fill light at portrait distances outside.

Having experimented in a darkened room, I tested it to see how much light it would throw in a given ISO and power setting. To help me learn get faster at future setups, I stuck my standard cheat sheet on the Ray Flash:


The numbers:

1/2 power -- ISO 400 -- 10 Feet -- f/8


From there, I could quickly interpolate differences in any future setups to get a starting point for my power setting in manual.

Comfortable with the tests, I was ready to try ring light as fill on an assignment -- confident that I probably would not screw it up completely.