How To: Easily Fine Tune Your Flash Right From the Camera

Strobist reader (and relative lighting newb) Ron Ibarra of New York City asks, via Twitter:

"I can't control the flash through the PC cord. Am I doing something wrong?"

Nope, Ron, you are not. A PC cord is what we call a "dumb sync," meaning it only triggers the flash but does not otherwise control it. And if you are a smart photographer, all you really need is a dumb sync.

That's because you can control everything right from the camera itself. And today's follow-the-bouncing-ball post will show you the super-easy way to do just that.
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Shown at top is The Spear Center in downtown Columbia, MD. For many years it has served as the main gathering space for local social events. I photographed it for a piece on Columbia's iconic buildings in transition.

In shooting it, I wanted to call some attention to the beautiful, "vertical" wood ceiling which is its main design element. So I lit it with a couple of speedlights.

And the process for this shot serves as a good example of easily controlling both your flashes and the ambient from your camera with a dumb sync. (In this case I was using an IR remote, which is a manual-only—i.e., "dumb"—sync.)

Normally, controlling flash from camera is a two-step exposure shifting process. But by using the camera on Aperture priority, you can shift flash or ambient quickly. And you can do either one by changing only one setting.




Okay, so here's the room as seen in ambient light only. It's 90% memory-filled aging function room and 10% creepily empty, which is what drew me to this perspective. But I definitely want to call attention to that ceiling, which is getting no love from the ambient.

I can turn on the lights, but that's too much—and too warm given they are tungstens. So let's put a couple of flashes on the floor. We'll hide them with the door frames in a minute:




Doesn't get much more simple than speedlights on the ground. Their location is obvious now, but I'm willing to bet you didn't really notice it in the final pic up top.




So here's a first try, right out of the box. Not bad, actually. What's the exposure? Doesn't matter, as you should think in terms of relative changes and not absolute settings. It's the process that is important, not the f/stop.

We're on aperture priority (you'll see why in a minute) with a reasonable, middling aperture. I am starting at a mid-range aperture and at mid-range power on the flashes. You'd be surprised at how often that'll get you close right from the start.

But what if I want the ambient a little darker, without changing the effects of the flash? I need to move the shutter, but leave the aperture where it is. To do that in aperture priority, I'll just dial my exposure compensation button down one stop. Aperture stays the same, but the exposure will shift through the camera choosing a faster shutter speed:




There we go. Ambient has been dropped a stop but the flash remains untouched. That's why aperture priority and manual flash go so well together. And as long as my shutter does not go over 1/250th, I am fine.

It's looking kinda moody. Let's drop it another stop and see what happens:




Ambient gets a stop darker and the flash remains the same. Easy, right?

This is a little too dark for me. Totally subjective, though, and there is no right or wrong answer. But let's keep it dark and crank that flash up by remote control.

You know where this is going, right? We'll open the aperture and leave the exposure compensation where it is. Result should be a brighter flash and a constant ambient. What the hell, let's open it a few stops and go to wide open at f/1.8:




And the flashes go predictably nuclear. Too bright for me, but this is just as an example. But there are other changes you should be aware of, too. Depth of field is nill because we are wide open. And while the ambient is the same in most of the frame, the corners are much darker. This is because the Nikon 28/1.8 vignettes the bejesus out of the corners at wide open.

Not that there's anything wrong with that. I love vignetted, creamy background wide-angle portraits. But it is good to be aware of properties in your lenses and adjust accordingly. So I probably won't be shooting any wide-open architectural shots with this lens.

Let's close the aperture down some, and tame that flash a little:




The flash drops down a bit and the vignetting cleans up. (The latter fixes pretty fast as you get away from wide-open.) Also, we are getting some of our depth of field back. These are gross adjustments I am making here. But you can obviously choose to tweak this a third of a stop at a time if you like.

And don't fret about these multiple consequences of shifting your various exposure controls. As you get more comfy with it, you'll choose the changes that kill two birds with one stone in a positive way. It's really pretty intuitive once you have done it a couple of times.




Here's the final again, with the lines and walls cleaned up. (The 28 also had some barrel distortion, obviously.) Just a quiet photo, but an ideal way to show the quick-and-easy process of fine-tuning the flash, ambient or both right from the camera.
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Bonus points: For those of you who like to shoot sunset (or, shudder, sunrise) portraits lit with flash, you can see how this would make things super easy even with the quickly changing ambient of dusk.

Shooting in aperture priority, the aperture controls your strobe intensity. Exposure compensation button controls the intensity of the sunset. And aperture priority keeps you consistent as the light changes, allowing you to concentrate on more important things.