QA: How to Shoot Events Without TTL Flash
Technology is great. But it can also make us its slave.
For instance, TTL flash is pretty good at solving lighting problems on the run. (See, McNally? I'm open-minded...) But those problems existed long before we had TTL flash—or TTL exposure metering, for that matter.
And yet, we solved them on a regular basis. Even without feedback on the backs of our cameras. Or autofocus. While walking five miles to school barefoot in the snow. Uphill. Both ways.
Tell Us About The Olden Days, Grandpa...
That's essentially what he is asking. So I'm gonna. And with it, a hack that amounts to a poor man's TTL.
To back up, TTL stands for Through The Lens. And a TTL flash measures and regulates its output in real time by measuring that light right at the sensor. But in Christopher's case, the combo of a digital Nikon D700 and an aging Nikon SB-26 doesn't offer TTL mode. So he doesn't have that option.
Most older flashes don't have TTL, but they usually do have what passed for TTL at the time. It's called "automatic mode," and usually denoted as "A". In auto mode, the flash is told what ISO and aperture you are using. And you actually have to dial these in, as it is not automatically transferred from the camera as it is today.
Using that info, the flash will self-regulate its power using the light reflected off of the subject and back into a small sensor in the front of the flash. This exposure is obviously dependent upon aperture and ISO info, which is why you have to dial it in on the flash itself.
And mind you, all of this calculation is happening inside the flash unit. No camera-based calculations are happening. So you can sync with a dumb hot shoe or a PC cord or a PocketWizard or what have you.
The one thing you have to remember is to make sure you do not obstruct the sensor on the front of the flash. So no umbrellas, no softboxes, etc. (Our go-to light mod in this case was usually a large bounce card strapped to the back of the flash, which was aimed straight up.)
How to Control It
Obviously, this is a pretty low-tech solution. And there can be problems. For instance, if your auto sensor on the front of the flash is full of schmutz, you'll consistently overexpose your subject as the light tries to barrel through the clogged window to calculate the exposure. So keep that clean.
But amazingly, you can get a high degree of control using auto. Here's how.
First, let's say for the sake of argument that your flash has been set for you to shoot at ISO 400 at f/4. So it will pump out what it thinks is the appropriate amount of light for f/4, regulating realtime, based on the amount of light it is receiving bounced back from your subject.
If your subject is consistently hot, all you have to do is to dial down your lens' aperture a little—say, f/4.5 or f.5.0 or even f/5.6. Since the flash does not know you did this it will continue on its merry way pumping out the (now corrected) amount of light for what it thinks is for f/4.
If the flash is too dark, you'd similarly open up. Which is one good reason not to start this process shooting wide open.
What About the Background?
Better to think of it as your ambient component—i.e., the areas the flash is not reaching. And the best way to do that is to shoot in aperture-priority mode, which locks down your aperture and lets your shutter speed float based on the ambient light level.
And in shooting this way, the camera also gives you an easy way to control that component, too. You'll do that with your exposure compensation dial. I like to start at minus two stops for my shutter speed, or "EV-2". This will underexpose your ambient by two stops.
If your ambient is too dark, dial up your compensation. (For instance, EV-1 1/3, or even EV-1.) That will brighten up your backgrounds. If they are too bright, dial the compensation down. (For instance: EV-3.) This will similarly darken the areas.
As always when shooting flash and ambient, you'll want to try to shoot into the ambient light. In other words, choose a shooting direction to make the backgound the brightest ambient portion of your scene. This will both minimize ghosting and give you an often much-needed boost to your shutter speed in dark rooms or outside at dusk.
Is it low tech? Yeah, it is. But it works surprisingly well—especially if you are getting the real-time feedback that a digital camera offers on the back. Which again, we did not have.
So just because you don't have an expensive flagship TTL flash to put on your camera doesn't mean that you can't roll run-and-gun style when you have to.
Got a lighting question? You can always hit me via Twitter at @Strobist. I'll do the best I can, 140 characters at a time. And if it will help others you might end up with the long version, here.
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