Lighting in the Dark: Summer Reading
It's still technically summertime in Maryland. But the temps are down, the humidity has eased and -- best of all -- the mosquitos are history. This is prime evening porch time for Emily, my nocturnal bookworm.
I walked out to visit, and to my eye the scene looked great. Unfortunately, it would look like crap in the camera. The tonal range would be far too much for the chip to handle.
But lighting is about controlling that contrast range. And when there is just a tiny bit of ambient, you need an even tinier bit of flash to fix it.
Here's a straight shot with no flash. It looks nowhere near the way my eye saw it, because my eye can see shadow detail that the camera can't. And I wanted that shadow detail, but I also wanted to preserve the ambient light that drew me into the scene to begin with.
Normally when we balance flash, we drop the ambient until the scene looks good, then sculpt the subject with light. But this is different. The subject is already in the neat light -- it's the deep shadow area we need to fix.
Get Your Ambient Exposure First
So first, you would set your ambient exposure for those neat highlights. (If you can call a flashlight off of a book a highlight.) The light was cool, but it was dim. The reflected flashlight on Em's face was ~1/30th at f/1.8 at ISO 1600.
Fine, I can handle that.
Next, I'll need to add some bounce fill flash at about 2-3 stops down to bring up the deep shadows in scene. I know it won't take much strobe, either. So I placed an SB-800 on the camera and bounced it off of the ceiling at 1/128th power.
The result was a nice, full flash exposure. Which is exactly what I do not want.
What I want is for the flash to support the neat ambient light without taking over the scene. So we need to get rid of at least 2 stops of flash. But I am already at my low limit of 1/128 power, so I cannot just dial it down.
There are several other ways to do this -- ND gel, cover part of the flash with my hand, etc. But I have no gels on the porch, and I need both hands to steady the camera at the slow shutter speed.
Of course, you also can lessen the flash's effect by closing down the aperture. By going from f/1.8 to f/4, I kill 2 1/3 stops of flash. But I also kill that much ambient, too.
So I open up my shutter speed to compensate, which means I am now shooting at 1/5th of a second at f/4. Not ideal, but that's where I am at. The aperture (f/4) was the magic number where both my ambient and my flash could be balanced the way I wanted at the same time. And the correct shutter speed for the ambient at f/4 was 1/5th of a second.
If it sounds complicated, it really is not. It is the same process that we normally use to balance flash and ambient, only the roles of the two have been switched. And this allows you to make a quick snapshot that preserves the quality of the ambient light while compressing the contrast range.
Soup to nuts, this balancing process took way under a minute, which all comes down to practice. And that leaves more time for the important stuff, like hanging out on the porch on a summer night.
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