Here’s a quick portrait I made of Becki as she goes down the ancient staircase at Madeley Court to her wedding a couple of weeks ago. As often with indoor shots and winter weddings, this one’s helped out by a little bit of flash. I thought I’d tell you about one of the technologies I use to get the shot fast. This is going to get technical. If that doesn’t float your boat, feel free to just admire Becki for a bit.
Flash obviously lightens up a dark scene, and for simple party photos in the dark that’s fine. But for professional results you want to control where the light comes from and how strong it is, so it looks natural. Getting the flash off the top of the camera is key, and you need a way to control it if it’s not plugged in anymore.
For most of my flash work I use a set of awesome flashes by Godox. They’re fully manual, radio controlled and have a whopping great Li-ion battery instead of AAs. I’ll tell you about them another post. But for walking around and TTL (which basically means automatic power level), I haven’t found anything to beat Nikon’s own flashes, so I currently use a couple of SB-700’s.
Bit of flash history
How does a flash control it’s power level? Well in the beginning they didn’t. The first flashes just gave you a big whomp of power every time. You had to use a combination of aperture, ISO and distance to get the right exposure. And of course you wouldn’t know if you’d got it right until the film was developed. Pain. Next came ‘Auto’ flash. These had a little light sensor on the front to measure how much light bounced back from the subject. When it’d had enough, it shut off the flash. The problem with this is it’s pretty unsophisticated. It’s just looking at the whole scene as one big pixel which it assumes should be medium. Most things in a wedding photographer’s life are not medium! White dresses next to black suits, etc.
Enter TTL or ‘Through The Lens’ flash metering, which does exactly what it says. The light sensor is now inside the camera, pointing at the frame of film. As the flash exposure happens, the sensor is seeing the actual image that’s being recorded. Now the lens and the composition won’t mess up the results. Later versions had multiple segments so rather than one big pixel, the computer can now take a guess at different zones and for example not keep pumping out flash to try and lighten the sky (impossible) but stop once the people in the foreground are lit. Nikon was always the best at this, until digital threw us a curveball.
The digital problem
The problem with digital was that light doesn’t reflect off a digital sensor the same way it did from a frame of film. So the in-camera flash meter watching the shot live as it happened didn’t work anymore. Then Nikon came up with the pre-flash meter. Now when you press the button the first thing that happens is the shutter opens, and the flash fires a tiny little bit of it’s power. It’s nowhere near enough to light the scene, but the sensor can still see the difference it makes to certain parts of the image. From that it can calculate the power needed to light them fully, and it sends that value to the flash to fire for the main exposure.
This all happens in a fraction of a second, much faster than most people can blink. But just occasionally I meet someone who can blink that fast, and if they blink at each pre-flash, the main exposure will have their eyes shut every time! So we have an extra button for that. It fires the pre-flash separately so when the main exposure happens the first flash that comes is the real one. You can’t blink that fast.
Get it off the camera
That’s all grand for a flash on the camera. Now it won’t matter where you point or bounce the flash because the sensor is seeing the actual results on the image. But how do we take the flash off the camera and still control it?
Nikon’s solution for like, a decade now has been iTTL, a system of optical pulses from the camera that tell it’s flashes what to do. The really cool part is that you can have multiple ‘banks’ of flashes doing different things. Each time you press the shutter, the camera sends the signal to the flash to test fire, records the effect on the image, calculates the power needed and sends back a coded pulse to tell the flash. It does this for each of the groups of lights which can be affecting different parts of the image before finally sending the signal to fire all groups at their respective levels. Each time you press the shutter!
Back to Becki
I’m usually only using one flash in iTTL. For more complicated setups I go for the Godox kit because I want manual radio control. But the shot above is a great example of when a quick off camera flash can make an image. As I climbed this staircase to the room where Becki and her girls were getting ready I knew I’d want a photo of her as she went down it. But it was dark, and the light was coming from unflattering places. So I’ve got the flash in my left hand, held out to the right, pointing down towards her. You hold the camera in your right hand, so you have to get your left arm underneath which is weird.
I’ve zoomed the head in a bit so rather than lighting the whole scene we’re just sending a narrow beam down to light up her face and body. This draws the attention to her. You see a colour difference between her and the background here. I did try using an amber gel to match it, but I didn’t like it as much. I like the top of the dress looking crisp and white here, but the warm colour of the room feeling like a cosy winter wedding. You can see the difference on the left of her face and arm.
But this technology is wonderful because in wedding photography, everything has to happen fast. It took me much longer to tell you about this shot than to take it. How long can you really delay a bride from her wedding – ten seconds? For an image like this? Totally worth it.