We saw last week how to take high-key photos with the means at hand. We'll do the same for some low-key portraits. And the process is a little more complex than it seems, since the low-key is not simply the opposite of the high key. The method requires precise use of its flash. Because it is him, his power, his dosage and his angle which will give or not scale to your photo.
As for the high-key, we place ourselves in an environment that is anything but professional. No studio, no black background, and just a cobra flash. The minimal equipment, which should allow us to photograph in low-key in a normally lit room, and without studio tricks. Not easy at first? Indeed...
The first thing to do is to make sure the background will be black. For a high key photo our histogram showed almost all of the information in the bright areas. Logically, in low key, it will be the opposite:
For this, we will adjust its camera so that it exposes well... that is to say that it takes very dark photos. In our case, by switching to manual and setting the sensitivity to minimum (between ISO 100 and ISO 50), with a shutter at 1/320s, the result is impeccable:
Attention to a detail... do not lower the shutter speed too much. Indeed, we are going to work with flash, and care must be taken not to expose beyond the maximum synchronization speed of the flash. In this case, the SB-600 used here can synchronize at a maximum of 1/320s. The easiest way to properly adjust your exposure is to set your trigger to this maximum speed, lower the ISO sensitivity to the maximum, then do a few tests by modulating the aperture. First fully open, then gradually closing until the image is very dark.
The flash will be our light source. The only. Used remotely, it is sometimes to be handled manually. Which isn't a real problem, given that we're going to be groping a lot for the rest. Take the time to familiarize yourself with the use of your flash, and with its settings in the menu of your camera. It's primordial.
In the studio, photographers gladly use umbrellas, beauty bowls, softboxes... if you have them or if you have access to this type of equipment, don't deprive yourself!
Placing the subject... and the light
This is where things get tricky. It will have to be done empirically. Go little by little, take a lot of photos of adjustments until you get the desired result. The difficulty here is threefold: we are working on a deliberately black stage. The only light will be that provided by the flash at the time of release. Must therefore:
that the flash is not too powerful so as not to illuminate the background
that the flash is well enough dosed to illuminate only what you want
that the angle given to the flash is judicious.
And very quickly you realize that the number one trap is "spilling", this phenomenon which causes your background to be lit by the light of the flash, and not only your subject. And the first results are often discouraging:
Flash too strong, badly positioned, badly dosed... the photo is muddy, the background lit, and the subject badly exposed. Argh!
But despite appearances, it's a good start, and a situation that's easy to correct. Several options are available:
use a diffuser
decrease flash power
move it closer or further from the subject depending on the desired effect.
We approached the flash, set it to half power, and adorned it with a diffuser. The result is already more convincing. But still quite far from what we expected...
To avoid any problems, we can also move the subject to remove it from the background. But this is not always possible.
By continuing to play on the distance between the flash and the subject, and on the power of the flash, we quickly arrive at an even more marked, more interesting result:
From there you can start to really work on your subject. By moving the flash we will modify what is "seen"... and therefore all the content of the image.
Attention, we specify once again that these photos were taken in a normally lit room... and not at night or in a dark room.
Development and post-processing
The development is quite simple. If the shot was good, then few things will need to be retouched. We can amplify the contrasts, lower the luminosity of the dark shades to accentuate the blacks, and increase the intensity of the light shades... if necessary.
Be careful if you are shooting in RAW... the result of importing the file into a dematrix will certainly be very different from that returned by the LCD screen of your box when shooting. Often your image will be much brighter, and the blacks less dark. We will have to rework this a bit, but we quickly get back on our feet.
In addition, do not hesitate to use all the weapons made available by your demoser. No one is infallible and a beautiful low key image can be "spoiled" by a poorly controlled flash and a background that is too bright. If the subject is good, do not hesitate to play with the localized corrections offered by Lightroom or ACD See for example, to darken or lighten what needs to be darkened.
Finally, the low key and its marked contrasts go very well with a passage in black and white. Feel free to try the same shots in color and monochrome. Even if it means pushing the contrasts in black and white a little further. Often the result is quite interesting.