Today in our technical lesson we experimented with lighting, and the effects it has on the mood of photos, we also learnt about high key and low key lighting techniques.
High-key Lighting
High-key lighting simply refers to images that are mostly bright, with a range of light tones and whites and not very many blacks or mid-tones. In high-key photography, tones that generally would have been mid-range become much brighter, near-white tones become white and white becomes, well, white. This style of lighting was originally developed for films and television, back when the technology wasn’t very good at capturing high contrast ratios. Today high key is purely an artistic decision – photographers and filmmakers choose it when they want an image or story to be upbeat, optimistic or youthful.
A common misconception is that a high-key image does not need to have a true black. And while that is sometimes true, high-key images can and often do have very small amounts of black. These very small areas of black and middle tones will prevent the image from looking washed out. That small point of black – your model’s pupils, for example, or a shadow under her hair – can mean the difference between a high-key image and one that is just plain overexposed.
How to capture a high or low-key image
A lot of people will create high-key and low-key images in post-processing, but the best way to get a successful photo with either of these lighting styles is to do it with your camera. This means either having your studio light set up for high or low-key images, or waiting until the light outdoors cooperates with you.
Studio lighting for high-key photography
A basic studio lighting set up for high-key photography consists of a key light and a fill light, with your key light two times the brightness of the fill. The background should be lit independently–preferably with two lights positioned three to five feet away at 45-degree angles. These background lights should be at least one stop brighter than your subject lighting. This will result in the blown-out background that you’re looking for in a high-key image.
High-key images can also be obtained in the studio with a pastel-colored background, though white is more common and generally simpler to work with. As for your model, you can certainly achieve a high-key effect regardless of what she’s wearing, but you may find yourself more satisfied with your work if she’s dressed in lighter colors or in white.
Natural lighting for high-key photography
You don’t need studio lighting to capture a high-key image, but you’ll need to have your bag of tricks ready. The ideal outdoor lighting situation for high-key images is flat light such as what you’ll get on an overcast day, though ideally a brighter day vs. one where, say, there’s an ominous thunderstorm on the horizon. Flat light by itself is probably not going to be enough, though, you’ll also need a reflector to fill in your shadows.
Backgrounds in outdoor settings are trickier, too, since you can’t just rely on a brightly-lit white backdrop to give you that high-key effect. Instead you need to choose a simple background that is free from dark tones and shadows. Meter for your background and then set your exposure compensation to +1. Shoot, then bracket to an exposure compensation of +2 and shoot again. You may need to go as high as +3 before you achieve the right effect – it’s really more of an art than a science, and experimentation will probably yield the best results.
Using post processing to tweak
Ideally, you don’t want to have to rely on post-processing to create a high-key image, but you can use it to improve your high-key photos or potentially create high-key images out of photos that were shot under favorable conditions but may not yet qualify as “high-key”.
There are a lot of different ways to achieve this in post-processing, but in general you’re going to be adjusting the curves in your image until you get that high-key range. Here’s one way of doing it in Photoshop, by first converting your image to black and white (though the black and white conversion is of course not required):
First desaturate your image by going to image-> adjustments-> hue/saturation. Move the saturation slider until it reaches -100. Now you have a black and white image. Next, go to Layer -> Adjustment -> Curves and play with the curves until you get the effect you’re looking for. Depending on how your subject was lit, this may be an “S” shape or a bow. Remember that you’re looking for very few blacks and midtones with lots of brighter tones and whites. You want to keep important details and not have any glaring hot spots on your subject.
At this point some photographers like to soften the image with the Gaussian blur filter. To do this, first create a duplicate layer, name it something obvious (like “blur,”) then go to Filter -> Blur -> Gaussian Blur and adjust the blur radius to somewhere in the neighborhood of four pixels. Now double click the blur layer and adjust the opacity slider down to 40 or 50 percent, until you get a softening effect that appeals to you. There are other ways to do this, of course (there always are), so if you don’t like this effect you can also set the layer blend mode to overlay, or you can add masking to the blur layer and use your eraser to bring through the areas you want sharp from the layer below.
What you don’t want
High-key does not just mean overexposed. While you are aiming for an overexposed background, you want your subject to have a good range of light tones without any badly blown-out highlights. And on the opposite end of the scale, you don’t want a lot of deep shadows, either. Ideally you will want a very small range of blacks and midtones, with most of your tones in the light or white range.
What about low-key?
You’ve probably guessed already that low-key light is the opposite of high-key light, the yin to its yang. High-key lighting focuses on light tones and whites; low-key lighting relies on shadows, deep blacks and darker tones, with very few whites and middle tones. The mood is opposite, too – while high-key lighting is hopeful and optimistic, low-key lighting is somber, mysterious and moody, dramatic or even ominous depending on the subject.
High-key images are flatter with less contrast than an image that qualifies as mid-key, which is most of the images that photographers produce. Low key images, on the other hand, tend to have a lot of contrast, with the primary impact coming from the shadows.
Studio lighting for low-key photography
A low-key studio set up is a lot simpler than a high key one. You just need a single light source and a dark or black backdrop. You may find having a reflector on hand can be helpful, too, though in many cases all you will need is that single light source. As a general rule, keep the light off of your back drop and on your subject, but other than that you have a lot of freedom as far as where you choose to place your light source.
“Natural” lighting for low-key photography
Natural or non-studio lighting is a bit trickier when you’re trying to shoot low-key. Shooting outdoors at night is always an option, though you will need a very bright light source such as a street light or the headlights of a car to obtain that low-key effect. A flashlight or a campfire could also serve as a light source. Indoors, you can also use light that filters from a bright room into a dark room through an open door.
It is technically possible to shoot a low-key image during the day, too, with a little bit of know-how. First choose a subject that is lit by the sun but is in front of a background that is in shadow. You can add your own background here if you need to with a piece of black velvet or other jet-black material, or you can simply provide the shade for the background. Now meter for the background and set your exposure compensation to underexpose by two or three stops (try both and compare). If there’s not enough contrast between your background and your subject, you can also use an off-camera flash to provide additional light.
You many need a tripod to achieve this, so make sure you have one handy whenever you’re out in search of low-key images. Capturing a low-key image during the day may mean closing your aperture and using a faster shutter speed, which may in turn mean you’ll need that tripod to avoid camera shake. At night you’ll need a tripod too, for obvious reasons, but in particular because you will want to avoid turning up your ISO. When you underexpose in low light, you may find that your images contain unwanted noise and banding – the lower your ISO, the less you will encounter this problem.
Shooting in RAW is also an option, since the RAW format captures a broader range of tones and will allow you to capture low-key potentials without having to dramatically underexpose them. With RAW, you can capture the highlights and go back to deepen the shadows in post processing.
Tweaking low-key images in post
As with high-key images, you can’t make every photo into a good low-key image. Most of the work has to be done by your camera – an image with a white or light background, for example, is going to be tough to convert to a low-key photo without some major work with the lasso and paint bucket. But an image shot under the right conditions can be made more dramatic in post processing with a few basic steps, many of which are similar (but opposite) to the steps you take to create a high-key image (these instructions are for black and white–low-key can also be color).
In Photoshop, first desaturate your image by going to image-> adjustments-> hue/saturation. Move the saturation slider until it reaches -100, just as you did when you were tweaking your high-key photo. Now you have a black and white image. Now create a brightness/contrast layer by clicking that little symbol that looks like a cross between a sun and the symbol for yin/yang. Raise both the brightness and the contrast until the image looks like you want it to. Now you can adjust the curves like you did with your high key image, only your S or bow curve will be inverted. You can also selectively lighten or darken parts of your image using the quick select tool. Just as with high-key images, a little experimentation is going to go a long way.
What you don’t want
A low-key image is not the same as an underexposed image. Underexposed images tend to be flat, with no good highlights or whites in the image. This is in fact the opposite of what you want in a low-key image. While the image does indeed rely on the shadows for its impact, low-key images need to have high contrast , which means a good white as well as plenty of deep blacks.
http://www.digital-photo-secrets.com/tip/1546/how-lighting-affects-the-mood-of-your-photos/
http://www.digital-photo-secrets.com/tip/3558/using-lighting-style-to-create-mood-high-key-and-low-key-lighting/
