At first soft and hard light seems like red and purple music – the word just don’t make sense, but soft and hard light are actually very important and simple concepts in photography.
In a nutshell soft light is a light that makes shadows with softs edges and a gentle gradient change from light to shade while hard light makes shadows with hard well defined edges.
To help demonstrate the effect of hard and soft light I’ve taken two pictures of my friendly neighborhood lion (that made its first appearance in the aperture post), for the first picture I’ve put the lion on a tripod near a window and just took a shot on Av mode – we will talk abut why windows give soft light below, you can see the very pleasing change from the brighter right side to the darker left side and that the left is well lit even with just one light source on the right side.
For the second picture, I’ve put the lion on a pillow and used a flash on the far right, we will talk about why a far a away flash is considered hard light in a second, you can see the left side of the head is dark, the fast light transition on the face and the sharp line the shadow makes on the pillow in the bottom right and top left sides of the picture.
If you look at the texture of the lion’s fabric you can see that in the soft light picture it looks, well, softer, everything looks smother and small features (like the seem in the middle of the lion’s body) are visible but look small and insignificant – this is why this is a very good portrait setup, it makes skin look softer and smother and is generally a very flattering light.
The hard light picture on the other hand makes the lion seem rougher, small features are more exaggerated (the seem in the middle of the body is now a very clear dark line) – this is why this light does not generally make people look good, but it does add drama and can work for photographing people if you want that dramatic look and don’t want to make our subject look like a fashion model.
Now, how do we create soft or hard light? simple, the bigger the light is and the closer it is to the subject the softer the light, let me explain:
If we have a light source that is a single point, like the left diagram below, there are areas that are lit and areas that are completely dark – all the light comes from a single source and each ray of light can only hit one thing before it’s reflected back – but if we make the light source bigger, like the right side of the diagram, not all the light comes from a single point, and there are areas where light from one side of the source is blocked but is still lit by the other side – those are the areas of soft shadows.
As we make the light source larger the soft shadow areas grow until, if the light source is very large compared to the subject, the dark area disappears completely, in the diagram below we see a much larger light source at the same distance as the previous diagram.
And finally, in the next and final diagram, we see a light source of the same size closer or farther away and we see that the farther we take the light source the smaller the soft shadow areas become and the light get’s closer to a point light source, that is why the sun, while huge, is a very hard light source.
So, the sun is a hard light source because it’s far away and our flash is a hard light source because it’s small – so where do we find soft light?
We get soft light by reflecting or diffusing light on some surface, for example, light outside on a cloudy day is soft because the light “spreads out” on the clouds and the entire sky becomes one large light source, also, during sunrise and sunset the sun is lower on the horizon and so the light passes trough more of the atmosphere resulting in a softer light.
Window light is also soft because the entire window acts as a light source and so is light reflected from any large surface.
For flashes, aiming the flash at a wall of the ceiling softens the light because the light source is now a big piece of the wall instead of the tiny flash bulb – also, there are a lot “light modifiers” you can put between the flash and subject to soften the light, the most common is without a doubt the umbrella (instead of the flash head the entire umbrella is the light source – making it much bigger).
Hard light is also much more prone to reflections and specular highlights than soft light.
It’s important to mention that when we are talking about small and large lights we mean in relation to the subject, your camera’s flash is tiny when photographing a person from across the room but quite large for a close-up picture of an insect.
So, to summarize, here’s a table of the properties of soft and hard light and two pictures of a red plastic dinosaur, taken with the same camera settings, the right side was lit with a bare flash far away (hard light) and the left side with a small softbox right out of frame (soft light) – click image for larger version:
|Soft light||Hard Light|
|Shadows||Soft edges||Sharp edges|
|Reflections||Less reflections||More reflections|
|Light Source||Big and close||Small or far|
|Good for||Beauty shoots||Dramatic pictures|