Hard, soft and diffused light - what is the difference?
© Bron Elektronik AG - by Urs Recher
Look at the hardness (or softness) of light is certainly the most simple and easy way to classify it. However, we can never call a certain light shaper hard or soft (with the exception of a point light source that is always hard). Depending on the sizes and the distance between the object and the light, the same light shaper can once be hard, soft or even diffused. Let’s have a closer look at these three categories:
1. Hard light:
Looking at the light of a point light source, we will see very clearly defined shadows. On a background or underground there is either light or shadow, but nothing in between, with no gradations. Even the finest details provoke a clear shadow. The structure of any object (e.g. textile, skin) is pointed out very clearly.
A very hard light source is the only one that does not change its characteristics if we vary the distance (but according to the inverse square law it does change the power). The shadows remain the same: very sharp.
Hard lights may increase the contrast of the object. The areas directly lit may be burnt while the shadows remain very dark.
The hardness of the light finally has an influence on the color saturation. Small, hard lights increase the saturation of the picture while soft, and especially diffused lights reduce it
The following light shapers can be used as hard lights:
Any open reflector like P70, P65, P45, P50, Reflector Par if used over a certain distance; a few meters and more.
Fresnel spots like Pulso Flooter, Pulso Spot 4, Fresnell spot attachment for picolite.
Optical systems like Pulso Spot 4 with 150mm optical snoot, projection attachment for picolite and Profil 15/42. Sunlite set, litestick or bare bulps (lamphead with no attachments at all).
2. Soft Light:
Average soft light sources have about the same sizes as the objects or set-ups they illuminate: Let’s say a 50 by 50 cm softbox for a narrow cropped portrait or an 80 by 140cm softbox for a full-body shot.
The shadows on the undergrounds and backgrounds are still clearly visible, even when they are not sharply defined anymore. Big parts of these shadows are graduated and a small cores hadow still exists. Small and fine details, however, do not appear. The texture of our object is now shown in lower contrast and is therefore not as clear as in hard light.
Soft light still increases the contrast of the object a little, but less than a hard one. The color saturation finally is somewhere in between the one derived from a hard light (high) and a diffused light (low). Being soft, our light source got a certain size (it is not a point anymore) and the distance from it becomes very important:
The closer we get, the bigger the light source becomes (seen from the perspective of the object or model). This means that our light becomes softer when we get closer, and harder, when we use it over larger distances.
A light of about 100 by 100cm placed at 4 meters from the model has the same hardness as a source of half the size (50 by 50 cm) at half the distance (2 meters). Due to the inverse square law, we have to expect other effects (higher contrast when placing the light closer to the object or model). When we bring the 100 by 100 cm softbox to half the distance (we will have to reduce the power by about 2 f-stops) the light will be a lot softer.
The following light shapers can be used as soft lights:
Any size softbox (choose the dimensions and the position carefully!)
Acrylic are lights such as Hazysoft, Boxlite 40 (for rather small objects), Satelite Staro.
The “soft spots” such as Satelite evolution, Minisatellite when completely focussed.
Their light is directed (not diffused), but they have a large diameter and are therefore soft. Softlight reflector P-soft.
Para 222 focussed and defocussed
3. Diffused light:
Now the light source is huge. Shadows no longer exist as the light is big enough to shine all around the object or model.
The light does not show any direction anymore, the only contrast remaining in the photograph is the contrast of the object itself.
The structure of the object’s surface is as flat as possible, almost invisible and the color saturation is heavily reduced.
The following light shapers can be used as diffused lights:
Big softboxes at short distances for rather small objects.
Indirect lights reflected by several bright walls. (These walls have to be neutral in color to avoid a color shift).
Light-tents wrapped around the object.
A good example to illustrate the difference between hard and soft shadows:
Through a very narrow opening of curtains, daylight is falling into this hotel room. Horizontally, the opening is only a few centimeters wide – the corresponding shadows are very hard. The vertical shadows, however, are very soft because the curtains let some light in from the ceiling to the floor.
In the studio, this effect can be simulated with narrow Striplites like the Striplite 120 or, with some limitations, a Pulsoflex EM 30x110 and EM 40x155.
This text is the beginning of the first chapter of Urs Recher’s book “Light Architecture ”.