Guide: Simple and Full Article About Light in Photography

Light in photography is a fundamental topic (artificial light, reflected light, etc.). For photographers who have decided to go into manual mode or are faced the need to adjust the light: you need to understand how the light works and how the camera reads it. Therefore, let’s talk about light in photography from the point of view of both – theory and practice.

Aperture and what it is all about

If we do not go into the technical details, wide aperture of the lens lets more light in. And wider we make the aperture, the lower our F value on the lens. This means that F/1.4 is an open aperture and a wide aperture. And F/11 is a closed aperture.

The wider the aperture, the less we can use ISO or shutter speed (exposure time – the time when the camera takes a picture). This is because more light enters the camera. When we get a lot of light, we can put very short shutter speeds. It is important to understand that the aperture, ISO and shutter speed are a “pyramid“. The higher the ISO, the more closed the aperture or shorter shutter speed we can use. The longer the shutter speed, the lower the ISO and/or the more closed the aperture.

To understand how correct the exposure is (darker or vice versa lighter than necessary), use the histogram and the exposure level indicator. Both functions can be enabled on almost any camera. For a better understanding of process, I recommend you read the documentation (manual) for your camera. There you will find proper information about the different exposure meter modes and other useful features available on your camera.

How does the aperture affect the picture?

It’s pretty simple, the wider the aperture, the more the subject in focus will be separated from the background and the more obvious the bokeh (although it depends on the distance of the model from the background and the point of the camera), that is, the object or its fragment will be clear, and everything else will be blurred. Here we come to the territory of the term “Depth of field” (I will write an article about this, but for now we are dealing with the aperture).

You may think: the more closed aperture and the higher the F value – the sharper the picture as a result. But it’s not true. In fact, the maximum sharpness of the frame is received on a full-frame camera at a value of F/8, and then there is a degradation of quality. For this interesting thing we are obliged to diffraction of waves, but in order not to go into concepts of optics (we do not need to understand them, in fact it is only important to know how it affects the photo), we will decide that the working aperture that allows to get high quality and sharpness is in the range of F/8 – F/11.

Light in photography: key light, fill and rim (classic three-point lighting)

Depending on the purpose that light serves in photography, it can be classified by direction in relation to the object (or model). If the main light hits the model from the front/front-side, then it is considered to be a key light – it’s the main light. It creates a lighting pattern.

If we add another light source to fill shadow on the model, this is a fill light. Fill light does not affect the lighting pattern, but only brightens the shadows.

Okay, let’s imagine: we placed a key light and added a fill light to it. That’s enough for a good photo- the model is well lit, there are no wasted details in the shadows. But the photo lacks some accent, maybe you want to separate the model from the background or just create a more “commercial” look..

And then we add another light source – a rim light, sometimes it is called a backlight or a kicker. It is placed at the back, slightly on the side of the model, so that it creates a contour of light. The second option is to put a light on top behind the model to illuminate the hairline. If we light the hair from above that light is called hair light.

When we use all three light sources – key, fill and rim – this scheme is called three-point lighting. This type of lighting is very popular and it is loved by photographers and filmmakers.

“Qualitative” classification of light in photography: direct light, reflected light and diffused light

Imagine that we are photographing a model on the street, the sun is shining brightly. The model turns to the sun, you close the aperture and take a photo. Such light, the direct light of the sun, is called direct.

If the model moves a little into the shadow, so that the sun does not affect on her directly, for example, the model stands next to a white wall (the light from which will illuminate the model), then such light is considered reflected. This is why lightdisks, or reflectors are needed – to bounce the light.

If we like direct sunlight, but there is not a cloud in the sky, the model squints and the picture turns out to be too contrasty, but we have a diffuser or screen (a frame with a white fabric stretched over it). If we pass light through such a filter (in the form of a diffuser), this is diffused light. Or we can go somewhere near a white wall, move model away from direct sunlight and use only the light reflected from the wall as a key light.

In this example, bright direct sunlight is a source of hard light, and diffused light is a source of soft light. I talk more about the hardness and softness of light below (section modifiers).

Tricky question: “correct” placement of the reflector (lightdisk) and light in photography

How to place the reflector correctly? Such a question will ask a person who does not yet know the basics of lighting. Someone says that it should be placed lower, someone says that is higher… Utter confusion!

It’s really simple. In portrait photography, it is undesirable to have a key light from below. In general, the light from below is horror lighting (in horror films). But!..

Curiously enough, in beauty shooting such light from below is often uses with the “upper” key light. That is, one light is placed above the level of the model’s head, and the second – at chest level. This is called “clamshell” lighting.

This means that questions about the correct point of the reflector is incorrect. The reflector can be placed at the bottom and top depending on other settings. Just remember the “horror lighting” and don’t use it where you don’t need to.

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Difference between light and shadow or light ratio in the photography

First, let’s take a look at the “Tone system“, on the example of a sphere, we see how the volume is built with the help of five stages of tone. If we squint our eyes, then we see only two tones at all – light and shadow.

As photographers, we will immediately think: here is a key light on the top left illuminates the sphere, and the white surface of the table reflects light (this is reflected light) and fills the shadow on the sphere .

Note that shadow and light have completely different illumination (which is generally understandable). And now let’s try to imagine why we need this information. It’s that simple! To successfully build volume in a photo, we need to use this tonal range.

In photography the difference between the illumination of “light” and “shadow” (tonal difference) is explained by the term “Lighting ratio“. When the light side of the face, for example, is three times brighter than the shadow side, then this Lighting ratio will be 3:1.

Light meters (exposure meters) are used to measure illumination. By the way, it is quite expensive. In general, the exposure meter is needed for the correct selection of the light level (applied to pulsed light in the “stops“, read about the stops below in the article) – to set the correct exposure. Usually people uses flashmeters when shooting on film.

What can we learn from this information?
In short: there should be a difference between light and shadow, at least 2:1, but usually no more than 5:1 (although there are exceptions). Typical values are usually 3:1 and 2:1.

Quantity and quality of light in photography: distance from the light source

In studio photography, when using flashes, a similar rule works. The light source has a certain distance from the object, which allows you to receive high-quality light, and then the correct colors and tones will be seen in the photo.

For example, when installing a light source at a distance of one meter from the model, 100% of all light will fall on the model – this is the point of the highest light intensity. And to reduce the amount of light in half you need to put it from the model by two meters? And here lies a serious mistake, because the physics of light says completely different rules, in this case the law of inverse squares begins to work and it says:
the intensity of light = 1 divided by the distance of light from the object squared.

In our case we divide 1 by (2 m squared = 4 m) = 1/4 ! Simply, if we remove the light further twice, namely from a distance of one meter to a distance of 2 meters from the object, then instead of 100% of the light we will get only 25%. And thus, by moving the source from the starting point by a meter, we lost 75% of the light, and not 50% as it might seem. Once again – we removed the light twice as far – we got 4 times less light.

Thus, shifting the light by 3 meters from the model, we will get only 11%, by 4 – 6%, 5 – 4%, 6 – 2.8% and so on according to the formula. As you probably noticed, the further the light is, the less the intensity drops. If at the beginning we lost as much as 75% of the light, then we lose 14%, then 5%, then 2%, then 1.2% and so on.

Light intensity = 1 / distance squared from the light source to the object

What does the distance of the light source from the model affect? If the light is too close, then there is a risk of getting overlight, which will be impossible to correct. And if the distance is too large, then we have a risk getting “dirty” colors in the photo and losing the clean colors and tones. In fact, in painting and in photography there are no right and wrong colors, clean pure colors are certainly liked by people, but the truth is this – pure colors look naive, often cheap, their abundance in the frame does not add sophistication and artistic intent is more important, and many artists and photographers skillfully use both “clean” and “dirty” colors. For now, let’s agree that it is much more important not to spoil the RAW.

Stop – what is it?

Okay, that’s more or less clear. But besides, the photographer can say “Raise the light by two stops” or “Decrease by one stop”. On the lens (in manual mode) or in the settings of the camera, there is an F-stop scale from 1.4 to 22 (depending on the model and class of lens). The value of F/2.8 is followed by the value of F/4 – between them the difference is 1 stop. But how do you know what exactly changes when you switch settings? In fact, on F/2.8 there are TWICE as much light passes trough lens, than on F/4. When we change the aperture from F/5.6 to F/ 2.8 – we open the aperture by two stops, but at the same time we increase the amount of light passing into the camera FOUR times.

Modern full-frame cameras have about 12 stops of dynamic range. But in digital – for publication on the Internet, all these 12 stops are compressed into 8.

Soft and hard light in photography: properties and modifiers

If we talk about the quality of light, then first of all we should mention the hardness and softness. Briefly, soft light gives a smooth transition to the shadows, and hard – a sharp shadow line. But that’s not all, hard light perfectly emphasizes the texture, makes bright highlights and deep shadows – such light is often used in advertising of the luxury segment and fashion. But soft light reduce the texture, makes gradients smooth.

The larger the light source and the closer it is – the softer the light, the smaller and further – the harder the light. But soft light, even at a distance, does not become hard, and hard near does not become soft. Only a part of the properties is lost.

Hard light is produced by bare bulb, reflectors, magnum reflectors, a silver beauty dish, the midday bright light of the sun on a cloudless day. And soft light is produced by: various softboxes, octoboxes, a beauty dish with a diffuser, daylight in cloudy weather.

Hard light sources are not suitable for shooting Senior models, if there is no goal to emphasize the texture of the skin and wrinkles.

In this article, we discussed the concept of Light in Photography: aperture, the change in light intensity, got acquainted with how diffraction affects the picture and made conclusions and learned what the stops are.