Texture and form

Learning goal

You will be able to set up the light that makes a surface look touchable in a photo. You will tell texture, the small roughness of a surface, apart from form, the whole volume of an object; you will explain how the angle at which light reaches a surface brings out texture and how it flattens it; knowing that light grazing a surface will darken the surface while raising its texture, you will adjust the exposure for it; you will see that a small, hard source brings texture forward and a large, soft source brings form forward; and you will know that side light also brings out the texture of the skin on every skin, and that this is a choice, not a flaw or a virtue.

The question

In a pottery workshop, you are photographing clay jugs lined up on shelves. The light falls on the jugs straight from the front, from the big window opposite. In the photo the jugs are flat, like brown silhouettes from a cookie cutter; none of the clay's roughness, the potter's fingerprints or the fine rings the wheel left can be seen. Yet when you run your hand over the jug, you can feel them all.

Can we touch a photograph? Not with our hand, but with our eye, maybe. What makes us feel a surface's roughness and an object's volume in a photo is the angle of the light. In this lesson we will talk about the light that brings out texture and form, where this light needs to come from, and why it sometimes raises a surface and sometimes flattens it.

Context

In Lesson 5.2 we saw how a face changes when light comes to it from different directions, and said that light from the front flattens while light from the side adds depth. In Lesson 5.3 we also talked about how the apparent size of the source decides the hardness of the light. This lesson applies those two pieces of knowledge to the smallest detail of a surface and to the whole volume of an object.

Texture and form are the two ways a photograph can build a three-dimensional world on a two-dimensional surface. Both come from tonal difference: the side of a surface facing the light stays bright, the side away from the light stays dark. What builds or erases this difference is where the light comes from and how large it is.

Simple explanation

What is the difference between texture and form?

Texture is the small-scale roughness of a surface: the bumps of a stone wall, the weave of a fabric, the cracks in a bread crust, the splits in tree bark. Form, on the other hand, is the whole volume of an object: the roundness of a jug, the cheekbones of a face, the slope of a hill. Texture lives on the surface, form in the body of the object.

The scale of the tonal difference that shows them in a photo is different too. Texture is shown by thousands of small bright and dark specks, formed when one side of each small bump stays bright and the other in shadow. Form is shown by a tonal gradation that slowly darkens from the side of the object facing the light toward its back: the jug's shoulder facing the light is bright, and the surface turning toward the back grows darker and darker. A photo can show texture and hide form, or do the opposite.

How does the angle of the light bring out texture?

The strength of the light falling on a surface depends on the angle at which it reaches that surface, its angle of incidence. When light falls perpendicular to a surface, it gives the strongest illumination; as the angle grows more slanted, the same light spreads over a wider area of the surface and the brightness drops. In light from the front, all the small bumps of a surface face the light at more or less the same angle; they all stay at the same brightness and the texture disappears.

If the light comes from the side of the surface, almost parallel to it, things change. This light is called grazing light. The small face of each bump turned toward the light is lit, the face behind it stays in shadow, and the bump itself casts a small shadow behind it. The surface splits into thousands of small bright and dark specks; the texture rises. But this has a cost: because the light falls slanted on the surface, the surface's overall brightness drops. When shooting in grazing light, know that the surface darkens, and adjust the exposure for it.

What does the size of the source change?

A source whose apparent size is small, like the sun, a bare bulb or a small flash, casts sharp-edged shadows. Every small shadow of the texture is sharp and dark; stone walls, clay and tree bark take their most distinct form in such light. A large source, on the other hand, like a big window, a cloudy sky or a soft light box, softens shadows. The small shadows blend into each other and the texture settles.

But the large source shows form another way. It wraps around the object and builds a wide, soft tonal transition stretching from its bright shoulder to its shaded back; the roundness of a jug and the volume of a face read in this transition. In short, a small source tends to bring texture forward, a large source form. That is why a product photographer chooses a small side light to show the texture of a leather bag, and a large soft light to show the curve of a vase.

What do the time of day and skin change?

The sun is low in the morning and evening and falls grazing onto the ground, roads and fields; footprints in the sand and the lines of a plowed field appear at these hours. At noon, on the other hand, the sun is high and falls perpendicular to the ground, flattening texture. But the same noon sun falls grazing from above onto a vertical wall; the texture of a stone facade can be more distinct at noon. The question to ask for texture isn't what time of day it is, but at what angle the light reaches that surface.

Human skin is a surface too. Side light, whatever the skin's color, brings out pores, wrinkles, beard and scars. On light skin this texture usually reads through small shadows, and on shiny, dark skin usually through small glints that reflect the light. If you want to tell of the years in an old craftsman's hands, this light is exactly the light you are looking for; if you want to show a face soft and calm, light from the front or from a large source suits better. Neither is a flaw or a virtue; it is a choice made according to what you want to tell.

Visual evidence

You go back to the workshop. You ask the potter, an elderly, dark-skinned man, to move one of the biggest jugs next to the window, to a place where the light will come to it straight from the side, almost parallel to its surface. The jug's edge facing the window glows, its back is in shadow; the wheel rings on the clay have turned into thin bright and dark lines, and the potter's fingerprints can be made out like small hollows. Because the surface has darkened, you open the exposure by a stop.

Then you come closer to the potter's hands holding the jug. In the same side light, the wrinkles on the knuckles of his fingers, the clay under his nails and the small glints on his skin are sharp; the years of work read in his hands. When you take the jug back opposite the window, into light from the front, the same hands and the same jug flatten again. The same light source, the same object; what changed was the angle at which the light reached the surface.

Common mistakes

Summary

Texture is the small roughness of a surface, form the whole volume of an object; both show through tonal difference. Light from the front flattens texture; light grazing the surface raises texture by giving each bump a bright face and a shadow, but darkens the surface. A small, hard source brings texture forward, a large, soft source form; side light also brings out the texture of the skin on every skin, and showing or softening it is a choice made according to what is to be told.

Mini assignment

In this assignment you will photograph the same object with light coming from different angles, and compare texture and form.

1. Photograph a textured object, a loaf of bread, a stone or a knitted sweater, first with light straight from the front, then with light straight from the side.
2. Photograph the same object in side light, first with a bare lamp, then with a window or a lamp behind a white curtain, and look at how the texture changes.
3. Photograph a round object, a jug or a fruit, with a large, soft source, and look at the tonal transition.
4. Photograph someone's hands or face first with side light, then with soft light from the front; note which one adds years to the face, and which one calm.

Check yourself

• In the frame you took with side light, can you feel the texture with your eye?
• Did you notice the surface darkening in grazing light and adjust the exposure?
• Do the two frames of the hands or face, regardless of skin tone, tell two different things?

Glossary

Mini quiz

1. Why does light from the front hide the texture of a stone wall?

• A) Because all the bumps face the light at more or less the same angle, they stay at the same brightness
• B) Because light from the front is always weaker
• C) Because stone doesn't reflect light
• D) Because the camera can't focus in light from the front

2. When shooting in grazing light, what do you watch for with exposure?

• A) Stopping down the exposure because the surface is brighter
• B) The exposure not changing at all
• C) Knowing that the surface darkens because the light falls slanted, and adjusting the exposure
• D) Setting ISO to its lowest

3. Which source is better for showing the roundness, that is the form, of a vase?

• A) A small bare bulb
• B) A large, soft source
• C) A small flash from straight behind
• D) The source doesn't matter

4. What do you do to show the wrinkles in an old craftsman's hands distinctly, regardless of his dark or light skin?

• A) Give the light straight from the front, from a large source
• B) Give the light from overhead
• C) Stop the exposure down two stops
• D) Give the light from the side, so it comes slanted onto the surface of the hands

Answers

1. A — In light from the front, none of the bumps stays brighter or more shaded than the others; without tonal difference, texture isn't seen.
2. C — Light falling slanted on a surface spreads the same strength over a wider area; the surface darkens and the exposure should be opened accordingly.
3. B — A large source wraps around the object and builds a wide, soft tonal transition that shows volume.
4. D — Side light gives wrinkles bright and shaded faces; on light skin they read through shadow, on dark, shiny skin through glints.

Summary card

• Texture lives on the surface, form in the body; both show through tonal difference.
• Light from the front flattens texture; grazing light raises it but darkens the surface.
• A small, hard source brings texture forward, a large, soft source form.
• For texture, look not at the hour but at the angle at which light reaches the surface.
• Side light shows the skin's texture on every skin; showing or softening it is a choice.

Bridge to the next lesson

The wheel rings of the jug, the potter's hands, the roughness of a stone wall; everything we saw in this lesson could be read without color too, because it all came from the difference between light and dark. Sometimes the clay's brown, the potter's blue apron and the window's green frame even drew the eye away from the texture. What happens to a photo when you let go of color entirely, and when should you think of a frame in black and white? The next lesson talks about black and white not as a filter, but as a way of looking.