Shadows and Form
Written by Abin Alex and Anu Joseph.
Abstract
A practical guide to shadows and form: umbra and penumbra, how source size changes a shadow, how light reveals form, the five values and the named elements of light on a form, with three diagrams and two tables.
Keywords: shadows, umbra, penumbra, light reveals form, five values, terminator, core shadow, cast shadow, highlight
How do shadows form?
Short answer. A shadow forms where an opaque object blocks the source. It is darker, but some light always reaches it.
- A shadow occurs when an object blocks a light source from reaching an area. Shadows are darker, but there is always some light that reaches them. We can still see the colour of a shadowed object even when that colour is very dark.
- Shadows have two parts. The umbra is the region of complete shadow, which receives no light. The penumbra is the diffuse region that receives light from part of the source. In a solar eclipse the umbra gives a total eclipse and the penumbra a partial one.
- The direction of a shadow depends on where the light is. The same rule makes the moon show a different shape, or phase, every few nights.
Hold a pencil over white paper under a lamp. Find the dark centre and the soft edge of its shadow.
On a set the penumbra edge is controlled by the size and distance of the light.
Cham tipLook for the two parts of a shadow, the dark core and the soft edge.
Cham taskDraw a shadow and mark the umbra and the penumbra.
Check yourself: Which part of a shadow receives no light?
The umbra.
How does source size change a shadow?
Short answer. A bigger source makes a smaller umbra and a wider penumbra. A point source makes a sharp image.
- A bigger light source gives a smaller umbra and a wider penumbra. With a wide source two shadows can be seen, and shifting the background shows the penumbra.
- A smaller source gives a shadow with a sharper edge. If the source is a point, a sharp, well defined shadow forms on the background. If the source is big, a blurred shadow forms (Figure 1).
- Why can we not see a bird shadow high in the sky? The light source is much larger than the bird, so the umbra forms very close to the bird and the shadow disappears. A very large source reduces the umbra until the effect is shadowless.
- In the book the same fact is stated in terms of the sharpness of the shadow edge. A hard shadow has a clearly defined edge, and a soft shadow has no clearly defined edge (Hunter and Fuqua, 1997, pp. 16-17). For single lights the size of the source is the main influence on this (Hunter and Fuqua, 1997, p. 18).
Light a pencil with a bare bulb and then with the same bulb behind tracing paper. Compare the shadow edges.
A larger source wraps around the actor and softens every shadow on the face.
Cham tipThe larger the source seen from the subject, the wider the penumbra.
Cham taskPhotograph one shadow with a small and a large source and measure the width of the penumbra.
Check yourself: What does a larger source do to the penumbra?
It makes it wider.
How does light reveal form?
Short answer. Highlight and shading turn a shape into a solid, and a cast shadow anchors it on a plane.
- We cannot see form without light. To draw or photograph anything convincingly, you need to understand how light and shadow work together to reveal the forms we see.
- Highlight and shading convert a flat shape into a solid. A cast shadow anchors the solid on a plane and strengthens the illusion of a third dimension in a two dimensional picture.
- A photograph is flat, like a drawing. The depth of a real subject only survives in the picture as differences in tone (Child and Galer, 2008, pp. 18-19). Dark shadow beside bright highlight is the cue that tells the brain the scene has three dimensions, so the photographer must protect it.
Photograph a ball under flat light and then under side light. Compare how round it looks.
Directors of photography shape faces with shadow. Without tonal difference the face is flat.
Cham tipNo tonal difference means no depth.
Cham taskPhotograph one sphere in flat light and in side light and describe the difference in form.
Check yourself: What anchors a solid object on a plane?
The cast shadow.
What are the five values on a subject?
Short answer. White, highlight, midtone, shadow and dark.
- Light travels straight, so a curved surface turns away from it gradually, and the brightness falls in five readable steps (Figure 2). Learn to name them and you can describe any photograph. Table 1 defines each value.
- Most beginners see only light and dark. The midtone is where the subject actually lives, so read these five on a face and you can light anything.
| Value | What it is |
|---|---|
| White | The purest light, usually a direct reflection of the source, the specular highlight |
| Highlight | The brightly lit area around the white point, showing the true colour under strong light |
| Midtone | The average value where the surface begins to turn away, with the actual colour and texture |
| Shadow | Where light begins to fade as the surface turns further away, a soft shadow on the object |
| Dark | The deepest areas where light is completely blocked, such as cracks, crevices and the cast shadow on the ground |
Table 1. The five values explained.
Point to the five values on a face or an egg under one light.
On a set the range from white to dark is judged on the monitor and the waveform.
Cham tipLook for the midtone first.
Cham taskLabel the five values on a photograph of a face.
Check yourself: Where does the subject colour and texture live?
In the midtone.
What are the elements of light on a form?
Short answer. Highlight, form light, terminator, form shadow, core shadow, halftones, reflected light, occlusion shadow and cast shadow.
- Every form lit by one light shows the same named parts (Figure 3). Table 2 gives each term.
- Under direct light you see the centre light, the highlight, the form light with halftones, the terminator, the form shadow, the core shadow, reflected light, occlusion shadows and the cast shadow. Under diffused light the form light, the form shadow, the halftones and the reflected light remain, and the edges between them are gradual (Grey, 2004, p. 12).
- Portrait photographers name three zones on a lit face: the specular highlight, where the source reflects straight into the lens, the diffused highlight, which shows colour and form, and the transition area into shadow. A narrow transition means hard light and a wide one means soft light (Grey, 2004, p. 12).
| Term | Meaning |
|---|---|
| Centre light | The area that faces most directly towards the light source |
| Highlight | The reflection of the light source |
| Form light | The part that receives direct light |
| Terminator | The line that divides form light and form shadow |
| Occlusion shadows | Created where two surfaces get close to each other |
| Cast shadow | The terminator projected on the ground |
| Penumbra | The softness around the edge of the cast shadow |
| Form shadow | The part that is in shadow |
| Core shadow | Created as reflected light loses strength |
| Halftones | Form light divided into steps that darken as the form turns away |
| Reflected light | Light that brightens the form shadow |
Table 2. The elements of light.
Light an egg or a ball with one lamp and name every element you can see.
These names are the vocabulary of lighting talk on set.
Cham tipFind the terminator first. Everything else sits on either side of it.
Cham taskPhotograph a sphere under direct and diffused light and label the elements on both.
Check yourself: What is the terminator?
The line that divides form light and form shadow.
How does source size change the highlight?
Short answer. A highlight is the reflection of the source, so a small source makes a small highlight and a large source makes a large one.
- A highlight is the reflection of the light source and is visible only on reflective materials (Grey, 2004, p. 12). A highlight is any spot brighter than its surroundings, and it can be pure white or any colour whose value is brighter than the values around it.
- The size of the highlight depends on the size of the source. A small source gives small, hard highlights on glass bottles, and a large source gives large highlights (Hunter and Fuqua, 1997, pp. 19-20).
Photograph a glass bottle with a small lamp and then with a large softbox. Compare the highlight.
The shape of a highlight in an eye or on glass shows the source used.
Cham tipThe highlight is a picture of your light.
Cham taskShoot a glass bottle with two source sizes and describe both highlights.
Check yourself: What does a highlight show?
The reflection of the light source.
Questions beginners ask
What is umbra and penumbra?
The umbra is the region of complete shadow and the penumbra is the soft region that receives light from part of the source.
What does a bigger light source do to a shadow?
It makes the umbra smaller and the penumbra wider, so the shadow edge is softer.
What are the five values in photography?
White, highlight, midtone, shadow and dark.
What is the terminator?
The line that divides form light from form shadow on a lit form.
How does light reveal form?
Highlight and shading make a shape look solid, and the cast shadow anchors it to a surface.
References
- Child, J. and Galer, M. (2008) Photographic lighting: essential skills. 4th edn. Oxford: Focal Press.
- Grey, C. (2004) Master lighting guide for portrait photographers. Buffalo, NY: Amherst Media.
- Hunter, F. and Fuqua, P. (1997) Light: science and magic: an introduction to photographic lighting. 2nd edn. Boston: Focal Press.
Further reading
- Hirsch, R. (2008) Light and lens: photography in the digital age. Burlington, MA: Focal Press.
- Marr, D. (2004) Beginner's guide to photographic lighting: techniques for success in the studio or on location. Buffalo, NY: Amherst Media.
How to cite this guide. Alex, A., & Joseph, A. (2026). Shadows and form: A guide for photographers and cinematographers. Creative Hut Academy. https://creativehut.org/library/shadows-and-form/
Make this your craft at Creative Hut Academy
Creative Hut Academy in Mattakkara, Kottayam, Kerala teaches photography, cinematography, editing, sound and AI filmmaking in one-year residential diplomas. Students come from across India.
Want to talk? Message us on WhatsApp, or ask Cham, our AI mentor, a study doubt.