Understanding Photographic Technology
Photographic Technology courses available through ACS Distance Education. Click here for more information.

Understanding Photographic Technology

Photographic Technology involves understanding the physical and chemical processes that result in the capturing of an image either on film or an electronic recording (ie. Digital). Both methods share technology; and whilst Digital has become the preferred option for many people, understanding film can also provide insights into digital.

Digital and film photography. So different, yet so much the same.



Light Interacts with Matter

When particles of light fall on any matter (solid, liquid or gas), those particles react in one or all of the following ways:

  • Reflection
  • Absorption
  • Transmission


*Can be diffuse or direct

*Direct reflection does not scatter light (eg. like reflection in a mirror), hence the reflected image is not distorted in any way. This is also called specular reflection.

*Diffuse reflection can reflect light in a number of different directions (ie. scatter the light).

*Diffuse reflection may reflect light at the same intensity (ie. luminescence) in all directions, or it may be more intense in one direction and less in another.

*Reflection can be a mix of both diffuse & direct (ie. mixed reflection).

*Reflected light can be part or fully polarized.Ordinary light travels in a straight line but has a wave like vibration acting in all perpendicular directions to the direction of travel.Most surfaces which reflect light will restrict vibrations in one direction.The resulting light is polarized.Fact:light falling on glass at an angle of about 56° to the perpendicular of a surface will be almost totally polarized).The valuable practical application for photographers who recognise this effect is that undesirable reflections can be reduced or eliminated by use of a polarizing filter.


Light which is absorbed disappears as light, changing into some other form of energy (frequently heat). It can change into other forms though (eg. When it is absorbed into green tissues of a plant it changes into chemical energy -in effect, the light energy becomes locked into chemicals produced by plant photosynthesis. In this way, a plant stores energy, and at a later stage, can break down the chemical bonds releasing that chemical for use in the plant).


When light passes through a solid object; this is transmission. When light transmits without changing course (ie. no scatter), it is direct transmission. This can occur through clear glass. If light is scattered, we say it is diffuse transmission. Mixed transmission (a combination of both) may occur.

Transmitted light can also be polarised by filters coated with particular crystal or organic coatings


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