It’s now November and I’m beginning the section on Light – so much more to learn. I started a Vocabulary section back in early March and added to it in April I believe, so there are a few more terminologies that I should add now. These are all related to light. As I work through the light section of this module, I will come back and add to this posting.
- transmission – light that has passed through a subject, e.g. clear glass
- refraction – the bending of light rays as the light passes through a subject from one material to another
- diffuse transmission – the scattering of light waves in random directions, e.g. when light hits thin paper. An object that aids diffuse transmission would be a diffuser cap for a flashgun. Light is absorbed, reflected and transmitted.
- absorption – light that is never seen again (absorbed by the subject and emitted as a heat source). An example of a light absorbing material would be black velvet.
- reflection – light that strikes a subject and bounces off
- diffuse reflection – same brightness regardless of the angle of view. Light is reflected equally in all directions. White things produce diffuse reflection.
- inverse square law – intensity of light is inversely proportional to the square of the distance. For a visual (and better) explanation check out this video by Mark Wallace.
- direct reflections – a reflection of the original light source
- the angle of incidence = the angle of reflectance – light rays bounce off smooth surfaces at the same angle that they hit it.
- family of angles – direct reflection are only visible to the eye within a limited range of angles – basically the angles that produce direction reflection. Important because it determines where we should place our light source.
- polarized direct reflection – a reflection that is half as dim as a direct reflection due to the absorption by the polarizer.
- perspective distortion – when viewing a three dimensional subject where the part further away appears smaller than the part that is closer to the viewer, which in turn appears larger.
- tonal variation – the light and dark areas in the subject. Ideal tonal variation should include a partly shadowed side, a shadowed side and a highlighted side.
Hunter, Fil et al, (2012). Light—Science & Magic An Introduction to Photographic Lighting. 4th ed. Oxford: Focal Press
Wallace, Mark (2011) Digital Photography 1 on 1: Episode 59: Inverse Square Law: Adorama Photography TV [online, webcast]. Adorama TV. Available from: https://www.youtube.com/watch?v=f5BIvSBjvLg. 12 mins 15 secs. (accessed 12 November, 2014)