creating sunstars and sunburst rays of light in your photos
- When diffraction occurs around an edge like an aperture blade, it creates two visible spikes of light 180° apart and perpendicular to the blade edge
- On a lens with an even number of blades, the diffraction spikes from opposite sides of the aperture overlap. So n-number of even blades yields n-spikes.
- With an odd number of blades, there is no overlap. N-number of odd blades yields 2n spikes.
- Newtonian telescopes give diffraction spikes from stars as a result of the struts holding the secondary mirror in place
- a circular aperture does not give a sunstar pattern but creates an Airy Disk - a bright circular spot surrounded by concentric circles that represent areas of constructive and destructive interference
- when photographing a scene with a bright light source in the scene such as the sun, or street light, many people like to shoot it with rays of light coming from it
- this is best achieved with:
- apertures f/11-22 (but remember as you stop down, although you get more defined rays of light, diffraction effects will reduce your image detail and sharpness)
- use a lens with a 9-bladed diaphragm (odd numbers are best)
- consider partly obscuring the light source
- see also:
photo/sunburst.txt · Last modified: 2018/05/20 17:01 by gary1