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Solid Angles

Solid Angles

Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 2014/07/26 Do you suffer from math anxiety? A surprising number of us do (e.g., Wigfield 1988). I would tell you the exact numbers, but you would need to understand...

Solar Illumination

Solar Illumination

Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.    Published: 2015/01/21 Lighting design is based in part on the reasonable assumption that photometric units have precise definitions. The candela, for example, has a precise...

Seeing Ultraviolet

Seeing Ultraviolet

Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 2015/10/26 UPDATE 15/11/08 - The following text briefly notes that some people can see near-ultraviolet radiation following cataract surgery due to the UV transmittance of...

Rethinking the Photometric Data File Format

Rethinking the Photometric Data File Format

Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2017/03/01  If you perform lighting design calculations today, you can thank the efforts of the IES Computer Committee (IESCC) some thirty years ago. Its members recognized an...

In Search of Luminance

In Search of Luminance

Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2014/11/18 The IES Lighting Handbook, Tenth Edition (IES 2010), describes luminance as "perhaps the most important quantity in lighting design and illuminating engineering." This is...