"Candelas Lumens and Lux" introduction to lighting  terms and calculations
"Candelas Lumens and Lux" introduction to lighting  terms and calculations




Type A, Type B, Type C, .IES IESNA Photometry Files

IESNA photometry files have the extension .IES and have three main types, A B and C:

Type A These files are used for car headlights etc. A for Automotive is an easy way to remember it. The polar axis coincides with the major axuis of the luminaire, i.e. where the headlight is pointing.
Type B These files are used for floodlights. In other words these are VH photometries.
Type C These files are used for internal lighting and use the C-Gamma system. These are by far the most populare file type.


For some twisted logic of ancient DOS era programming the type letter is represented by a number within the file. And as a further show of contrariness the numbers 1 2 3 represent the letters C B A:

Click here for a method of converting from Type B to Type C IESNA files.

For more on C-Gamma vs VH photometries:

"Candelas Lumens and Lux" book cover

The book is designed for both beginners who intend to go deeper into the subject later, and professionals (maybe from other fields) who need to know at least the basic scientific principals and terminology.

Where To Buy "Candelas Lumens and Lux" by Owen F. Ransen



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