Classifying Luminaire Cutoff and Glare Metrics
A technical guide to the BUG rating system and luminaire cutoff classifications, explaining how to evaluate glare and light trespass using ANSI/IES TM-15-20.
11 min read
Photometrics
Photometrics Articles
18 articles on photometrics for professionals in the lighting industry.
Other Topics
Measuring Luminaire Luminous Flux in Integrating Spheres
Technical overview of integrating sphere testing for measuring total luminous flux, spectral distribution, and efficacy of LED products per LM-79.
11 min read
Understanding IES File Polar Candela Plots
Explains how to interpret the polar curves in an IES file to determine beam symmetry and intensity distribution.
13 min read
Using Scotopic/Photopic (S/P) Ratios in LED Street Lighting
How S/P ratios affect perceived street light brightness. Calculate visually effective lumens for LED fixtures to improve night visibility and energy savings
12 min read
IES Files Explained: What They Are and How Lighting Designers Use Them
A technical deep-dive into IES photometric data files: their structure, how they're created, how to import them, and what to watch for in quality.
9 min read
Photometrics
Featured
What Is a Photometric Study? A Complete Guide for Lighting Professionals
Learn what a photometric study is, how it works, what data it produces, and why it's required for parking lots, sports fields, and code compliance.
8 min read
Candela, Lumens, and Lux: Understanding the Core Photometric Triangle
Master candela, lumens, and lux relationships. A technical guide to luminous flux, intensity, and illuminance metrics for precise lighting design
20 min read
Beam Angle vs. Field Angle: Specifying Optics for Spotlights
Beam angle, field angle, and optics in spotlights dictate intensity. Specifying accurate narrow distributions ensures compliance in sports and theater lighting
16 min read
Light Loss Factors (LLF): Calculating LDD and LLD for Photometrics
Properly calculate total light loss factor (LLF). Detailed methodology for combining dirt depreciation (LDD) and lumen depreciation (LLD) in lighting software
24 min read
How to Read Zonal Lumen Summaries for Commercial LED Fixtures
Decipher zonal lumen summaries on spec sheets. Understand how lumen output is distributed across various angles to optimize room cavity illuminance targets
15 min read
The Lumen Method (Zonal Cavity Method) for Interior Lighting
Master the lumen method for interior lighting design. A step-by-step technical guide to calculating average illuminance with room cavity ratios and tables.
17 min read
Solid Angles and Steradians: Advanced Photometric Geometry
An advanced breakdown of solid angles and steradians. Learn the fundamental geometry that links luminous flux to luminous intensity for exterior applications
23 min read
Lambert's Cosine Law: Calculating Illuminance on Tilted Surfaces
A complete engineering guide to Lambert's cosine law. Calculate horizontal and vertical illuminance accurately on angled surfaces and architectural facades
18 min read
Reading Luminous Intensity Distribution Curves in Photometry
Learn to read luminous intensity distribution curves. Interpret polar graphs to predict beam spread, max candela angles, and fixture performance accurately.
17 min read
Analyzing TM-30 Color Vector Graphics for Photometric Accuracy
Interpret TM-30 color vector graphics to evaluate LED color shift. Learn how hue bin distortions impact visual clarity in retail and broadcasting environments
19 min read
Photopic, Scotopic, and Mesopic Vision: Impact on Lighting Design
Master mesopic vision, scotopic, and photopic biology to optimize exterior lighting design, maximize perceived brightness, and comply with IES standards
17 min read
Point-by-Point Lighting Calculations: A Technical Designer's Guide
Explore the point-by-point calculation method for exterior lighting. Understand the math behind photometric analysis for parking lots and open site areas
14 min read
The Inverse Square Law in Lighting Design: Formulas and Applications
Master the inverse square law for lighting calculations. Learn how distance impacts illuminance and how to apply the formula in practical photometric design
17 min read