What does lumen per square foot per steradian measure?

It quantifies visible light emitted or reflected by a surface per unit area and solid angle, commonly used in U.S. customary luminance measurements.

Why convert lumen/square foot/steradian to apostilb?

Converting allows users to interpret luminance values according to historical photometric standards and facilitates calibration across different measurement systems.

Is apostilb used in modern lighting design?

Apostilb is a historical unit mainly used in older literature and calibration, while modern lighting design typically prefers SI units.

How to Convert from Lumen/square foot/steradian to Apostilb

Convert luminance values efficiently from lumen per square foot per steradian to apostilb using this easy-to-use online unit converter tool.

Lumen/square foot/steradian

Apostilb

Please check your input. It must be a valid numeric value.

Lumen/square foot/steradian to Apostilb Conversion Table

Lumen/square foot/steradian	Apostilb

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Start Value

Enter the starting number (positive decimal or integer ≥ 0). Example: 0.1, 1, 5.

End Value

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Interval

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Lumen/square foot/steradian to Apostilb Conversion Table
Lumen/square foot/steradian	Apostilb

Explore More Luminance Units Converter

What Is This Tool?

This online converter transforms luminance measurements from lumen per square foot per steradian, a unit commonly applied in U.S. customary lighting contexts, into apostilb, a historical non-SI luminance unit. It simplifies interpreting and comparing brightness values across different measurement systems.

How to Use This Tool?

Enter the luminance value in lumen per square foot per steradian.
Select apostilb as the target unit for conversion.
Click the convert button to get the equivalent luminance in apostilb.
Refer to examples for additional guidance on using values.

Key Features

Converts luminance from lumen/square foot/steradian to apostilb accurately.
Browser-based tool requiring no installation.
Supports use cases in architectural and lighting design fields.
Facilitates calibration and reporting in both customary and historical units.
Provides example conversions to clarify usage.

Examples

1 lumen/square foot/steradian equals 33.815821889 apostilb.
2 lumen/square foot/steradian equals 67.631643778 apostilb.

Common Use Cases

Evaluating brightness of signs, billboards, and outdoor displays in feet-based units.
Assessing glare and visual comfort in architectural lighting projects.
Calibrating luminance meters that output in U.S. customary units.
Reporting screen brightness following older cinematography standards.
Interpreting historical photometric data during imaging equipment calibration.

Tips & Best Practices

Ensure correct unit selection to avoid conversion errors.
Use the tool to facilitate comparison between customary and historical units.
Double-check results when integrating with modern SI-based measurement systems.
Consider spatial unit differences (square foot vs. square metre) during precise calculations.

Limitations

Apostilb is a historical, non-SI unit and may not align seamlessly with modern SI standards.
Conversions require careful handling of differing spatial measurement bases.
May not be suitable for highly precise luminance assessments where SI units dominate.

Frequently Asked Questions

What does lumen per square foot per steradian measure?: It quantifies visible light emitted or reflected by a surface per unit area and solid angle, commonly used in U.S. customary luminance measurements.
Why convert lumen/square foot/steradian to apostilb?: Converting allows users to interpret luminance values according to historical photometric standards and facilitates calibration across different measurement systems.
Is apostilb used in modern lighting design?: Apostilb is a historical unit mainly used in older literature and calibration, while modern lighting design typically prefers SI units.

Key Terminology

Lumen/square foot/steradian: A non-SI luminance unit expressing luminous flux per unit area (square foot) and per unit solid angle (steradian), equivalent to candelas per square foot.
Apostilb: A non-SI, historical luminance unit equal to 1 divided by π candela per square metre, used in older photometric contexts.
Luminance: The measure of luminous intensity emitted or reflected from a surface per unit projected area and per unit solid angle.

Quick Knowledge Check

What does the unit lumen/square foot/steradian represent?

Luminous flux per unit solid angle only

Luminous flux per unit area per unit solid angle

Luminous intensity per steradian only

Which unit is a historical measure of luminance equal to 1/π candela per square metre?

Apostilb

Lumen/square foot/steradian

Candela

What is a primary use case for converting lumen/square foot/steradian to apostilb?

To interpret older photometric and cinematography standards

To measure temperature differences

To calculate electrical power consumption

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