What does lumen/sq. meter/steradian measure?

It measures luminance, representing luminous intensity emitted, reflected, or transmitted from a surface per unit area per unit solid angle, expressed equivalently as candela per square meter.

Why convert from lumen/sq. meter/steradian to apostilb?

Conversion is useful to interpret luminance values in historical or non-SI units common in older photometric data and cinematography, enabling comparison and calibration.

Is the apostilb still widely used today?

No, the apostilb is a largely historical unit, mostly replaced by SI units but still relevant for certain legacy data and research.

How to Convert from Lumen/sq. meter/steradian to Apostilb?

Learn how to convert luminance measurements from lumen per square meter per steradian (lm·m⁻²·sr⁻¹) to the historical unit apostilb (asb) with this easy-to-use online converter tool.

Lumen/sq. meter/steradian

Apostilb

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Lumen/sq. meter/steradian to Apostilb Conversion Table

Lumen/sq. meter/steradian	Apostilb

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Start Value

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

End Value

Enter the ending number (positive decimal or integer > Start Value). Example: 10, 50, 100.

Interval

Enter the step size (positive decimal > 0 and < End Value – Start Value). Example: 1.0, 2.5.

Lumen/sq. meter/steradian to Apostilb Conversion Table
Lumen/sq. meter/steradian	Apostilb

Explore More Luminance Units Converter

What Is This Tool?

This converter transforms luminance values measured in lumen per square meter per steradian into apostilbs. It helps users relate modern SI units to a historical photometric unit for applications in display brightness, lighting design, and optical measurements.

How to Use This Tool?

Enter the luminance value in lumen per square meter per steradian you want to convert
Select lumen/sq. meter/steradian as the source unit and apostilb as the target unit
Click the convert button to get the equivalent luminance value in apostilbs
Review converted results to interpret brightness data in legacy or non-SI units

Key Features

Converts luminance from lumen/sq. meter/steradian to apostilb
Uses a precise conversion factor based on the relationship between units
Supports understanding of luminance in both modern and historical contexts
Browser-based and easy to use without requiring special software

Examples

1 lumen/sq. meter/steradian = 3.1416 apostilb
5 lumen/sq. meter/steradian = 15.7079 apostilb

Common Use Cases

Specifying and comparing display brightness for devices like monitors and TVs
Designing lighting and signage with appropriate brightness and glare control
Performing photometric measurements for camera exposure and glare evaluation
Analyzing historical photometric data and calibrating imaging equipment in older systems

Tips & Best Practices

Verify the unit definitions before conversion to avoid errors in interpretation
Use this tool to bridge between modern SI luminance measurements and historical data
Be aware of the historical nature of the apostilb when applying results
Cross-check conversions when working with legacy photometric specifications

Limitations

Apostilb is a non-SI, historical unit and less common in current standards
Conversion accuracy depends on the handling of π’s value in calculations
Differences in unit conventions can cause confusion between legacy and modern data

Frequently Asked Questions

What does lumen/sq. meter/steradian measure?: It measures luminance, representing luminous intensity emitted, reflected, or transmitted from a surface per unit area per unit solid angle, expressed equivalently as candela per square meter.
Why convert from lumen/sq. meter/steradian to apostilb?: Conversion is useful to interpret luminance values in historical or non-SI units common in older photometric data and cinematography, enabling comparison and calibration.
Is the apostilb still widely used today?: No, the apostilb is a largely historical unit, mostly replaced by SI units but still relevant for certain legacy data and research.

Key Terminology

Lumen/sq. meter/steradian: A unit of luminance quantifying luminous intensity per unit area per solid angle, equivalent to candela per square meter.
Apostilb: A non-SI, historical unit of luminance equal to 1 divided by π candela per square meter used in older photometric contexts.
Luminance: The measure of luminous intensity emitted or reflected from a surface per unit projected area in a given direction.

Quick Knowledge Check

What is the apostilb?

A unit of luminous flux

A non-SI historical luminance unit equal to 1/π candela per square meter

A measurement of light wavelength

Which unit is equivalent to lumen/sq. meter/steradian?

Candela per square meter

Lux

Apostilb

Why is conversion between lumen/sq. meter/steradian and apostilb important?

To convert brightness into lux

To relate modern SI luminance units to historical photometric units

To measure color temperature

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