What does watt/sq. cm/steradian (at 555 nm) measure?

It measures radiometric spectral radiance, representing radiant power per unit projected area per unit solid angle at the 555 nm wavelength, aligned with human visual sensitivity.

Why convert to apostilb?

Converting to apostilb allows comparison and compatibility with historical photometric units used in lighting engineering and cinematography.

Can I use this conversion for wavelengths other than 555 nm?

No, the conversion is specific to 555 nm and may not yield accurate results for other wavelengths.

How to Convert from Watt/sq. cm/steradian (at 555 nm) to Apostilb?

Learn how to convert luminance measurements from watt per square centimeter per steradian at 555 nm to the apostilb unit. Understand the key concepts, practical examples, and applications of this conversion.

Watt/sq. cm/steradian (at 555 nm)

Apostilb

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Watt/sq. cm/steradian (at 555 nm) to Apostilb Conversion Table

Watt/sq. cm/steradian (at 555 nm)	Apostilb

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Watt/sq. cm/steradian (at 555 nm) to Apostilb Conversion Table
Watt/sq. cm/steradian (at 555 nm)	Apostilb

Explore More Luminance Units Converter

What Is This Tool?

This converter transforms luminance values measured in watt per square centimeter per steradian at 555 nm into apostilb, a non-SI historical unit of luminance. It assists in relating radiometric spectral radiance at the photopic peak to traditional photometric luminance measurements.

How to Use This Tool?

Enter the luminance value in watt per square centimeter per steradian (at 555 nm)
Choose the target unit, apostilb, for conversion
Click the convert button to obtain the equivalent luminance in apostilb

Key Features

Converts spectral radiance at 555 nm wavelength to apostilb luminance values
Supports unit translation useful for vision research and optical metrology
Provides straightforward numerical conversion with included formula
Ideal for compatibility with historical and legacy photometric data

Examples

0.5 watt/sq. cm/steradian (at 555 nm) converts to 10728538.912009 apostilb
2 watt/sq. cm/steradian (at 555 nm) converts to 42914155.648036 apostilb

Common Use Cases

Characterizing spectral radiance of light sources at the photopic peak for vision studies
Converting radiometric radiance data to photometric units for luminance comparison
Specifying LED or lamp output in photometric testing and optical metrology
Reporting brightness in historical photometric and cinematographic contexts
Calibrating imaging equipment using legacy luminance units

Tips & Best Practices

Ensure input values correspond to measurements at exactly 555 nm wavelength
Use the converter to bridge radiometric and photometric data accurately within the spectral context
Refer to SI units like candela per square metre for modern photometric standards
Apply conversion cautiously when comparing data from different spectral ranges

Limitations

Conversion applies only to measurements at the 555 nm wavelength peak
Apostilb is a historical, non-SI unit with limited use in current standards
High precision depends on the accuracy of spectral sensitivity and measurement conditions
Using this converter outside the specified spectral context may cause inaccuracies

Frequently Asked Questions

What does watt/sq. cm/steradian (at 555 nm) measure?: It measures radiometric spectral radiance, representing radiant power per unit projected area per unit solid angle at the 555 nm wavelength, aligned with human visual sensitivity.
Why convert to apostilb?: Converting to apostilb allows comparison and compatibility with historical photometric units used in lighting engineering and cinematography.
Can I use this conversion for wavelengths other than 555 nm?: No, the conversion is specific to 555 nm and may not yield accurate results for other wavelengths.

Key Terminology

Watt/sq. cm/steradian (at 555 nm): A radiometric spectral radiance measure expressing radiant power per unit projected area per solid angle at the wavelength 555 nm.
Apostilb: A non-SI, historical unit of luminance equal to 1 divided by π candela per square metre, used for measuring luminous intensity from surfaces.
Luminance: The measure of luminous intensity emitted or reflected from a surface per unit projected area in a specific direction.

Quick Knowledge Check

What is the apostilb unit primarily used for?

Measuring electrical current

Describing luminance from surfaces historically

Calculating sound intensity

At which wavelength is watt/sq. cm/steradian measurement referenced?

555 nm

650 nm

450 nm

Why is the 555 nm wavelength important in this conversion?

It matches the peak of photopic human visual sensitivity

It corresponds to ultraviolet light

It is unrelated to any visual sensitivity feature

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