Flash Guide Number Distance Calculator: GN 58 m, f/1.4, ISO 100

Specific conversion page with reference context, calculator, and nearby values.

Author

Dr. Mateo Silva Herrera

Photography editorial contributor

Colombian urban planner with a PhD from UCL, designing resilient infrastructure for flood-prone cities

Reviewed by

Prof. Ingrid Johansson

Photography content reviewer

Norwegian political scientist at the University of Oslo, studying democratic resilience in Nordic welfare states

Last updatedFebruary 22, 2026

PublishedFebruary 22, 2026

GN 58 m, f/1.4, ISO 100 converts to

41.43 m flash distance

Use this as a quick reference for Flash Guide Number Distance Calculator.

Value Details

Input: GN 58 m, f/1.4, ISO 100

Output: 41.43 m flash distance

Browse all reference values for Flash Guide Number Distance Calculator

aperture: 1.4 | iso: 100 | distanceFt: 135.92

Flash Guide Number Distance Calculator

Estimate flash-to-subject distance for manual flash exposure using guide number, aperture, and ISO.

Estimated Flash Distance

Nearby Reference Values

Flash Guide Number Distance Calculator values near GN 58 m, f/1.4, ISO 100
Flash ScenarioDistance (m)Distance (ft)
GN 43 m, f/11, ISO 2005.53 m flash distance18.14
GN 43 m, f/11, ISO 4007.82 m flash distance25.65
GN 43 m, f/16, ISO 1002.69 m flash distance8.82
GN 43 m, f/16, ISO 2003.8 m flash distance12.47
GN 43 m, f/16, ISO 4005.38 m flash distance17.63
GN 58 m, f/1.4, ISO 10041.43 m flash distance135.92
GN 58 m, f/1.4, ISO 20058.59 m flash distance192.22
GN 58 m, f/1.4, ISO 40082.86 m flash distance271.84
GN 58 m, f/2, ISO 10029 m flash distance95.14
GN 58 m, f/2, ISO 20041.01 m flash distance134.55
GN 58 m, f/2, ISO 40058 m flash distance190.29

Frequently Asked Questions

Common questions about Flash Guide Number Distance Calculator, formulas, and expected usage.

How do you calculate flash distance from guide number?

At ISO 100, divide guide number by aperture. For other ISO settings, multiply guide number by the square root of ISO/100 before dividing by aperture.

What does a flash guide number mean?

Guide number indicates flash power for manual exposure planning. A higher guide number generally means the flash can illuminate a subject farther away at the same aperture and ISO.

Why does ISO change effective guide number?

Increasing ISO makes the sensor more sensitive, so the same flash output can expose subjects at a greater distance. The relationship scales with the square root of ISO.

Does this replace test shots and light metering?

No. It is a fast starting estimate for manual flash setup. Modifiers, bounce, zoom head settings, and real scene conditions can change the final exposure.

Methodology and Review

This page is generated from the same conversion definition used by the main calculator page, which keeps the calculator, reference table rows, and FAQ schema aligned.

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Use this page as a fast lookup reference, then confirm final project values using applicable standards and manufacturer documentation.