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Photography Calculators – Shutter Speed Rules
x402
Photography Calculators – Shutter Speed Rules is a paid API for AI agents from photo-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Returns minimum handheld shutter speed (reciprocal rule) and maximum star-trail-free exposure times (500 rule and NPF rule) for a given focal length, sensor, and optional parameters.
Price / call$0.02
Success—
StatusUnknown
How this service works
Minimum handheld shutter speed (reciprocal rule) and the longest star-point exposure by the 500 rule and the NPF rule.
Output
A JSON object containing: minimum handheld shutter speed (as a fraction string and seconds), handheld speed with stabilisation, star exposure limits from the 400, 500, and NPF rules (in seconds), equivalent full-frame focal length, crop factor, sensor name, summary verdict text, and any warnings or disclaimers.
Example use cases
Astrophotography star-point exposure planning
“I'm shooting the Milky Way tonight with a 14mm f/2.8 lens on a full-frame camera — pixel pitch is 5.9µm, and the stars I want are near the celestial equator. What's the longest exposure I can use with the NPF rule before stars start to trail?”
Handheld telephoto minimum shutter check
“I'm shooting sports with a 200mm lens on an APS-C camera that has 2 stops of image stabilisation. What's the minimum handheld shutter speed I should use, with and without accounting for the stabilisation?”
Star exposure comparison across rule systems
“For a 24mm lens on a micro-four-thirds sensor at f/1.8, can you give me the star-trail-free exposure times from both the 500 rule and the NPF rule so I can compare them?”
Technical details
Endpoint
GEThttps://photo-calc.x402tookit.com/shutter-rule?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need quick, standards-based shutter speed recommendations for handheld shooting or astrophotography star-point exposures across multiple rules (reciprocal, 500, NPF) in a single call. It is especially valuable when shooting conditions require comparing NPF precision against the simpler 500-rule, or when IS/IBIS stops need factoring in. Use alternatives if you need full manual EV calculation or exposure bracketing.
Side effects
- Missing required focalMm parameter returns a validation error
- Very extreme focal lengths (e.g. <1mm or >10000mm) may produce unreliable results
- NPF rule outputs may be null if aperture or pixelPitchUm are not provided
- Invalid sensor string defaults to full-frame without warning
- Negative or zero stabilisationStops may produce unexpected handheld values
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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