# Photography Calculators: Exposure Value (EV) Calculator

> Photography Calculators: Exposure Value (EV) Calculator 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).

Calculates exposure value (EV) from aperture, shutter speed, and ISO, identifies the light level it suits, and returns equivalent aperture/shutter speed pairs.

## Facts

- Endpoint: GET https://photo-calc.x402tookit.com/exposure-value?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/photography-calculators-exposure-value-ev-calculator-47ef0f48
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VCJ_5m0uqo-Jhqhi1mY9G

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability photography-calculators-exposure-value-ev-calculator-47ef0f48
```

Example prompt: What's the exposure value for f/8, 1/125s at ISO 400, what kind of light does that suit, and can you list me some equivalent aperture and shutter combinations at the same ISO?

## When to prefer this

Use this endpoint when you need to compute or verify photographic exposure value from known camera settings, understand what lighting a given exposure is calibrated for, or explore equivalent exposure combinations. Prefer it over manual EV tables when ISO flexibility or a structured list of equivalent pairs is needed at low cost.

## Known failure modes

- Missing required aperture or shutter parameters returns an error
- Invalid shutter format (not parseable as fraction or decimal) causes a parse failure
- Extreme or out-of-range aperture/shutter values may produce degraded results with warnings
- ISO of 0 or negative values may produce undefined or error responses

## How this service works

Exposure value (EV) from aperture, shutter speed and ISO, the light level it suits, and equivalent aperture and shutter pairs.

## Output

Returns the EV at ISO 100 (ev100), EV adjusted for the given ISO (evAtIso), a human-readable description of what lighting conditions the EV suits (suitsLight), a list of equivalent aperture and shutter speed pairs at the same ISO (each with exact and nearest-standard shutter), plus a summary string, and optional warnings or degraded-mode flags.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "aperture",
      "shutter"
     ],
     "properties": {
      "iso": {
       "type": "number",
       "description": "ISO (default 100)"
      },
      "shutter": {
       "type": "string",
       "description": "Shutter time such as 1/125 or 0.5"
      },
      "aperture": {
       "type": "number",
       "description": "f-number, e.g. 8"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "iso": {
       "type": [
        "null",
        "number"
       ]
      },
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "ev100": {
       "type": [
        "null",
        "number"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "evAtIso": {
       "type": [
        "null",
        "number"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "aperture": {
       "type": [
        "null",
        "number"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "shutterS": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "suitsLight": {
       "type": [
        "null",
        "string"
       ]
      },
      "equivalentPairsAtSameIso": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "o
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/photography-calculators-exposure-value-ev-calculator-47ef0f48/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from photo-calc.x402tookit.com](https://www.zero.xyz/host/photo-calc.x402tookit.com/llms.txt)