Field Of View

{
  "asOf": "2026-10-11T08:40:15.037Z",
  "atDistanceM": 10,
  "class": "normal-wide",
  "degraded": false,
  "diagonalDeg": 46.793,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "focalMm": 50,
  "horizontalDeg": 39.598,
  "notChecked": [
    "lens distortion and the real focal length at close focus (breathing)",
    "video crops, stabilisation crops and aspect-ratio changes",
    "…1 more"
  ],
  "reasons": [
    "Angle = 2 x atan(sensor dimension / (2 x focal length)). Diagonal angle is the figure lens makers quote.",
    "Classification by diagonal angle: normal-wide."
  ],
  "sceneHeightM": 4.8,
  "sceneWidthM": 7.2,
  "sensor": "full-frame",
  "sensorMm": {
    "diagonal": 43.267,
    "height": 24,
    "width": 36
  },
  "source": "computed locally",
  "summary": "50 mm on full-frame: 39.6 deg horizontal, 26.99 vertical, 46.79 diagonal (normal-wide); at 10 m it covers 7.2 m x 4.8 m.",
  "verdict": "COMPUTED",
  "verticalDeg": 26.991
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://photo-calc.x402tookit.com/field-of-view?distanceM=10&focalMm=50&sensor=full-frame'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://photo-calc.x402tookit.com/field-of-view?distanceM=10&focalMm=50&sensor=full-frame' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fphoto-calc.x402tookit.com%2Ffield-of-view
const res = await pay("https://photo-calc.x402tookit.com/field-of-view?distanceM=10&focalMm=50&sensor=full-frame");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://photo-calc.x402tookit.com/field-of-view?distanceM=10&focalMm=50&sensor=full-frame")
    print(res.status_code, res.text)