About this tool

Make the direction of light falloff clear.

Falloffnote is a free browser-local tool for comparing two source-to-subject distances under one explicit ideal point-source model. Its purpose is to show the relative illuminance fraction, its reciprocal source-output multiplier and the signs of the corresponding stop changes. It keeps exact arithmetic and approximate logarithms visibly separate.

One task, with context

The old and new distances use a single shared unit. Changing that unit label does not convert either number; the user must enter both in the same unit. Exact fractions are calculated from the entered decimal numbers. Their precision describes the arithmetic, not a measurement of a lamp, subject or scene. Approximate decimal ratios and stops are labeled as such.

The guide names the geometric and photographic references. The original examples explain why doubling distance gives a quarter of the modeled illuminance, and why moving closer reverses the compensation sign. A bounded drawing provides context while clearly saying it is schematic and not to scale.

What this page does not predict

A real extended source, reflector, changed angle or room can behave differently from the declared model. Falloffnote does not measure light, calibrate a source, predict absolute lux or recommend a camera, flash dial or electrical-power setting. It does not claim that its computational input range establishes where a real source is sufficiently point-like.

Local and free

The comparison runs in the open browser page without an input upload or calculation API. This source release has no active external analytics, advertising or consent-platform loader. Ordinary hosting requests still deliver the website; the privacy page explains that boundary. Prepared publisher metadata does not prove advertising approval or earnings.

For a reproducible arithmetic, reference, wording or accessibility issue, use the contact page. It lists the existing shared public forwarding address yardfill.helpful594@aleeas.com, not a new dedicated mailbox. Small non-sensitive examples are enough to investigate a correction without private equipment or account details.