---
title: "Narrowband Filters — Imaging Through Light Pollution"
canonical: https://stackingstarlight.com/advanced/narrowband-filters
description: "Narrowband filters (3–7nm) isolate single emission lines (Hα, OIII, SII), blocking 99%+ of light pollution to image from cities."
---

# Narrowband Filters — Imaging Through Light Pollution

> Narrowband filters (3–7nm) isolate single emission lines (Hα, OIII, SII), blocking 99%+ of light pollution to image from cities.

Narrowband filters pass only a sliver of spectrum (typically 3–7nm) around a single emission line — **Hα** (656nm), **OIII** (501nm), or **SII** (672nm). Because nebulae emit strongly at these lines while light pollution and moonlight are broadband, narrowband filters reject 99%+ of unwanted light, enabling deep emission-nebula imaging from bright cities and even under a full moon. The cost: only emission targets benefit (not galaxies/broadband), and per-channel exposures are long. Narrower filters reject more pollution but cost more and demand precise focus.

---

Source: [https://stackingstarlight.com/advanced/narrowband-filters](https://stackingstarlight.com/advanced/narrowband-filters) · Part of [Stacking Starlight](https://stackingstarlight.com) by Michael Kalika.

LLM resources: [LLM index (llms.txt)](https://stackingstarlight.com/llms.txt) · [Complete LLM text (llms-full.txt)](https://stackingstarlight.com/llms-full.txt) · [Markdown homepage (index.md)](https://stackingstarlight.com/index.md)