---
title: "Calibration Frames — Bias, Darks, Flats"
canonical: https://stackingstarlight.com/calibration
description: "Calibration frames — bias, darks, and flats — remove fixed, repeatable defects so stacking only averages real signal and random noise."
---

# Calibration Frames — Bias, Darks, Flats

> Calibration frames — bias, darks, and flats — remove fixed, repeatable defects so stacking only averages real signal and random noise.

Calibration removes everything in your frames that *isn't* sky signal. **Bias frames** (zero-length, capped) capture the electronic baseline — read-noise pattern, ADC pedestal, column banding. **Dark frames** (same exposure and temperature as your lights, lens capped) capture thermal current, hot pixels, and amp glow. **Flat frames** (evenly illuminated, ~50% histogram) map vignetting, dust shadows, and per-pixel sensitivity. The calibration math: `calibrated = (light − master_dark) / normalized_flat`. Bias/darks are *subtracted*; flats are *divided*. Stack many of each so calibration adds no noise of its own.

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Source: [https://stackingstarlight.com/calibration](https://stackingstarlight.com/calibration) · 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)