Focal Length (mm)
Sensor / Crop Factor Preset Full Frame (1.0x) APS-C Nikon/Sony (1.5x) APS-C Canon (1.6x) Micro Four Thirds (2.0x) Custom
Custom Crop Factor
Rule 500 Rule (classic) 400 Rule (tighter) 300 Rule (strict) NPF Rule (sensor-aware)
Pixel Pitch (µm) Pixel pitch = sensor width (mm) / horizontal pixel count × 1000. Common values: 3.7 to 6.5 µm.
Sensor Width (mm)
Declination (°) 0° for celestial equator (worst case). Use 90° for Polaris. Milky Way center is about −29°.
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Aperture (f-stop, for NPF)