Star Motion Shutter Speed Limit

Calculates max exposure time based on pixel pitch, effective focal length, declination, and your trailing tolerance.

Entry Fields

Sensor Format

Megapixels (MP)

Focal Length (mm)

Trailing Tolerance (pixels) 1 pixel = strict pinpoint stars. Typical is 4–7 pixels.

Target Declination (degrees) 0° is fastest sky motion. 30° works well for Milky Way core.

Max shutter time (pinpoint threshold):

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Enter values and hit Calculate.

Formula used: Tmax = (Cgeom · P · tolerance) / (Feffective · cos(δ))