Calculate Lens Magnification / Reproduction Ratio

This calculator will return the magnification and reproduction ratio for a given lens focused at a given point using optionally an extension tube.

Enter the focal length of the lens in millimeters, the extension tube length in millimeters (if applicable), and the focus distance (from sensor plane) in meters/yards/feet/inches/cm/mm.

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Focal length of lens (mm)
Extension tube length (mm)
Focus distance
Focus distance units
Note: some lenses change focal length as they are focused. This is known as focus breathing and will affect the magnification values.

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