Collimation Calculator

Calculate secondary mirror offset and collimation tolerance for Newtonian reflectors.

Focal Ratio (f/X)

Primary Diameter (in)

Secondary Minor Axis (in)

Tab to move between fields

Secondary Offset

0.44 mm

Alignment Tolerance

0.079 mm

Difficulty (1=Easy, 3=Critical)2

How to Use This Calculator

Enter Focal Ratio (f/X), Primary Diameter (in), and Secondary Minor Axis (in).
Review Secondary Offset (mm) and Alignment Tolerance (mm).
Use Difficulty (1=Easy, 3=Critical) to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Secondary Minor Axis (in)

Focal Ratio (f/X): f/ratio of the primary mirror (lower = faster, more collimation-sensitive)
Primary Diameter (in): Diameter of the primary mirror in inches
Secondary Minor Axis (in): Minor axis dimension of the diagonal secondary mirror in inches

Identify Input Parameters
Focal Ratio (f/X) = 6, Primary Diameter (in) = 8, Secondary Minor Axis (in) = 1.83 = 3 input(s) provided
Calculate Secondary Offset
Secondary Offset
0.44 = 0.44
Calculate Difficulty
2 = 2

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