Did the cold move your focus?
Enter your scope type, aperture, and temperature change to estimate focus shift in microns.
Inputs
Negative = cooled since last focus
Results
Adjust the inputs to see results.
Empirical coefficients by scope type: refractor ~0.08, reflector ~0.02, cat ~0.01 µm per °C per 100 mm aperture.
All formulas verified by automated tests.