NPF Rule (Sharp Stars) Calculator
Estimate npf rule (sharp stars) calculator using practical photography and optics formulas for planning shoots and gear choices.
500 Rule Exposure
20.83 s
NPF Approx Exposure
9.46 s
Image Scale
36.96 arcsec/pixel
Tracking Tolerance
25.87 arcsec
SNR Gain (16 Frames)
4.00 x