Will your target fit the frame?
Pick a target preset or enter dimensions, then set your gear to see how well it fills your sensor.
Inputs
1 = none, <1 = reducer, >1 = Barlow
Results
Adjust the inputs to see results.
Small-angle FOV (Huygens formula) compared to target apparent size: fill% = min(FOV/target) × 100.
All formulas verified by automated tests.