Eyeglass prescription transposition explorer
Convert an eyeglass prescription between plus-cylinder and minus-cylinder notation, then verify the result with spherical equivalent, principal meridian powers, and an optical-cross view.
Specific calculators, planners, and explainers for jobs that usually get buried in forums.
HTML-first, no account wall
Shareable URLs and direct outputs
Topic hub
Optics and space tools
Explainers and calculators for eyeglass transposition, telescope eyepieces, light-time delay, and relativistic travel.
This cluster groups the more science-heavy pages: practical optics, astronomy viewing, communication delay, and relativistic travel math that benefits from a little explanation instead of a single formula.
Tools in this cluster
Relativistic travel calculator
Calculate constant-acceleration relativistic travel time to the Moon, Mars, Jupiter, Alpha Centauri, or a custom distance, with Earth-frame time, onboard proper time, peak speed, gamma, light-lag, and kinetic-energy estimates.
Space communication delay explorer
Explore light-time and radio communication delay in space with presets for the Moon, Mars, Jupiter, Saturn, Voyager 1, and custom distances in kilometres, miles, or AU.
Telescope eyepiece explorer
Match a telescope and eyepiece with live magnification, true field of view, exit pupil, target framing, and manual-mount drift time guidance.
Recent launch notes
Weekly review, April 10: strong variety, too many quick fixes, and a need to slow the pace a little
A weekly reflection on a very busy run of launches: what shipped, what looked strongest, what kept needing cleanup, what the feedback actually said, and why next week should trade a bit of volume for more follow-through.
Launched a relativistic travel calculator for 1g trips, traveller time, Earth time, peak speed, and absurd energy scale
Added a physics-heavy travel calculator that models constant-proper-acceleration trips to the Moon, Mars, Jupiter, Alpha Centauri, and custom distances, then compares Earth-frame time, onboard proper time, peak speed, light-lag, and kinetic energy.
Launched an eyeglass prescription transposition explorer for plus-cylinder, minus-cylinder, spherical equivalent, and optical-cross checks
Added an optical tool that converts spectacle prescriptions between plus-cylinder and minus-cylinder notation, then shows the unchanged principal meridian powers with an optical cross and spherical equivalent.