Uploaded October 2017 | Updated September 2026, 1 week ago
I have bought this used mechanical theodolite for about 250€. It is not the most accurate model, but accurate enough to get an idea of the drop of the horizon.
Theodolite model: Geo-Fennel FET 500
Link to manual for the theodolite: geo-fennel.de/uploads/tx_produkte/FET_500.pdf
Link to discussion on how to calculate the drop of the horizon using the globe Earth model, physics.stackexchange.com/questions/139348/why-does-the-sea-horizon-line-always-seems-to-be-at-the-same-height-as-ones-eye
I have bought this used mechanical theodolite for about 250€. It is not the most accurate model, but accurate enough to get an idea of the drop of the horizon.
Theodolite model: Geo-Fennel FET 500
Link to manual for the theodolite: geo-fennel.de/uploads/tx_produkte/FET_500.pdf
Link to discussion on how to calculate the drop of the horizon using the globe Earth model, physics.stackexchange.com/questions/139348/why-does-the-sea-horizon-line-always-seems-to-be-at-the-same-height-as-ones-eye
