Instruments used by Davidson and Crommelin in Sobral, Brazil 1919.
In 1919 when Eddington, Dyson, Davidson and Crommelin completed their experiment they used the enormous astrographic telescopes, such as the one shown above. They basically photographed the position of certain stars as they appeared normally and compared these positions to where they appeared during the solar eclipse.
Image courtesy of Bruns, 2016
The theory behind this is what is now known as Gravitational Lensing. Essentially, the huge gravitational pull of the sun causes the light to bend, which means the location of the stars as we see them on Earth is different to their actual location. During a solar eclipse the sun is blocked out allowing us to see the real position of these stars and measure exactly how much the sun's gravitational pull causes them to deflect.
We shall be re-creating this experiment using both the historical astrographic telescopes as well as more modern technology (specifically the Tele Vue Refractor Telescope). We shall be determining the angle of deflection and comparing to the original value proposed by Newton and the alternative value proposed by Einstein.