Barre des Écrins (4.102 m) is in the middle left of the image. Taken from Pic de Finestrelles (2.820 m) at 440 Km, before sunrise.
Over at aptly named Beyondhorizons.eu is the current long distance photography record held by Marc Bret. It is a picture taken of a peak in the Alps named Barre de Écrins all the way from the top of Pic de Finestrelles in the Pyrenees, a distance of 440km.
Why is this so special?
If we put in the numbers into an earth curve calculator such as this one here the results show that even from such a high attitude as 2820 meters above sea level, an object 440 kilometers away would be 4919 meters below the horizon.
While Barre des Écrins is 4102 meters high, it still needs to be more than 817 meters higher to even peek up above the horizon! Yes, the very tip of it should be 817 meters below the horizon, in other words, taking a picture of it should be completely impossible on the globe earth.
Yet, there it is in all it’s glory, from top to bottom. It is not hidden behind the curvature because there is no curvature.