Ranft was born in Plainpalais and began studying painting and drawing in Geneva, under the direction of Eugene Etienne Sordet (1836-1915), who taught him the art of landscape painting. He then moved to Paris, where he attended the workshops of Gustave Courbet and Augustin-Alexandre Dumont, a sculptor who taught him engraving. Ranft then created many lithographed plates, including posters and etchings, while continuing with landscape painting.
In Paris he was elected a Full Member of the Société Nationale des Beaux-Arts, in whose Salons he exhibited regularly as well as in the Société des Artistes Indépendants.