The interface of the ALPA camera system is square. Therefore all the backs can get attached in portrait or landscape position. This works with the ALPA/Linhof backs (6x7 and 6x9) which are directly adapted as well as with the Mamiya RB and Horseman/ArcaSwiss via the respective ALPA adapter and all the ALPA digital back adapters (Hasselblad V, H1/H2, Mamiaya 645 AFD/AFD II and Contax 645). The front element of the ALPA viewfinder is revolveable according to the back position.