In the 1996 book, Ansel Adams: A Biography, there is a references to Best Studios in Yosemite selling a series of 1922 landscapes shot by Ansel with a Zeiss Miroflex camera.
The Miroflex was a folding SLR for plates, about the size of a contemporary press camera. This was originally a post WWI Contessa-Nettel camera from 1919. It was carried over into Zeiss Ikon in 1926, and was produced until 1936. The camera is based on the Nettel, a strut folding press camera with a focal plane shutter.
The bellows are open at the top, capped with a ground glass and a folding viewing hood. Inside the bellows is the reflex mirror, which swings up out of the way and caps the top of the bellows during exposure. The mirror can be left up, and the viewing hood folded down, to create a press camera.
The camera was popular in two available sizes: Miroflex A (6.5 x 9 cm image) and Miroflex B (9 x 12 cm image).