Depending on the model of TLR, the resulting image may have an old-fashioned feel to it, often with vignetting, blurred edges, distortion and dust.
TLR models popular among TtV photographers have a brilliant type ('bubble glass') viewfinder.
While waist-level viewfinders have been common in box cameras since the beginning of the 20th century, large viewfinders of the sort that are suitable for TtV photography became popular in the late 1920s and 1930s with medium format TLR and pseudo TLR cameras such as the Rolleiflex and the Voigtländer Brillant.
Before the advent of digital photography it was necessary to use extension tubes to photograph a close-up object such as a viewfinder, and it was difficult to judge focusing precisely.
The following equipment is required: The contraption may be a simple cardboard tube, or an open ended box that fits around the bottom camera.
The cropping is necessary because in most cases the (normally square) viewfinder image covers only about 25- 50% of the area of the (normally rectangular) digital picture.