Originally Posted by Jerevan
Does the Rolleiflex 621 need two plugs for the holes in the back? One at B1 - 6x6 and another one at the bottom position B2 - 6x9?
Or is it only one that one moves around?
The early Rolleiflex Standard cameras had the two red windows, one for 117-film (B1) and one for 120-film (B2), and both had plugs that today are missing on many of these cameras.
Later cameras had the red window for 120-film only and with a sliding cover.
You only use the red window after loading the film to wind to the first frame, and then you set the mechanical counter. From there on the red window(s) should be covered to avoid light leaks.