Yes, there is a 120 film camera that shoots 6×3. The camera in question is the Horseman 6×9 Roll Film Back for 6×12 Cameras, which is designed to fit on 6×12 cameras such as the Horseman VH-R and the Horseman VH.
The Horseman 6×9 Roll Film Back has a built-in film mask that allows for shooting in 6×3 format. This format is achieved by exposing half of the 6×9 frame with each shot, resulting in two images on a single 6×9 negative. The resulting images have a 3:1 aspect ratio and measure approximately 56mm x 168mm.
The Horseman 6×9 Roll Film Back is a versatile accessory that allows photographers to shoot in multiple formats without the need for multiple cameras. In addition to the 6×3 format, it also supports standard 6×9, 6×8, and 6×7 formats. The back is easy to install and remove, making it a convenient option for photographers who want to switch between formats quickly.
The Horseman 6×9 Roll Film Back is a reliable and durable accessory that is popular among film photographers. It has been in production for many years and is readily available on the used market. The back is compatible with a wide range of lenses and cameras, making it a versatile option for photographers who shoot with medium format film.