As well as the Transmitter Brown produced the Stereo Photoduplicon (BP 21406/1894), he also wrote a book on the subject and published stereoscopic images. The Transmitter received good reviews but could not have sold well. An improved model had a thumbscrew to alter the angle between the two mirrors for use when photographing subjects at different distances. The connecting bracket was also modified by adding several holes, to which the mirrors attach, allowing the lens to mirror distance to be altered. Around 1905 a version was introduced that attached to the front of the lens rather than the camera baseboard. Brown offered to replace the mirrors if they become damaged but to do so the serial number of the Transmitter was needed; presumably there were several changes made to the instrument. The price was 7/6.

A similar arrangement of mirrors was proposed by Gill and Newton in 1857 (BP 2903/1857).

A simple device to fit on to a tripod head giving 3 ½" separation.

Early models were supplied without a fixing to the camera lens, the rear of the Stereax had screw holes and depressions to which a Kodak Lens Attachment (types 320, 370 and 420) could be fixed. Some, possibly later, versions were fixed to the camera via a bracket that fixed to the underside of the Stereax and to the tripod fitting of the camera. The Stereax was distributed by Photax.

The Stereoly attaches to the Leica camera, it first appeared in 1931 for the Leica I series. In 1932 a version suitable for the rangefinder model was produced, this used the same prism unit but had a different connecting arm.

There are minor differences between versions:

• The 1931 model came in two versions, the first had a rigid view-finder mask with a single positioning notch, later a folding finder mask was fitted and there were two positioning notches. With the connecting arm fitted to the camera the prism unit slides on to the arm and a spring engages the positioning notch.
• The 1932 model originally had two positioning notches on the arm to engage the 5 cm Elmar and the 5 cm Hektor. Shortly afterwards a third notch was added for the 5 cm Summar which was introduced in 1933.
• A version for the model IIIb was advertised in the 1939 US catalogue. This would have had a cut out for the IIIb eye-pieces which are closer together.

This example with three notches to control the distance between the prism head and the lens dates to 1933.

The stereo unit for the Contaflex I and II comprises two prisms positioned in front of the lens to provide the stereo separation. The lens transposes the two images, so they can be mounted directly in a slide holder or printed in an enlarger.