Contaprox Type I, model 5522/13. Manufactured by Carl Zeiss Jena. A close-up accessory for the Contax IIa / IIIa, produced after the war. The taking lens is a Carl Zeiss Jena Tessar 50mm f3.5 with T coating.
It consists of a focusing head, extension ring, and focusing screen. It allows for even closer focusing than the Contameter.
When shooting, mount the accessory on a tripod using the tripod socket below the lens, adjust the subject distance precisely with the focusing screen, then replace the focusing screen section with the camera body to make the exposure.
A finely crafted and highly precise accessory.

Originally sold by our shop and carefully used by the previous owner, this item remains in excellent condition, unchanged from the previous sale. Minor marks are visible on the tripod mount, likely from attachment, and slight rubbing can be seen on the black paint areas, but overall it shows very little signs of use and retains a clean appearance.
In 2024, the lens was professionally serviced, including cleaning, aperture adjustment, and focus inspection. The front element of the Tessar shows some light wipe marks, and the coating around the edge of the rear element shows slight deterioration, though these have little to no effect on actual photography.
Comes with the original English instruction manual and case.
A fine piece for your collection.