The camera is poorly made probably by a local carpenter rather than someone experienced in making cameras, very wide pieces of wood have been used without consideration of shrinkage. It is made of unpolished mahogany.

The lens is unusual in being a normal Petzval design with the addition of a third lens placed between the other two. The extra lens is a cemented achromat and smaller in diameter than the front element. The third lens and the front element are both mounted in a tube which slides relative to the rear lens group.

With the third lens removed and the tube retracted the back focus of the lens is 6" and would cover a cabinet size image. With the third lens in place and the tube extended the focal length is reduced and gives a smaller image with a back focus of 4 ½".

The third lens screws into a raised flange at the end of the sliding tube, the outside of the flange also has a male thread this was probably to fit a retaining ring for washer stops or possibly to attach an alternative lens.

Gasc & Charconnet were founded in 1860,¹ the serial numbers written on the edge of the front and rear groups indicate an early date of manufacture. A similar lens was produced by Derogy in 1858 but was not particularly successful.