I have had this lens for quite some time; it came to me on a 4X5 Revolving Back Auto Graflex. It's full markings are:

Mono-Werke, Magdeburg. Heliostigmat f7.7 190mm

The lens is mounted on a non-original board and I do not think it is original to the camera, although it is probably contemporaneous. It is in a brass barrel mount. I do not see a serial number.

I can't say that I have ever heard of "Mono-Werke". If anyone can tell me something about the company, and the lens, I would like to learn more.

Thanks

John

Its a Voigtländer A.G., Wien, Austria, later Braunschweig, (Brunswick), Germany lens. Very little on the Heliostigmat in A Lens Collectors Vade Mecum. Likely a portrait or projection lens as this is the usage for the ones listed.
Happy hunting.

Thanks for the reply. Something about the lens made me think that it might be an early Voigtlander, but there was nothing I could pin down, and the name in the markings made no sense. In any event it looks good on the camera. I'll consider it to be a portrait lens as it is on a camera and not a projector.

John