This is a very interesting early petzval lens with an early form of iris diaphragm. The lens is in the typical petzval lens arraignment with two air spaced rear elements with a separator between them and two cemented front elements. The focal length is approx 7" and when I put it on a camera it throws a very nice image which looks like it should cover a 4x5 plate. The lens body has no identification on it but when comparring the construction features of the lens it appears to match French lenses such as Derogy. The glass is clean with some internal dust. The diaphragm works fine. The rack and pinion focus works fine. The total length of the lens is 3 3/4" from end to end. The width of the lens body is approx 2.22". It is hard to find a real camera lens in a petzval formula for a smaller format camera. Check out my other auctions for many more early brass large format lenses. I can combine shipping on multiple purchases. Buyer pays shipping and the shipping quote includes insurance.