I received today three Dagors: 12.5cm f/6.8, 180/6.8 and the most exciting one, a Weitwinkel-Dagor 150/9

The other ones aren't really that exciting so I'll concentrate on the Weitwinkel one.

The only other Weitwinkel-Dagor marked lens I've seen is a 210mm f/9 Weitwinkel Dagor. The only mention I've found of this lens is on an eBay auction #110136534579 . It is indeed VERY similar to the one I purchased with the exception of being in a barrel.

I know there is a Zeiss line of Dagors with an aperture of f/9 but this says C.P Goerz Berlin. Could this be a prototype Goerz-designed wide-angle Dagor made just before the merging to Zeiss?

One thing about this lens annoys me a whole lot. It didn't come with a retaining ring. It's the same diameter as a #1 shutter (about 39mm) but with a slightly coarser pitch. A #1 retaining ring turns in about 2 turns before stopping. With the exception of the retaining ring, everything else is just fine. Lens elements are bright and shiny, speeds are accurate within half a stop and the aperture blades are clean.

Considering its apparent rareness, how much would it be worth? I don't have a 8x10 camera and even if I did, I probably wouldn't want to use this one on it. Besides, I'm not really into collectibles. I prefer to actually use my gear.

ANY opinions on this one are greatly appreciated. I tried searching for information but nothing turned up. Some mentions of a Goerz designed wide-angle Dagor but nothing beyond that.

Here's a picture of the lens. The first is just a shot with the other ones in it.