Up for sale is an absolutely stunning and extremely rare lens - Dallmeyer Anastigmat 2". I wasn't able to confirm 100% - what this lens is, but doing some researches and test, I've got some thoughts about it, what I'll be happy to share with you here.

First of all it's a pretty small lens - miniature size. The lens has build in curcular aperture with number 9 engraved on it and my test confirms that this is about right and with this circle the aperture of the lens is stopped down to f9. Despite being such a tiny size - the lens has enough back focal flange distance - to be used with M42 mount and it's fully covering medium format camera sensor with no vigneting! Please, see the attached test photo, made with this particular lens and Fuji GFX50R camera (not 35mm mode, but full sensor size!).

Trying to find an information about this lens - the first potential clue was obtained from "Vademecum", where it was mentioned miniature dallmeyer super six 2" f1.9 (please, check the attached screenshot). What makes me think that it might be a miniature super six? Well, first of all if you look - how small is f9 aperture circle, compare to the wide open, you can see that it's most likely that tye wide open aperture value is about f2 ish. Also, I've compare the size of the front lens element, with another very interesting miniature lens - Ross Xpress 2" f2.75 and you can see on the picture, attached to this listing, that the front element in this Dallmeyer is that much bigger  to the front element of Ross f2.75, which make very posible for the lens to be, f1.9. Also, if you look at the unscrewed lens elements, you can see that the design of the lens is rather complex and consists of multiple elements in several groups. And the last, but not least, if you will see the attached photo sample from this lens, made with GFX camera - despite that it was made on f9, you can still see that "signature" super six look there.

In other words, it is rather an extremely rare miniature Dallmeyer 2" f1.9 Super Six or a Prototype with similar optical parameters.

Now lets talk about the condition of this lens. The lens is basically in a very good shape, especially referring to its age and rareness. The metal body of the lens has some age marks on it, but nothing serious. The glasses might have some light cleaning marks, but nothing serious. Overall the lens looks absolutely beautiful.

I was planning to remove the metal circular aperture from this lens and install the iris one, but then I realized that considering the rareness of this lens (potentially might be ine of a kind) it might be a good ideal to keep it as authentic as possible, which might be very important for it's future owner.

I'm pretty sure, that it will be no possible to find the same lenses in such a condition now days.