199/4.5 Dagor-S design type?

[Jim Galli]

Ross Wide Angle Xpres used so successfully as an aerial lens is I believe, an f4 plasmat.

[Arne Croell]

I remember someone on eBay a few years back selling both an SL and a SV Dagor. I remember one of them being 50mm f.l., but I don't remember which one.

I do have a 199mm f4.5 Dagor-S, and I can confirm that it is neither a Dagor, plasmat, or Artar/Gotar/Celor design. I have never mounted it nor checked the coverage in any way, so I have no clue what it can do. Both front and rear cells have deep curves, all convex w.r.t the aperture. I checked the reflections, and there are 4 bright reflections/cell, plus 1 fainter reflection. The fainter reflection corresponds to a nearly flat lens surface. I can't find my copy of Henney and Dudley, but my guess would be a double Gauss design something like shown below:

John,

why not a Plasmat? The reflections you describe would go with either a Planar or a Plasmat, both are 6/4; except for the outermost reflection, it is sometimes hard to tell from what "depth" a reflection comes.

[John Schneider]

why not a Plasmat? The reflections you describe would go with either a Planar or a Plasmat, both are 6/4; except for the outermost reflection, it is sometimes hard to tell from what "depth" a reflection comes.

I guess I had it in my head that it was a double Gauss, but you could be right as well. The mechanical design is such that you can only pull out the lens elements by unscrewing the trim ring around the front element and going in that way, and I have no strong desire to do that to a lens that doesn't need cleaning. But someday my curiosity may get the better of me...