Petzval lenses consist of two groups of elements, a cemented doublet at the front and a doublet or two singlets at the rear. Projection lenses, have no focusing mechanism or iris diaphragm, and they generally come apart, so it is fairly easy to try combining different the front element groups of one lens with the rear group of another. This does invariably compromise the lens performance is one manner or another, and usually the compromises result in images that are unpleasing: with severe haloing, loss of sharpness, contrast, poor edge performance, etc. But sometimes the combination results in aberrations that are aesthetically pleasing. This is, I believe one of those. The front elements come from a very common Russian projection lens, the KO-12oM, a 120mm f1.8 design for 35mm film projection. I combined that here with the rear group from an Angenieux Type 65 120mm projection lens, also for 35mm. The result was a lens with very good resolution in the center, but with a very curved field. I find the bokeh also very much to my taste.
