This is a lens of my own design executed by Jaromir Holubec, the owner of optical workshop ATC in Prerov. The lens is based on short flint glass S-NBM51 paired with S-BSM9. It resembles the first Zeiss apochromats which were based on short flints as well.

More details about the oil doublet and my motivations why I built it can be found in this first night report. Here are some additional plots that characterise the performance of the lens: ray trace, spot diagrams, and strehl as a function of light wavelength.