The Hartmann is the Barton Perreira aviator, and the decision to make it in ultra-thin zyl rather than metal is the decision that defines it. At 58mm it is generous — the large teardrop shape requires a certain confidence to carry — but the thin acetate keeps the visual weight in proportion to the size, a balance the brand achieves through material choice rather than any reduction in scale. The Night Fever gradient lenses are the frame's most distinguishing element: a jewel-tone movement from deep blue at the upper edge through a mid-point transition to warm amber at the base, a colour range that shifts in character depending on which part of the lens catches the light. In Black, the acetate front is resolved and uncomplicated — it exists to carry the lenses without competing with them. Handmade in Japan.