This is the "Steinheil München Macro-Quinon 55mm F1.9," a macro photography lens released in 1963 by Steinheil, a long-established German optical equipment manufacturer. For macro lens enthusiasts, this is a lens you'd want to try alongside the Macro Switar... With an extremely bright aperture of F1.9 for a macro lens, it's a 4-group, 6-element Gauss-type lens. It shares the same configuration as the Auto-Quinon 55mm F1.9 for portraits, but it's designed with aberration correction that takes into account the variation in aberrations with shooting distance, allowing it to achieve the best performance at close range. It has a maximum magnification of 1.4x, and the sophisticated 2-stage helicoid design, with its high precision and meticulous assembly, is truly impressive. It maintains optical performance at a consistent level even when fully extended, without any decentering. It's an Exakta mount, but it has an AF chip-equipped Canon EF mount attached with screws. The EF mount can be removed. When the focus is achieved, it's confirmed with a sound and a red light, so you won't miss the focus. This lens didn't originally come with a hood, but a hood can cut out stray light, which improves the contrast of the photos, so attaching a hood is quite effective. Because it's a rare lens and a bit heavy, I often take other macro lenses with me, so I haven't used it much. Therefore, it's in beautiful condition for an old lens (62 years old), with no scratches, dust, or mold. I would like to ask those who are overly concerned about such things to refrain from purchasing. Macro lenses that exceed 1:1 magnification have been very few in number to this day. A world beyond 1:1 magnification opens up a different realm. If you love macro photography, this is a lens you should definitely try. Thank you for your consideration.