Is the zeiss milvus 18mm f 2 8 worth buying used?

Here is what the site says about that.

From Zeiss Milvus 18mm f/2.8: Zeiss Milvus 18mm f/2.8: A prime lens by Zeiss for Full frame cameras, 18mm f/2.8. Specs - Maker: Zeiss - Focal length: 18mm (prime) - Maximum aperture: f/2.8 - Made for: Full frame sensors - Mounts: Canon EF, Nikon F - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Canon EF, Nikon F): as marked, 18mm. - On APS-C (Nikon F): like 27mm on full frame; f/2.8 ...

From Zeiss Milvus 21mm f/2.8: Zeiss Milvus 21mm f/2.8: A prime lens by Zeiss for Full frame cameras, 21mm f/2.8.

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