Is the leica super apo summicron sl 21mm f 2 asph worth buying used?

Here is what the site says about that.

From Leica Super-APO-Summicron-SL 21mm f/2 ASPH: Leica Super-APO-Summicron-SL 21mm f/2 ASPH: A prime lens by Leica for Full frame cameras, 21mm f/2. Specs - Maker: Leica - Focal length: 21mm (prime) - Maximum aperture: f/2 - Made for: Full frame sensors - Mounts: L-Mount - Stabilised: no - Autofocus: yes What it frames like - On full frame (L-Mount): as marked, 21mm. - On APS-C (L-Mount): like 32mm on full frame; f/2 gives about the depth of field of f/3 there. ...

From Buying used: Buying used: Cameras and lenses are built to last, and many photographers upgrade often. That makes the used market one of the best ways to afford good gear. A body that's one or two generations old is often most of the camera for a fraction of the price.

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