Is the pentax smc da 50mm f 1 8 worth buying used?

Here is what the site says about that.

From Pentax smc DA 50mm f/1.8: Pentax smc DA 50mm f/1.8: A prime lens by Pentax for APS-C cameras, 50mm f/1.8. The cheapest fast portrait lens for Pentax APS-C bodies. Specs - Maker: Pentax - Focal length: 50mm (prime) - Maximum aperture: f/1.8 - Made for: APS-C sensors - Mounts: Pentax K - Stabilised: no - Autofocus: yes What it frames like - On APS-C (Pentax K): like 75mm on full frame; f/1.8 gives about the depth of field of f/2.7 ...

From [Pentax smc DA* 16-50mm f/2.8 ED AL [IF] SDM: Pentax smc DA* 16-50mm f/2.8 ED AL [IF] SDM](/gear/lenses/pentax-smc-da-16-50mm-f-2-8-ed-al-if-sdm/): A zoom lens by Pentax for APS-C cameras, 16-50mm f/2.8. The original DA 16-50, replaced by the PLM version.

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