Is the pentax hd d fa 21mm f 2 4 ed limited dc wr worth it?

Here is what the site says about that.

From Pentax HD D FA 21mm f/2.4 ED Limited DC WR: Pentax HD D FA 21mm f/2.4 ED Limited DC WR: A prime lens by Pentax for Full frame cameras, 21mm f/2.4. A compact, weather-sealed wide prime for the full-frame bodies. Specs - Maker: Pentax - Focal length: 21mm (prime) - Maximum aperture: f/2.4 - Made for: Full frame sensors - Mounts: Pentax K - Stabilised: no - Autofocus: yes What it frames like - On full frame (Pentax K): as marked, 21mm. - On APS-C (Pentax K): like 32mm on ...

From Sensor sizes: Is full frame worth it?: For low light, events, and portraits with very shallow depth of field, yes. For travel, street, wildlife on a budget, and most hobby photography, a good APS-C camera with good lenses is enough, and you'll carry it more. Lenses and light matter more than the last stop of sensor performance.

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