Is the pentax hd d fa 50mm f 1 4 sdm aw good in low light?

Here is what the site says about that.

From Pentax HD D FA* 50mm f/1.4 SDM AW: Pentax HD D FA* 50mm f/1.4 SDM AW: A prime lens by Pentax for Full frame cameras, 50mm f/1.4. Pentax's high-end, weather-sealed full-frame standard prime. Specs - Maker: Pentax - Focal length: 50mm (prime) - Maximum aperture: f/1.4 - Made for: Full frame sensors - Mounts: Pentax K - Stabilised: no - Autofocus: yes What it frames like - On full frame (Pentax K): as marked, 50mm. - On APS-C (Pentax K): like 75mm on full frame; f/1.4 ...

From Pentax HD D FA* 85mm f/1.4 ED SDM AW: Pentax HD D FA* 85mm f/1.4 ED SDM AW: A prime lens by Pentax for Full frame cameras, 85mm f/1.4.

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