Is the pentax hd da 40mm f 2 8 limited good for portraits?

Here is what the site says about that.

From Pentax HD DA 40mm f/2.8 Limited: Pentax HD DA 40mm f/2.8 Limited: A prime lens by Pentax for APS-C cameras, 40mm f/2.8. A pancake lens that keeps the camera small. Specs - Maker: Pentax - Focal length: 40mm (prime) - Maximum aperture: f/2.8 - Made for: APS-C sensors - Mounts: Pentax K - Stabilised: no - Autofocus: yes What it frames like - On APS-C (Pentax K): like 60mm on full frame; f/2.8 gives about the depth of field of f/4.2 there. ...

From Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR: Pentax HD DA 20-40mm f/2.8-4 ED Limited DC WR: A zoom lens by Pentax for APS-C cameras, 20-40mm f/2.8-4. The only zoom in Pentax's Limited range, in a small metal barrel.

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