Is the pentax hd d fa 21mm f 2 4 ed limited dc wr good on aps c?

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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 Portraits: The lenses: - 50mm f/1.8. The cheapest great lens in photography, made for almost every mount. On full frame it's a natural, slightly tight view; on APS-C it behaves like a classic 75-80mm portrait lens. If you buy one lens for people, buy this. - 85mm f/1.8. The classic full-frame portrait lens: flattering perspective, soft backgrounds, comfortable working distance. On APS-C, a 56mm f/1.2 to f/1.4 plays the same role. - 35mm ...

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