The Pentax SMC FA 43mm f/1.9 Limited lens ($749.98 direct) is a compact all-metal prime lens that can be used with Pentax D-SLRs and the K-01 interchangeable lens camera. When used on an APS-C camera it captures a 64.5mm equivalent field of view, which makes it a long normal or short telephoto lens. Of course, you can also use it on 35mm film cameras, where it serves as a true normal lens—its focal length is equal to the diagonal measurement of a 35mm film frame.
The lens is really small. It measures just 1.1 by 2.5 inches (HD), although its height is extended by about a half-inch if you opt to use the included screw-in metal hood. It weighs in at 5.5 ounces, which may seem heavy for its size until you realize that the barrel is made of metal rather than plastic. There’s no internal focus motor, instead the lens has a screw-drive system—which makes autofocus noticeably slower than lenses with built-in motors. The filter thread is 49mm in size, and there’s an aperture ring that allows you to use the lens with full aperture control on a vintage Pentax film body or a compact interchangeable lens camera via a third-party adapter.
Imatest shows that the lens is incredibly sharp when tested with the Pentax K-30 . Even at f/1.9 the lens resolves more than 2,000 lines per picture height—higher than the 1,800 lines required for a sharp image. Stopping down to f/2.8 increases the score to 2,700 lines, and the lens crosses the 3,000 line mark by f/4. This is even more impressive when you consider the size of the lens. It’s not the thinnest lens on the market, but it is one of the few pancake designs with an aperture that is faster than f/2.
If Pentax had a full-frame digitial body in its lineup, the SMC FA 43mm f/1.9 would be an easy pick for our Editors’ Choice award, despite the rather slow and noisy autofocus that goes hand-in-hand with a screw-drive system. Unfortunately, you can only mount it to an APS-C digital body at this time, which limits its field of view, making the lens more of a short telephoto. Many Pentax shooters have turned to the SMC FA 31mm f/1.8 Limited as a standard-angle prime for this reason—it’s equally impressive from an optical standpoint, but is bigger, heavier, and more expensive.
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