Pentax-DA* 55mm F1.4 Review
Design and Handling
The Pentax DA* 55mm F1.4 lens was introduced in 2008. It is designed for digital cameras, and as such cannot be used on film cameras because it does not cover the full-frame image circle. The DA* 55mm field of view is more like a 83mm on a film camera because the APC-S sensor is 1.5x times smaller than a 35mm image. The DA 55mm is constructed with a plastic composite shell and metal mount. The lens is heavier and longer than the DA or FA 50mm lenses, it weighs 13.2 oz. and is 2.6 inches long.
The focus ring is located at the front of the lens and it requires a little less than 1/2 of a turn from the minimum focus distance of 17.7 inches to infinity. The focus ring is about one inch wide and does not turn when you utilize the lens SDM autofocus. As mentioned previously the DA* 55mm has a KAF3-mount, so if the lens is mounted on a camera body that does not support the Supersonic Drive Motor, the lens will need to be focused manually. Below is picture of the rear mount, notice that there is no provisions for the camera’s screw drive. This would affect cameras older than the K10D with firmware version 1.30.
The lens, like all DA* lenses, does allow Quick-Shift Focusing, which permits you to manually focus the lens at any time. The focus ring, when utilized is very smooth and well dampened. The lens is very quick and responsive when used with the K-5’s autofocus. The front element uses a 58mm filter.
The lens has a number of features that are noteworthy. First, the lens is tightly sealed which makes it dust and weather resistant. Unlike the consumer DA weather resistant lenses, the DA* 55mm has a black O-ring rather than a red one on the bayonet mount. Second, the lens has a floating focus mechanism that allows the rear element to stay stationary, while the remaining lens elements move during focusing. Third, the lens has rounded diaphragm blades which create a more circular aperture for smoother bokeh. The lens also has an auto-focus/manual-focus selector switch on the side.
The lens has a small sealed window in the middle of the lens that displays the distance in feet and meters. Above is a picture of the sealed window. The front element moves about one inch from focusing at infinity to the minimum focus distance, as you can see from the pictures below. The front element does not protrude beyond the end of the lens, so it will not affect the placement of a filter. Below is a picture of the front element at infinity, on the left. On the right is a picture of the lens at minimum focus distance.
The lens hood utilizes a bayonet mount. The lens hood can be stored over the lens to save space. The lens hood has a small window that can be removed to adjust a polarizing filter. The only disadvantage with this arrangement is the window has to be removed prior to placement of the hood on the lens. The lens hood also has a rubber edge that provides some shock resistance if you accidentally bump the lens.
