The Pentax 01 Standard Prime ($199.95 direct) is a compact fixed-focal length for Q cameras. It boasts an impressive f/1.9 maximum aperture, making it ideally suited for use in dim light, and a field of view that’s roughly equivalent to a 40mm prime when paired with the Q7. Its small design makes the Q a pocketable camera, and even though it captures images that are a teeny bit soft around the edges, it sharpness in the center and at midway parts of the frame are quite impressive.
The lens measures just 1.8 by 0.9 inches (HD) and is incredibly light at 1.3 ounces. It accepts 40.5mm filters, the same size that are used for both Q zoom lenses. The lens can focus on objects as close as 7.9 inches, and at longer ranges you can achieve a shallow depth of field using the Q’s unique Blur Control mode. Its 40mm field of view is narrowed slightly to 47mm when paired with the older Q and Q10, as they feature image sensors that are smaller than the one found in the Q7.
I used Imatest to check the performance of the lens when paired with the Q7. At f/1.9 it delivers acceptable center-weighted sharpness, 1,822 lines per picture height. That’s better than the 1,800 lines we require for a sharp photo using that methodology. Edges are a little soft, about 1,500 lines. Stopping down to f/2.8 improves the overall score to 1,934 lines, and the edges are a bit better, 1,562 lines. The most consistent performance comes at f/4—the overall score is just about the same as it is at f/2.8, but edges sharpen up to 1,652 lines. If you’re shooting in JPG mode there’s no noticeable distortion, but if you opt to capture images in Raw your photos will have a noticeable 5 percent barrel distortion. A good Raw converter, like Lightroom 5, can correct for this—in the case of Lightroom via a single click.
If you’re a fan of the compact design of Pentax’s Q camera, and don’t mind eschewing the convenience of a zoom for some savings in size, the 01 Standard Prime is a worthwhile purchase. It’s acceptably sharp, although edges are a little bit softer than what we’d like to see at f/1.9, and its light-gathering capability will allow you to shoot with your camera at lower ISO settings. At $200 it’s not a trivial purchase, but it’s a very reasonable price for a fast prime lens. Just don’t expect the type of bokeh from this as you would an SLR lens—even the Q7′s 1/1.7-inch image sensor is going to limit your ability to control depth of field when not focusing very close or using the camera’s Blur Control system.
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