Pentax K 50 f1.2

The K 50 f1.2 is the fastest lens Pentax ever made. It was produced when Pentax switched from the m42 screwmount to the K-Mount. It is extraordinary lens, one of Pentax’s very best. It features excellent color rendition, a gorgeous bokeh, and some of the most beautiful, luminescent rendering you’ll ever find in an SLR lens. Wide open, it’s not terribly sharp, but that was true of all f1.2 lenses of its period. Indeed, a test by a German publication in the early eighties found the Pentax lens to be sharpest wide open of any of the 50mm f1.2 SLR lenses available at the time. The following is an example of an image taken at f1.2:

Note that while the stigma of the flower (the center of the focus) is not exactly “tack” sharp, that there’s still plenty of detail. DOF however is so thin that very little else stays in focus, and the outer parts of the flower evaporate into blur. And indeed, one of the difficulties of shooting with this lens is that, wide open, the depth-of-field is so narrow that it is easy to miss your focus point, which leads to pictures that look soft and complaints about the lens’ performance. But the narrow DOF is actually one of the lens’ best features, as it enables artistic imagery straight out of the camera. With such a lens, the out-of-focus areas can become as important as that which is in focus:

Consider the following image:

Very little post-processing was used with this image (just a few minor tweaks to exposure and contrast). Most lenses could not come close to that kind of rendering.

One neat trick, especially when photographing flowers, is to extend the lens, allowing for closer focus. When the minimum focus distance is under one foot, the depth of field is quite literally razor thin, allowing for some astonishing photos:

Notice how in the second and third photos the stem holding up the flower is almost completely blurred out, making it seem as if the flower is suspended in mid air. Notice also how the background is entirely blurred away.

Stopped down, the lens takes on a different character. It still renders beautifully, but the depth of field widens and the lens becomes very sharp. Note the following photo, taken at f8, following by 100% crop of same photo:

Here’s another example at f8. Notice the beautiful colors and the exquisite, luminous rendering of detail:

Nonetheless, it’s at its faster apertures that the K 50/1.2 really distinguishes itself. More photos taken at or near f1.2:

Even when not at f1.2, the lens has a marvelous bokeh, with extraordinarily vivid colors as well: