Pentax DA* 300 f4

The DA* 300 f4 is the longest lens in Pentax’s current line-up. It’s a “star” lens (designated with an asterisk: *). Pentax began using this asterisk back in the early eighties to signify their special, high-end glass. The first star lens was the M* 300 f4, a compact 300mm lens of exceptional quality. The star assignation tended to apply mostly to Pentax’s long telephoto lenses, although it has been bestowed on some shorter glass as well, such as the FA* 24 and the DA*55. There are six lens in Pentax’s current “DA” line-up that received the asterisk: three primes and three zooms. All these star lenses are weather and dust resistant and have SDM focus motors in them. They are larger than most Pentax lenses. In that sense, they are comparable to the expensive professional lenses of Nikon and Canon.

Longer lenses use magnification to get closer to one’s subject. Inevitably, resolution is lost via the magnification, so that a 300mm lens can never be as sharp as a good 50mm lens. Resolution tests confirm this, as even high quality 300mm lenses such as the DA* 300/4 are significantly less sharp than even an average 50mm lens. This means that resolution is at premium with longer lenses. It’s also why the good one’s are so expensive. Where resolution is badly needed, every little extra counts. It also explains why, among higher end lenses, primes dominate. All things being equal, a prime will have a sharpness advantage over a zoom. It may not be much, but even a little extra sharpness can prove crucial as one goes beyond 200mm.

Another important factor determining image quality involves how well a lens renders colors and contrast. Cheap consumer grade telephotos not only let one down as to resolution, but they often have mediocre color rendition and uninspiring contrast. Take the following image, shot with the Tamron 75-300 f4-5.6:

At web resolution, it doesn’t look so bad (it received a huge amount of PP TLC). But now compare it to a shot from the DA* 300:

The DA* 300 shot jumps off the screen. It is not only sharper, crisper, with more “pop,” it also features more beautiful rendering, with distinctive colors and gorgeous bokeh. Extreme crops only confirm the superiority of the Pentax telephoto:

But all this extra resolution and improved image quality doesn’t come cheap: the DA* 300 costs around ten times the price of Tamron lens.

The resolution and superb rendering characteristics of the DA* 300 enables it to hold its own against shorter lenses; and while it may not have the same resolution as lenses such as the DFA 100/2.8 WR or the DA* 55/1.4, it can make images which look as good as its shorter brethren, particularly at web resolution:

Note the excellent bokeh: the background is completely blurred away. Here’s the advantage of a long lens in photos like this. Also note how close the lens allowed us to get to this nascent flower. Telephoto lenses often have a long minimum focus distances (MFD). Some of the older telephotos, such as the Takumar 300/6.3, have an MFD of nearly 18 feet. The DA* 300/4 will focus to four and a half feet, which is helpful for shots like this:

Bokeh is excellent in this lens. The f4 maximum aperture is hardly an issue as to achieving desired results:

Still, it’s resolution that’s critical in a long lens; and as the example above demonstrated, the DA* 300 does not disappoint. It’s fairly sharp from wide open and gets slightly sharper at f5 through f6.3. Consider the following image, taken at f5:

Now the ~100% crop:

Another example, also at f5:

Note not merely the commendable sharpness, but the narrow depth of field. Assuming one can get close enough (i.e, within 50 feet), at f5 it can be difficult to capture both the nose and the eyes of an Elk with equal sharpness.

While the DA* 300/4 is best suited to wildlife photography, because of its stunning color rendition and superb contrast, it makes a very fine landscape lens as well, at least on those few occasions when its long focal length can be useful in capturing the beauties of nature:

Nonetheless, the lens is at its best in wildlife photography. A 300mm f4 telephoto lens is often the optimal entry point into wildlife photography, because it provides the photographer with a lens that is neither too expensive nor too heavy. Lenses longer or faster tend to be at least three times the cost and at least twice the weight. Although 300 f4 lens are hardly lightweight (the DA* 300 weighs nearly two and half pounds), longer telephotos often weigh considerably more. The Pentax FA* 600/4, for example, weighs more than 15 pounds! The DA* 300/4 is just small enough to handhold. Yet, with its built-in tripod mount, it balances beautifully on a ball-head. Even better, the tripod mount swivels along the axis of the lens, allowing one to easily adjust from landscape to portrait orientations:

The DA* 300/4 has a 35mm equivalent, on Pentax APS-C DSLRs, of 460mm. That’s pretty damn close to 500mm, the recommended entry point for critter lenses. Even better, the excellent resolution of the lens allows for at least some cropping. In terms of usable results, the lens definitely tops what could be achieved with a 500mm lens on an FF sensor. The following image is cropped nearly 50%:

The DA* 300/4 features a “quiet” SDM focus motor. The motor is not especially fast and, while quiet, strikes me as entirely unnecessary. Lens motors give out over time and are not as durable or reliable as the old screw drive system. Nonetheless, for those who are uptight about noisy AF, there is no need to worry with this lens. You can take it to a wedding and shoot the nostrils of the bride without anyone being the wiser.

More images from the Pentax DA* 300 f4 lens: