Pentax DA 18-55 f3.5-5.6 II

The Pentax DA 18-55 II f3.5-5.6 is an update of the original kit lens designed specifically for Pentax’s APS-C digital cameras. It gives the 35mm equivalent of a 27mm to 84mm lens — a very useful range. Fans of Pentax regard the DA 18-55 as the “best kit lens.” Even if true, this is (whether intended or not) a rather backhanded compliment: sort of like saying, best last place team. Kit lenses involve compromises in optical quality, build quality, and speed in order to keep the price of the lens down. While the DA 18-55 may have slightly better build quality than either the Nikon or Canon 18-55 lenses, it’s not clear that it’s optically better than either, or, if it is better, whether it really matters. A mediocre lens is a mediocre lens. That one lens is a little less or a little more mediocre hardly matters.

The problems with the DA 18-55 are numerous. It’s slow, soft at the long ends of the zoom, not particularly sharp in the intermediate focal lengths, exhibits mediocre contrast and color rendition, tends toward extreme border softness, particularly at infinity focus, and (perhaps most importantly) is outclassed by every lens in Pentax’s current lineup with which it shares a focal length. Consider, as an example, the following two images:

The first image was taken with the DA 18-55 II, the second with the DA 12-24. Of course, they were taken at different times with different lighting; but for what it’s worth, the 18-55 was shot in May during the late afternoon, when the sun was at a more suitable angle for landscape photography, while the 12-24 shot was shot in June at around 1:00 pm, when the glare of the sun, particularly as it is reflected by snow, is at it’s very worst. Be that as it may, the contrast and color rendition of the DA 12-24 is significantly better than what we find in the optically challenged DA 18-55. Here’s a closer look:

A polarizer was used on the DA 18-55 II, because it was needed (the sky, which has been darkened in post, would be completely washed out without it). The DA 12-24, with it’s excellent color rendition, doesn’t require a polarizer. It gets the sky right without such accessories.

How about another example:

This time, the DA 18-55 II is being compared with the Pentax SMC 28/3.5, a lens introduced in the mid-seventies. Both pics were shot using the exact same B+W ND 3.0 filter. It may seem unfair to compare the 18-55 to a prime lens, but this does give one an idea of the limitation of the Pentax kit lens compared to other comparably priced lenses. Moreover, in this pic, the DA 18-55 is shot very near it’s “sweet spot”: i.e, at 35mm, f11. Yet the older lens exhibits much more microcontrast and deeper, richer colors, leading to a significantly more impressive photo.

How about another comparison with the DA 12-24?

You’ll notice immediately the DA 18-55 II is “colder.” That’s intentional. I had to make it colder to avoid overly yellow greens. No such trouble with the 12-24. Cheaper lenses have difficulty rendering darker greens, which they tend to represent with an unattractive yellow cast. They can be “de-yellowed,” as it were, in post, but then you get an image that is a tad bluish and cold.

Another comparison, involving ~100% crops, to judge sharpness:

As can be seen, the DA 12-24 is sharper (though not by much). The real difference is the micro-contrast and color rendition, which leads to a much more pleasing image — an image, in short, that is more vivid, that has more snap or “pop.” Also note the much richer blues in the stain glass window produced by the DA 12-24. This relates to the light-transmission abilities of the lens. The DA 18-55 blocks off nearly 20% of the blue spectrum. The consequence is that it struggles to do justice to blue colors, rendering rich blues in hues that amount, quite literally, to a pale imitation.

The main virtue of the DA 18-55 II is that it is cheap and it covers a useful range, from wide angle to short tele on an APS-C camera. It’s main defect is that it’s slow and optically-challenged. For this reason, it’s not well suited for artistic photography. As a portrait lens, it’s too slow. At 55mm, it’s an f5.6 lens; which prevents the sort of separation via narrow DOF preferable for portrait photography (or any photography that requires a narrow DOF). Consider the results of 18-55, shot at 55mm (@ f6.7), compared to that shot with a 50mm prime lens (@ f2.8):

As a landscape lens, the color rendition, lack of corner to corner sharpness, and mediocre micro-contrast renders the DA 18-55 II a sub-optimal choice. Indeed, the 18-55 only works well as a snapshot lens. It’s eminently serviceable for such work. As an artist’s tool for making stunning images, however, it leaves much to be desired. Most photographers, if they aim to produce something spectacular, need better glass!