We are scratching our heads a bit with the new Pentax HD 20-40mm f2.8-4 DA Limited WR Lens. Not because of image quality. In fact, the 20-40mm lens produces some beautiful imagery. The images look sharp--tack sharp, no less--especially in the center of the image. And we're not scratching our heads about the build quality either. The lens is solid and beautiful. However, if you are used to Limited Edition Pentax lenses it is not as heavy as some of their other lenses. The 31mm, the 77mm and the 55mm, for example, all feel like lenses that are built out of solid metal. This lens is not wimpy, though. It feels like it will withstand heavy and repeated use. But it doesn't have the exact same cold, metal feel as the other lenses listed above (you Pentax Limited users know what we mean). In addition to those great qualities, the 20-40mm lens is also HD (high definition) and WR (weather resistant). Those are some very promising features--especially to outdoor photographers. No, what really gets us scratching our heads is that the Pentax 20-40mm Limited lens is a variable aperture lens (f2.8-4) with a price point of $1000!
Here's the thing...Sigma unveiled its 18-35mm f1.8 constant aperture lens earlier this year (a very similar focal distance to the new 20-40mm Pentax lens). Although there is not a mount for Pentax just yet, Sigma is promising that there will be one very soon (or if you simply can't wait then you can always utilize the conversion service). We tested the Sigma 18-35mm f/1.8 on a Canon T5i and got amazing results. Imagine what it would be like on a K-5 II, a K-5 IIs or a K-3 that has better image quality to begin with! The Sigma 18-35mm lens is a heavy duty lens, but it is bigger than the Pentax (if this is of high importance to you). Remember, the Sigma has a constant f1.8 aperture. That's amazing. But to be fair to the Pentax lens, the Sigma lens is not weather resistant. The Sigma has fantastic image quality and great build with a price point of only $800. Now you have yourself a winning lens!
So, why would Pentax release a similar focal length lens with a variable aperture for a higher price point? That's why we're scratching our heads. We are guessing that Pentax started making this lens before the Sigma lens was announced. However, at the point Pentax finds out that Sigma created a constant aperture f1.8 zoom lens with a similar focal length, we would assume they would want to rethink one of two things: either the variable aperture or the price. The easier thing to rethink is the price. Based on the competition we would pay about $600-$700 for this lens, maybe even $750-$800 because the name Pentax Limited is imprinted on it and it's weather resistant. Hopefully Pentax/Ricoh will have a big sale on this lens for the holiday season, making the decision of which to buy a little more challenging. One can hope.
One other minor complaint about the lens is the included screw-on lens hood. The lens hood is small. We mean really, really small. So small that we're not sure it would do a good job of keeping out extraneous light. The lens cap does maintain the black velveteen fabric on the inner portion of the cap. We so love the feel of this!
Here are some sample images taken with the Pentax 20-40mm f2.8-4 Limited lens married to the Pentax K-5 IIs. The image quality is great. We love the way it renders pictures with great color, contrast and clarity. We found the edges to be a tad bit soft, but on par with zoom lenses of its caliber. We tested the lens on the maximum aperture for the 20mm and 40mm focal lengths and it retained complete sharpness. Nitpicking the image quality produced by this lens leads us to want the circular bokeh in the defocused areas to be a little smoother, but that's not a deal breaker. Overall we love the lens. It's just the price we think should be smaller.
The two images below were taken at a 40mm focal lenth, ISO 100. Both are very sharp.
The next image was intentionally shot into the sun with extreme contrast of the tree to test for chromatic aberration. As you can tell, there is some slight purple fringing around the limbs where the sun is most intense, but given the circumstances we think the lens did a great job! This is nothing a little tweak in post production couldn't fix. These images are SOOC and have not been retouched in any way.