Originally posted by AlexZav the Pentax 35mm HD macro, the Sigma 18-35, or, budget wise, the Samyang 35mm that is the cheapest as well the fastest but manual.
Here, the Rokinon 35mm f1.4 (same lens) is $70 more than the DA 35mm Ltd. The Sigma Art zoom and 35mm f1.4 prime are roughly double the price of the DA 35 Ltd. My recommendation is the same as other posters here, the DA 35 f2.4 AL is one-third the price of the DA Ltd. Admittedly, the Limited is a true macro lens, but minimum focus distance is less than 4 inches away from the end of the lens, so it is awkward to use for macro work.
Originally posted by AlexZav the 35mm in the K3 will be more of a normal lens than the 50mm
If you want to take group portraits or there isn't much room to back up from your subject, 35mm is a very useful focal length on APS-C. Having said that, I only use my DA 35 AL in low light and/or I want faster than f4. I was going to say the versatility of the DA 18-135 trumps the DA 35 in every other situation, but sometimes you want a less intrusive lens on your camera. I was sitting about 5 feet away from my brother and trying to get pictures of people who don't like being photographed.