The best part is that the current Pentax KA mount is a variation of the original K mount that was introduced in 1975. There are more than 40 years’ worth of K-mount lenses and the majority of these lenses can still be mounted on the Pentax K70, although some will limit the use of some camera features. The result is that there are thousands of used lenses available, many at great prices, meaning that you can add quality glass to the front of your camera for a very reasonable price. So there are fantastic Pentax lenses, third-party lenses and 30 years of legacy lenses that will work with the Pentax K70.
lenses were first badged as . The Takumar branded lenses were well respected for their line of Super Takumar, which designated the high performance coating applied to the lens as well as the optical formulas used to make them. The majority of the industry at the time was still satisfied with the variations of the "plumb" coating process and later some of the two and three layer processes as well. Asahi Pentax soon introduced the Takumar Super-Multi-Coated line of lenses which was a 7 layer process as the industry had just caught up with similar forms of 5 layer multi-coated optics. Eventually Asahi Optical and Pentax slowly shifted much of their lens production under the Pentax name and transitioned some of the successful designs that were first introduced under the Takumar name to use Asahi/Pentax badging as well as beginning to use the "smc" abbreviation. Eventually the Asahi partnership disappeared and the Pentax name became solely used. Pentax lenses saw many feature changes to answer the market, such as: incorporating "Auto-Aperture" with the M42, the light weight and compactness with the 'M' series, Aperture Priority overrides with the 'A' series, and Auto-Focus with the 'F' series. Modern Pentax lenses for have seen the elimination of the aperture ring completely as found on Pentax DA and D-FA series lenses. They use the (and its variants, KAF2, KAF3 and KAF4). All of these lenses have an feature, either operated from the camera body or from an internal SDM motor. Pentax compatible lenses are also made by third-party companies.
Another feature which sets Pentax lenses apart from other manufacturers is that many of their lenses, like their medium- to high-end camera bodies, are weather-sealed, allowing for their continued use in poor weather and wet locations.
There's not much to add that our tests don't already show: it's an inexpensive lens that fills a gap in Pentax's lineup. Stopped down, it provides excellent results for sharpness, but many people will be buying it for its ability to shoot at Æ/1.8, where it offers only mediocre performance. If you need to shoot at wide apertures, you are better served with Pentax's more expensive options; if you are looking for a portrait lens that you'll stop down to at least Æ/2.8, then this could be a good alternative for you.