Sigma 30mm F1.4 Art DC HSM Lens for Pentax Equipped with the latest in lens technology, the 30mm 1.4 lens boasts a Hyper Sonic Motor (HSM), Super Multi-Layer Coating and a design featuring Thermally Stable Composite Material (TSC). The HSM ensures quiet, accurate and high-speed autofocus; the Super Multi-Layer Coating reduces flare and ghosting, while the TSC reduces expansion and contraction of the internal lens barrel A rear focus system prevents focus-dependent variation in aberration, making high-level image quality possible throughout the entire image. With their unchanging barrel length