▁ED ▁[ IF ] ▁SD M ▁is ▁a ▁super tele ▁prime ▁l ens ▁for ▁Pent ax ▁K - mount . ▁It ▁uses ▁Pent ax ' ▁silent ▁SD M ▁motor ▁for ▁aut of ocus ▁on ▁compatible ▁cam eras ▁( K 1 0 D ▁and ▁K 2 0 0 D ▁up wards ), ▁and ▁has ▁Quick ▁Sh ift ▁F ocus ▁to ▁allow ▁manual ▁adjust ments ▁in ▁aut of ocus ▁mode . ▁ ▁Re ception ▁ ▁Phot oz one ▁review ed ▁the ▁l ens ▁fav ou rab ly , ▁stating , ▁" in ▁terms ▁of ▁resolution ▁and ▁contrast ▁the ▁l ens ▁is ▁able ▁to ▁produce ▁very ▁good ▁results ▁straight ▁from ▁the ▁max . ▁a pert ure ▁setting " ▁and ▁" me chan ical ▁quality ▁of ▁the ▁l ens ▁is ▁absolutely ▁exception al ▁thanks ▁to ▁high ▁quality ▁materials ▁and ▁se als ▁against ▁dust ▁and ▁mo ist ure ". ▁Of ▁the ▁ul tr ason ic ▁aut of ocus ▁motor , ▁they ▁wrote ▁that ▁it ▁" works ▁like ▁a ▁b ree ze ▁- ▁it ' s ▁both ▁fast ▁and ▁almost ▁silent ." ▁Over all , ▁they ▁concluded ▁that ▁the ▁l ens ▁is ▁" high ly ▁des irable ▁l ens ▁for ▁sports ▁and ▁wild life ▁photograph ers ." ▁ ▁Color F oto ▁wrote ▁the ▁l ens ▁had ▁out standing ▁sharp ness ▁over ▁the ▁entire ▁frame , ▁even ▁wide ▁open , ▁and ▁Pop Photo . com ▁said ▁that ▁" images ▁shot ▁in ▁the ▁field ▁were ▁satisfying ly ▁contrast y ▁and ▁sharp ." ▁ ▁References ▁ ▁S MC ▁Pent ax - DA