Third party have many different abrievation though..
Tokina has at-x... Sigma has HSM and OS for it's motor and IS... Tamron has USD for it motor and VC to replace IS
so, the sigma 18-200 is meant for aps-c cameras.. So af-s is relatively the same..
HSM = Sigma's Hypersonic Motor. But it is not Sigma's only lens motor. They also had another version of their lens motor that is NOT HSM (a slower and older motor).
There is no AF-S for Sigma. AF-S is a Nikon strictly Nikon mount spec. It not just referring to Nikon's motor, but also the entire electronics spec for Nikon Lens. The wave motor in Nikon is referred to as SWM = Silent Wave Motor.
Nikon AF-S and Sigma HSM are NOT relatively the same, especially here we are talking about Canon EOS mount. Want to say something, say it accurately. If cannot, might as well don't say anything.
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