Re: Why a motor on a 300mm Pentax lens?

[James Schenken <jds@xxxxxxxxxxxxxxx>]

Some of the lenses were made with internal motors and are labeled DA lenses.  They seem to be backward compatible with Pentax bodies with the builtin motors. Pentax called this Supersonic Drive Motor lenses (SDM).

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On Oct 14, 2014, at 6:09 PM, PhotoRoy6@xxxxxxx wrote:

Pentax K-II cameras has it lens focusing motor in the camera body. However some Pentax lenses have motors in the lens . Why?

Roy