What is the difference of ultrasonic motor, stepper motor, and electromagnetic drive? Which one of these are lens-based or screwdrive? What are the advantages of lens-based servo over screwdrive and vice versa? Are camera body normally built to have autofocus motor or normally lens-based?

I'm looking for

  1. Technological difference
  2. Usage difference
  3. Price and availability
  4. Advancement in recent years
  • \$\begingroup\$ Possible duplicate of What does STM mean on a Canon lens? \$\endgroup\$
    – Philip Kendall
    Apr 23, 2016 at 14:32
  • 1
    \$\begingroup\$ Sounds like questions for a research paper :) \$\endgroup\$
    – Itai
    Apr 23, 2016 at 14:33
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    \$\begingroup\$ If you are interested in recent developments perhaps you should include the development of linear electromagnetic focus motors in your question. For more about what they are (as well as a very brief survey of the history of other focusing methods) see lensrentals.com/blog/2016/04/a-look-at-electromagnetic-focusing \$\endgroup\$
    – Michael C
    Apr 23, 2016 at 17:08
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    \$\begingroup\$ See: photo.stackexchange.com/questions/74876 \$\endgroup\$
    – inkista
    Apr 23, 2016 at 17:42
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    \$\begingroup\$ I feel there might be demand for a comprehensive answer detailing different technologies, different manufacturers' brand names, etc. The linked questions are quite Canon-specific. \$\endgroup\$
    – JohannesD
    Apr 24, 2016 at 16:02


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