Can someone explain to me why the Rokinon 24mm lens has a focus motor? Quoting from LensHero's page on the lens:

Generic motor built-in focus motor

From what I understand, only autofocus lenses will focus automatically (using either a lens motor or a motor in the camera body), but manual focus lenses do not have the capability of focusing automatically at all. Having a motor on such a lens seems pointless, doesn't it?


2 Answers 2


A focus motor without autofocus can be useful for manual remote control of the focus.

For your particular example, the Rokinon 24mm, I think that the information on the Lenshero webpage is simply wrong.

  • \$\begingroup\$ Interesting thought! Do you know of any lens which actually has such a feature? \$\endgroup\$
    – mattdm
    Mar 3, 2016 at 11:26
  • 1
    \$\begingroup\$ No, not at all for DSLR. Some surveillance cameras have it. Compact and video cameras without a physical focus ring and optional manual focus do it. But admittedly, these are all some kind of cameras instead of standalone lenses. In my opinion, it would be useful for cinematic lenses. They often come with the outer gear to attach an external drive instead. \$\endgroup\$
    – bogl
    Mar 3, 2016 at 12:29

You're entirely correct: there's no point whatsoever having an autofocus motor in a manual focus lens. So why does LensHero says it has a focus motor? It's just wrong, plain and simple.

(Occam's Razor and all that - if you see something stupid, always look for the most likely explanation).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.