Quick question about auto focus bodies and lenses

[Forkie]

A thought just occured to me that I can't word satisfactorily for Google to bring up an answer.

If one were to use a lens with an auto-focus motor in it on a body that also has an auto-focus motor in it, will the camera use both motors and speed up the time it takes to achieve focus, or will the camera simply use just one of the motors?

 

[SCraig]

It just uses one of the motors. In my D90 I think it's the one in the lens but wouldn't swear to it.

 

[djacobox372]

Nope, the motor in the camera body doesn't link up with motorized lenses.

 

[KmH]

If one looks at the flange of the lens mount on an AF-S (or AF-I) lens, they will see that the spot where the screw drive would engage the lens focus mechanism is blank, making the in-the-body focus motor useless.

The electronics in an AF-S (or AF-I) lens let the camera know to disable the screw drive focus motor and instead route the AF module focusing commands to the AF motor in the lens.

I am always amazed that few people really look at their gear to discover how it works.

Have you ever noticed that when you remove a lens from a Nikon DSLR, that the lens stops down as far as it possibly can, and when the lens is remounted, the aperture opens to as wide as it can.

Have you ever opened and closed the aperture of an unmounted Nikon lens manually with the aperture actuation lever on the mount flange?

 

[Derrel]

If one looks at the flange of the lens mount on an AF-S (or AF-I) lens, they will see that the spot where the screw drive would engage the lens focus mechanism is blank, making the in-the-body focus motor useless.

The electronics in an AF-S (or AF-I) lens let the camera know to disable the screw drive focus motor and instead route the AF module focusing commands to the AF motor in the lens.

I am always amazed that few people really look at their gear to discover how it works.

Have you ever noticed that when you remove a lens from a Nikon DSLR, that the lens stops down as far as it possibly can, and when the lens is remounted, the aperture opens to as wide as it can.

Have you ever opened and closed the aperture of an unmounted Nikon lens manually with the aperture actuation lever on the mount flange?

I am amazed that somebody who professes to know how the gear works would label that a "Blank AF-S AF screw drive recess". Surely you must be kidding if you think that is what that recess is for!!! Are you kidding?? In one sentence you try and make people feel bad or stupid for not looking at their gear and "how it works" and then in the same post, you put up a wildly MIS-LABELED, erroneous piece of nonsense?

That "Blank AF-S AF screw drive recess" in your graphic has NOTHING AT ALL to do with autofocusing!!! Dude--that "recess" has been machined into the back of over 65 million F-mount lenses, made over multiple decades...that recess is where the spring-loaded pin goes INTO when ANY F-mount lens is fully bayonetted onto any F-mount body!!

Perhaps the next time you try and correct people for their ignorance, you might wish to make sure of what you're talking about, okay? It looks foolish to chastise others for "failing to look" to see how their gear actually works...and to then make a ridiculous error when a five-second look at your own gear will show what that recess is for!!!

Somebody needs to make a new F-mount graphic and label things correctly...and this time "really look at their [your] gear to discover how it works."

Once again, the supposed "Blank AF-S AF recess" you are talking about engages with the lens locking pin--located at 3 o'clock... the screw drive is located at 7 o'clock on the body's lens mount...cough..cough...it's on manual focusing lenses too...cough...cough...

 

[Forkie]

Thanks KmH, I've done both the things you asked as a matter of fact. Neither caused a light bulb to appear above my head with the answer. Perhaps my mechanical knowledge is not up to scratch, but I'll get over it. A little more patronisation next time would be just great.