AF Question

Michael J.

Michael J.

Senior Member
I have a question and I am a bit confused :confused:

My D5100 needs lenses with AF cos the D5100 doesn't AF. If I buy a new camera which has AF how is the AF on the lenses or which is focusing - the Camera or the lens?
 
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Don Kuykendall_RIP

RIP :(
The D5100 does have Auto Focus. The difference is where the AF motor is. With the D5100 you have to have lenses with the motor in the Lens. With cameras like the D7000 the Auto Focus motor is in the Camera body. If I am not mistaken the lenses with the motor in the lens will work with the cameras like the D7000 .
 
Michael J.

Michael J.

Senior Member
Tracsoft - Don Kuykendall said:
The D5100 does have Auto Focus. The difference is where the AF motor is. With the D5100 you have to have lenses with the motor in the Lens. With cameras like the D7000 the Auto Focus motor is in the Camera body. If I am not mistaken the lenses with the motor in the lens will work with the cameras like the D7000 .
Click to expand...

OK The motor is in the lens D5100. But if I mount a non AF lens the D5100 doen't AF cos it doesn't have a motor in it, as I understand.

Now I bought lenses with AF. Do those lenses AF on a D7100. Or my question is - who takes over the lens motor or the camera motor?
 
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Bill16

Senior Member
I'm extremely new to all of this myself. But as I understand it the lenses with the motor in the lens are AF-S lenses, and the AF without the S are the lenses that need the motor to be in the camera body to work in automatic focus. But you can still use the AF lenses on the D5100 but only manual focus.
​I hope this helps, and that one of the real knowledgeable members will be able to explain it better for you. :)
 
Michael J.

Michael J.

Senior Member
My question is - which gear takes over on the D7100 when I use my 16-85 AF-s for example. The camera AF motor or the lens motor. The D5100 doesn't have an internal focus motor

Now the lens-motor is A-focusing on my D5100 cos the Camera doesn't have a AF motor.
 
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Bill16

Senior Member
I think the lens motor does the work, as long as the lens is AF-S. I think the camera motor only does the work when the lens is AF (without the motor in the lens). But I could be wrong, since I'm only a newbie at photography.
​
 
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Deezey

Senior Member
Wait. Editing because I confused myself.

And AF-S I believe will always focus in the lens. The camera body won't "take over". The only time the in body focus motor kicks in is in an AF only lens such as my 50 1.8D.




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FastGlass

Senior Member
The only time the camera will do the auto focusing is when the lense doesn't have an internal motor and the camera does. If the lense has an internal auto focus motor the lense will always do the auto focusing Because it will not have the mating screw to connect to the camera so the camera couldn't do it anyway. If the camera doesn't have an internal motor and the lense doesn't either than your only choice is manual focus.
 
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ladytonya

Senior Member
The Adorama video I just washed seems to indicate that the motor in the camera body takes over when you have both a motor in the camera and in the lens, at least that's how I understood it to work. It's a YouTube video that someone shared earlier on a thread and unfortunately I don't even remember where as I've been in tons of threads tonight, sorry. It was a very interesting video if you can find it! Try searching Adorame maybe....
 
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WayneF

Senior Member
Read page 197 of your D5100 manual (Compatible Lenses). It shows that that compatible lenses are the AF-S lenses. AF-S lenses have the focusing motor in them. Lenses that are not AF-S don't have the motor, and need the body to have the motor. But the D5100 does not have the motor, so you need AF-S lenses to have AF.
 
Michael J.

Michael J.

Senior Member
WayneF said:
Read page 197 of your D5100 manual (Compatible Lenses). It shows that that compatible lenses are the AF-S lenses. AF-S lenses have the focusing motor in them. Lenses that are not AF-S don't have the motor, and need the body to have the motor. But the D5100 does not have the motor, so you need AF-S lenses to have AF.
Click to expand...

I know that - I just want to know if the AF-S lenses are taking over the AF on A D7100 ort the camera
 
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WileyCoyote

Banned
siamthai1;
Your AF-S lenses will work just fine in the D7000, D7100 and also in my D90 body as I use the 18-105mm AF-S lens on my D90 with no problems what so ever.

Don't your AF-S lenses work on your D80 also?
 
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fotojack

Senior Member
WayneF said:
Read page 197 of your D5100 manual (Compatible Lenses). It shows that compatible lenses are the AF-S lenses. AF-S lenses have the focusing motor in them. Lenses that are not AF-S don't have the motor, and need the body to have the motor. But the D5100 does not have the motor, so you need AF-S lenses to have AF.
Click to expand...

Thank you, Wayne, for a very concise answer. I don't know why this has been so difficult to understand for some.
 
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fotojack

Senior Member
siamthai1 said:
I know that - I just want to know if the AF-S lenses are taking over the AF on A D7100 or the camera
Click to expand...

It's not a question of taking over so much, in that the AF-S lens is doing the focusing, regardless which camera is used. Let me make it as simple as possible:
Camera = D7100 = built in AF motor.
Lens = AF-S
AF handled by AF-S lens.


Camera = D40 = no built in AF motor.
Lens = AF-S
AF handled by AF-S lens.


Camera = D7100 = built in AF motor
Lens = AF
AF handled by D7100 with built in AF motor.


Is this clearer? :)
 
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WayneF

Senior Member
An AF-S lens simply does NOT have the screw drive that engages the body motor, i.e., the lens motor is always used.
 
Michael J.

Michael J.

Senior Member
fotojack said:
It's not a question of taking over so much, in that the AF-S lens is doing the focusing, regardless which camera is used. Let me make it as simple as possible:
Camera = D7100 = built in AF motor.
Lens = AF-S
AF handled by AF-S lens.


Camera = D40 = no built in AF motor.
Lens = AF-S
AF handled by AF-S lens.


Camera = D7100 = built in AF motor
Lens = AF
AF handled by D7100 with built in AF motor.


Is this clearer? :)
Click to expand...

Thumbs Up! Now I understand it. Thanks
 
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