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Old Jun 3, 2011, 3:27 PM   #1
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Default D5100 Autofocus?

I have gathered that the D5100, along with the d5000, d3100, and others does not have a focus motor in the camera while the D7000 and some others do. So my question is this....what does that mean? Does it make a difference? How many lenses would not be autofocus becuase of the lack of an internal motor? Does it affect autofocus speed?

Do most other camera makers make cameras with internal motors?
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Old Jun 3, 2011, 4:52 PM   #2
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There are many older Nikon lenses that will not autofocus with the lower-end Nikon bodies. However, there are well over a hundred from Nikon, Tamron and Sigma that will work just fine. In general, lenses focus faster when they have a built-in motor than when they use the mechanical link to the motor in the camera body. Unless you have a collection of old lenses that you are very fond of, you will most likely not be inconvenienced by the lack of a focusing motor in the camera body.
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Old Jun 3, 2011, 4:52 PM   #3
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When both the lens and the body have AF motors, the one in the lens is used, and few lenses are available both with and without AF motors, so there's no way to objectively judge which is faster.

The difference between having an AF motor in the body, and not having one, is your selection of lenses that will AF on it. Only Nikon's AF-S lenses will AF on bodies that don't have their own AF motors. Currently, 50 of Nikon's own lenses have their own motors, while only 21 don't. Most of Sigma's and Tamron's lenses have their own motors, but none of Tokina's do.

As it happens, none of Canon's bodies have AF motors, so any company that makes AF lenses for Canon bodies, puts a motor in them. Pentax and Sony put motors in all their bodies, so no one must put a motor in their AF lenses for those mounts, but some do anyway. It's only Nikon that has this relatively new mishmash of which bodies do and which don't, and while the number of AF lenses that have AF motors it growing steadily, there are still some lenses that rely on the body's AF motor, and if yours doesn't have one, then your AF lens won't.
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Old Jun 3, 2011, 5:07 PM   #4
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Quote:
Originally Posted by Iforgotmyname View Post
I have gathered that the D5100, along with the d5000, d3100, and others does not have a focus motor in the camera while the D7000 and some others do.
Right. The D40, D40x, D60, D3000, D3100, D5000 and D5100 bodies do not have a focus motor built into the camera body. So, you'll need to use lenses that do have a motor built into them (if you want Autofocus).

In the Nikon lineup, that means you'll need AF-S (Silent Wave Motor) lenses. In the Sigma lineup, you'll need HSM (Hypersonic Motor) lenses. In the Tamron lineup, you'll need to stick with lenses that specifically mention having a "Built In Motor".

All other Nikon dSLR bodies (D50, D70, D70s, D80, D100, D200, D300, D300s, D7000, D700, D2x, D3, D3s, etc.) have built in motors. So, you can use any Nikon mount Autofocus (AF) lens with them and still have Autofocus, even if they don't have a built in motor.

Quote:
So my question is this....what does that mean?
If you want Autofocus, you'll need to stick with lenses that have built in motors with the current entry level Nikon bodies.

With higher end bodies, you'd have Autofocus with any Nikon Autofocus lens (with or without a focus motor built into them), since the camera body has a focus motor built into it.

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Does it make a difference? How many lenses would not be autofocus becuase of the lack of an internal motor? Does it affect autofocus speed?
It would only make a difference if you wanted to use lenses that don't have motors built in. That's going to vary by individual and shooting needs.

There are *many* Autofocus lens models from both Nikon and third party manufacturers (like Sigma, Tamron and Tokina). So, it would be difficult to say how many of them don't have focus motors built in (especially if you consider older lens models and what's available on the used market).

For Nikon lenses, just look for AF-S to see the ones with focus motors built in. If they're AF versus AF-S, then you'd need a camera body with a built in motor to get Autofocus. Here's a list of current Nikon lenses (but, it doesn't include discontinued lenses that you may find on dealer shelves or in the used market, and it doesn't include third party lenses):

http://www.nikonusa.com/Nikon-Produc...ses/index.page

As for Autofocus Speed, you have to take each lens on a case by case basis; and when looking at lenses without built in motors, the camera body also makes a difference (higher end bodies will usually have faster AF motors built in).

Quote:
Do most other camera makers make cameras with internal motors?
They're really not directly comparable, as each manufacturer is a bit different in how their AF systems are implemented. For example, *all* Canon AF lenses have built in motors (their camera bodies do not). It's just a matter of what type of motor a lens has in it (some are faster than others).

Pentax and Sony AF systems are probably closer to how Nikon AF systems work. Their dSLR camera bodies have built in motors, and they have lenses with built in motors. Sony calls their lenses with built in motors SSM (Supersonic Motor). That's really the same type of focus system you find in Canon's ring type USM (Ultrasonic Motor) and Nikon's AF-S (Silent Wave Motor) lenses. Minolta also had some SSM lenses (and Sony bodies use the same lens mount system as Minolta AF cameras). Pentax refers to their lenses with built in motors as SDM (Supersonic Drive Motor).
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Old Jun 4, 2011, 4:19 PM   #5
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Most of Sigma's and Tamron's lenses have their own motors, but none of Tokina's do.
The Tokina 12-24 f/4 DX II has a built-in motor and is an excellent lens that would autofocus on all the cameras the OP listed. AFAIK, Tokina has not made any other lenses with built-in focusing motors yet.
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Old Jun 4, 2011, 5:29 PM   #6
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The Tokina 12-24 f/4 DX II has a built-in motor ...
Thanks for the correction.
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Old Jun 9, 2011, 1:18 PM   #7
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I would bet that most of the post-2008 lenses may be equiped with AF motors.

That year Nikon introduced the first motor-less D40.
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