Focus motors: In-body vs in-lens

Started Apr 15, 2013 | Discussions
EKB
EKB
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Focus motors: In-body vs in-lens
Apr 15, 2013

Out of ignorant curiosity, what advantages (if any) are there to having a focus motor built into a lens rather than relying on the focus motor in the camera body?

Other than the obvious "will autofocus on entry-level bodies that don't have a focus motor" of course.

It seems obvious that putting a focusing motor in the lens will add to its cost and complexity. (Look at the price difference between Nikon's "D" vs "G" lenses.) Is the actual cost low enough for Nikon and other lens makers to routinely put a motor into all their new designs, just for the sake of "will work on a D5200 and below" - or is there some additional advantage that I'm overlooking?

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Leonard Migliore
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 15, 2013

EKB wrote:

Out of ignorant curiosity, what advantages (if any) are there to having a focus motor built into a lens rather than relying on the focus motor in the camera body?

Other than the obvious "will autofocus on entry-level bodies that don't have a focus motor" of course.

It seems obvious that putting a focusing motor in the lens will add to its cost and complexity. (Look at the price difference between Nikon's "D" vs "G" lenses.) Is the actual cost low enough for Nikon and other lens makers to routinely put a motor into all their new designs, just for the sake of "will work on a D5200 and below" - or is there some additional advantage that I'm overlooking?

Well, I'm kind of down on it. Maybe because my camera has a focus motor...

But it seems like the best AF-S lenses can focus faster than the best AF lenses; if you want to, you can put a pretty hefty motor in the lens. So that seems to be an advantage.

What I see as a disadvantage is that now you have all these additional failure points in the lens, especially lenses built to low price points. Nikon makes low-cost lenses for low-cost cameras and puts low-cost motors in them.

Given that Nikon lenses seem to cough and die on minimal provocation, I'm happier with lenses that have less stuff in them.

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Guidenet
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 15, 2013

EKB wrote:

Out of ignorant curiosity, what advantages (if any) are there to having a focus motor built into a lens rather than relying on the focus motor in the camera body?

Other than the obvious "will autofocus on entry-level bodies that don't have a focus motor" of course.

It seems obvious that putting a focusing motor in the lens will add to its cost and complexity. (Look at the price difference between Nikon's "D" vs "G" lenses.) Is the actual cost low enough for Nikon and other lens makers to routinely put a motor into all their new designs, just for the sake of "will work on a D5200 and below" - or is there some additional advantage that I'm overlooking?

There are many advantages to in-lens motors but they may all not apply to you or me. Moreover, there are more than one type on motors used in lenses. Some have more advantages and some are cheaper. Some advangaes might include

  • Faster focusing sometimes
  • Much more silent
  • Usually more accurate
  • Tend to hunt less

The fastest and most quiet tend to be the sonic ring type motors. You'll find them in lenses like the 70-200 f/2.8. There are also quiet rotary cluch systems that tend to be cheaper or tend to be better for video in that they maintain a steady speed.

Canon is using a new rotary technology called STM in some of their lenses which they claim is better for video transitions. I don't know.

I do know the older in-body motors and screwdriver type tend to be a lot noisier. Most of the tme, I don't care, but it can sometimes be important. For example on movie making, that whine is easily captured by the microphone and hard to get rid of in post.

Take care.

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slimandy
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 15, 2013

There are other advantages to AFS lenses apart from working on entry level bodies. The focus is quieter and smoother and offers MF override. My cams have motors built in but I'd still rather have AFS lenses.

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John Motts
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Re: Focus motors: In-body vs in-lens
In reply to slimandy, Apr 15, 2013

I can give an example that the focussing on the older 85mm f/1.4D was a lot noisier and less effective in low light than that of the newer G version.

That said, I don't know whether that"s down to the fact that the new lens has its own motor or just the newer technology.

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Stacey_K
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Re: Focus motors: In-body vs in-lens
In reply to slimandy, Apr 15, 2013

slimandy wrote:

and offers MF override.

This feature makes having a in focus motor worth it. I love AF+MF where I let the AF do it's thing. Yet if it misses the focus point I intended by a bit. I can simply touch up the focus and shoot. I miss being able to do this with my 180mm F2.8D. You have to pick one or the other.

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Cytokine
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 15, 2013

There is a lot to be said for screwdriver lenses, as the cameras are updated or a better camera used, the speed of the lens will follow suit, the 85mm 1.4G is borderline now and will not change, also there is the question of longevity, and budgeting for a future motor replacement. which could be expensive in say five years time.

John

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mironv
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Re: Focus motors: In-body vs in-lens
In reply to slimandy, Apr 15, 2013

slimandy wrote:

There are other advantages to AFS lenses apart from working on entry level bodies. The focus is quieter and smoother and offers MF override. My cams have motors built in but I'd still rather have AFS lenses.

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That's an only reason developmant went that way. I preffer in body motor system and with 15-18 years adavncemants in materials batterys if Nikon care to show what they can do they can put such a torque monster in pro body that AF lenses will fly. I used D1 along D2H and had al AF lenses no AFS there was no comparison D1 with incherent from F5 motor was driving my lenses like a Alaskan Husky's pull a slaid D2H was like sombody put few pudels to do a work of working dogs.

For a few % of users that use manual correction on AFS lenses It was not worth it but proggres is marching on. Funny part is that most AFS Nikon lenses are NOT AFS just gears are inside a lenses. they call them micro AFS and they suck. Only Ring type AFs ( bigger pro lenses) are true AFS anyway.

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windsprite
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Re: Focus motors: In-body vs in-lens
In reply to Stacey_K, Apr 16, 2013

Stacey_K wrote:

slimandy wrote:

and offers MF override.

This feature makes having a in focus motor worth it. I love AF+MF where I let the AF do it's thing. Yet if it misses the focus point I intended by a bit. I can simply touch up the focus and shoot. I miss being able to do this with my 180mm F2.8D. You have to pick one or the other.

Not necessarily.  If you don't mind doing the AF-ON/"back-button" AF method , you can have this feature on the 180/2.8 and similar lenses.

You just go into the menus and disable the AF on the shutter release button and set the camera to AF using the AF-ON button (or the AEL/AFL button, if your body doesn't have a AF-ON button).  Then you switch over permanently to AF-C and set the switch on the 180/2.8 to MF (also permanently).  Voila, you can autofocus using the back button while being able to use the MF ring any time.   No setting changes or button switches necessary.

AF-ON/back-button AF takes some time getting used to, but IMO it's far superior to using the shutter button to focus, because of the feature mentioned above, and also because you can stay permanently in AF-C and have all the benefits of that mode, plus AF-S and MF, without ever changing any switches or settings.  It's one of the best things about shooting Nikon.  I haven't changed out of AF-C in about three years.

One possible problem is that if your body doesn't have an AF-ON button, you have to use the AEL/AFL one instead, which means you have to switch AE lock over to another function button if you use it a lot.  I feel it's worth doing that to get all the benefits of AF-ON, but YMMV on that.

Julie

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slimandy
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Re: Focus motors: In-body vs in-lens
In reply to windsprite, Apr 16, 2013

windsprite wrote:

Stacey_K wrote:

slimandy wrote:

and offers MF override.

This feature makes having a in focus motor worth it. I love AF+MF where I let the AF do it's thing. Yet if it misses the focus point I intended by a bit. I can simply touch up the focus and shoot. I miss being able to do this with my 180mm F2.8D. You have to pick one or the other.

Not necessarily.  If you don't mind doing the AF-ON/"back-button" AF method , you can have this feature on the 180/2.8 and similar lenses.

You just go into the menus and disable the AF on the shutter release button and set the camera to AF using the AF-ON button (or the AEL/AFL button, if your body doesn't have a AF-ON button).  Then you switch over permanently to AF-C and set the switch on the 180/2.8 to MF (also permanently).  Voila, you can autofocus using the back button while being able to use the MF ring any time.   No setting changes or button switches necessary.

AF-ON/back-button AF takes some time getting used to, but IMO it's far superior to using the shutter button to focus, because of the feature mentioned above, and also because you can stay permanently in AF-C and have all the benefits of that mode, plus AF-S and MF, without ever changing any switches or settings.  It's one of the best things about shooting Nikon.  I haven't changed out of AF-C in about three years.

One possible problem is that if your body doesn't have an AF-ON button, you have to use the AEL/AFL one instead, which means you have to switch AE lock over to another function button if you use it a lot.  I feel it's worth doing that to get all the benefits of AF-ON, but YMMV on that.

Julie

I do that already but it's not the same thing. When you shooting with very shallow DOF the camera doesn't always focus at the exact point you want it to so a quick tweak to make sure you've nailed it is worth while. I find I mainly use it for macro and portrait. Very occasionally I also use it in low light, low contrast situations to avoid hunting.

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slimandy
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Re: Focus motors: In-body vs in-lens
In reply to Cytokine, Apr 16, 2013

Cytokine wrote:

There is a lot to be said for screwdriver lenses, as the cameras are updated or a better camera used, the speed of the lens will follow suit, the 85mm 1.4G is borderline now and will not change, also there is the question of longevity, and budgeting for a future motor replacement. which could be expensive in say five years time.

John

I've never had a motor fail, not even on the 17~35 that is said to be falable in that respect. It has been my most used lens over the past 11 years that I've owned it. If it does fail now I'd have had my monies worth, and I'd get if fixed.

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Dirk W
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Re: Focus motors: In-body vs in-lens
In reply to slimandy, Apr 16, 2013

I had broken motors in two 18-135s, I read here on this forum about a number of broken motors in AF-S 300f4s and found some links with weirdly behaving AF-S motors on youtube. I don't like that at all, I prefer owning good lenses that simply work with many generations of camera bodies without defects.

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mobi1
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Re: Focus motors: In-body vs in-lens
In reply to Dirk W, Apr 16, 2013

It is a commercial decision. Not having a motor in camera will make camera bodies cheaper. This will lead to many people upgrade from their P&S cameras.

Then people will start reading forums like this and will think "I must buy that lens". So manufacturers will recover lost camera revenue via lenses because lenses with motors will cost more and likely to fail beyond warranty period.

Lens should be made of glass - that's it. No VR or motors inside lenses. The VR and motor should be inside the camera and not on lenses!

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Re: Focus motors: In-body vs in-lens
In reply to Dirk W, Apr 16, 2013

Dirk W wrote:

I had broken motors in two 18-135s, I read here on this forum about a number of broken motors in AF-S 300f4s

The 300mm f4 AFS is another lens I have owned for many years with no problem. I don't think there is another lens in that range that would suit me better. Lovely IQ, very decent close-focus ability and it has a useful aperture ring. It's another example of a lens that has paid me back over the years and I'm glad I bought it. If it broke I'd have it fixed.

and found some links with weirdly behaving AF-S motors on youtube. I don't like that at all, I prefer owning good lenses that simply work with many generations of camera bodies without defects.

Me too. So far that's what I got. Must have had it 10 years.

I think the problem is you see a case highlighted because it went wrong but the many many users who don't have a problem are not likely to start a post saying 'my lens works as it should even afer 'x' years'. Your view gets warped by the minority because the majority have no need to speak out.

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Dirk W
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Re: Focus motors: In-body vs in-lens
In reply to slimandy, Apr 16, 2013

I think the problem is you see a case highlighted because it went wrong but the many many users who don't have a problem are not likely to start a post saying 'my lens works as it should even afer 'x' years'. Your view gets warped by the minority because the majority have no need to speak out.

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Yes I know, that can really happen. Anyway the two 18-135s are my own ones and I have read that it happened to quite a number of people but that is an old and cheap AF-S lens anyway. I bought the screwdriver 300f4 btw and am VERY happy about that lens.

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Leonard Shepherd
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 16, 2013

It is often reported in lens motors are more accurate and focus faster.

In the Nikon lenses brochure Nikon only say "extremely quiet, smooth and comfortable auto focusing"  - whatever that means!

In lens motors are definitely quieter, in my experience usually faster to focus and a little less prone to occasional miss focus. However lenses like the 50mm f1.4G are quite slow to autofocus.

When comparing D and G prices usually the G has optical improvements, sometimes nano coating and sometimes a larger front element to reduce digital corner vignetting.

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photoreddi
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Round and round and round we go...
In reply to mironv, Apr 16, 2013

mironv wrote:

...

Funny part is that most AFS Nikon lenses are NOT AFS just gears are inside a lenses. they call them micro AFS and they suck. Only Ring type AFs ( bigger pro lenses) are true AFS anyway.

Indeed, those round ring electronic motors are the way to go, and those in the know don't put stock in Nikon's screw driven lenses. They prefer to go with the SWM Bialy stock Nikkors instead.

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photoreddi
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Focus motors: In-body vs in-lens (AF-S, not micro motor here)
In reply to Leonard Shepherd, Apr 16, 2013

Leonard Shepherd wrote:

It is often reported in lens motors are more accurate and focus faster.

In the Nikon lenses brochure Nikon only say "extremely quiet, smooth and comfortable auto focusing"  - whatever that means!

It means what it says and it says what it means.

In lens motors are definitely quieter, in my experience usually faster to focus and a little less prone to occasional miss focus. However lenses like the 50mm f1.4G are quite slow to autofocus.

See, Nikon's brochure was accurate and you knew this all along, maybe because for whatever reasons you try to avoid skipping Marianne's replies, such as this oldie.

Marianne Oelund wrote:

Kuvasauna wrote:

Is the AF really not much faster than with 1.4D? Faster AF would be
my number 1 reason to upgrade.

It is in fact slower than the AF-D, at least on the D3. The trade-off is that you achieve a little better precision. In all of my tests so far, the consistency of focus is better with the 1.4G.

I would still say the AF is fast enough to follow action, but if you are expecting 200 f/2 class AF performance, you will be disappointed.
Reasons for "upgrading" to the 1.4G are
1. Quiet, precise AF with full-time manual override.
2. Better contrast and lower aberrations at widest apertures.

...

http://www.dpreview.com/forums/post/30398899

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Mark_A
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 16, 2013

I just did a related thread.

I am sure many people will have already pointed out that G does not mean in lens motor, rather it means no aperture ring. AFS means focussing motor in lens.

Anyhow.

I have five lenses and one focussing motor (in the body)

I suppose I could calculate the price of all of those lenses if they were AFS or not and then compare, might be interesting.

Mark

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Michael Otis
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Re: Focus motors: In-body vs in-lens
In reply to EKB, Apr 16, 2013

I have mostly AF-S lenses however I own the older Nikon 80-200mm f2.8 D with the screw driven auto focus sysytem.  I have found that with my D3 and its beefy battery pack it will auto focus very quickly however on my old D200 it focuses at a much slower pace.

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