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Af-s a rip-off?

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Thom Hogan said:
tvnewsbadge said:
Can anyone offer compelling reasons as to why Nikon went this route ?
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AF-S lenses (and AF-I before it) have motors in the lens that are matched to the lens. A phase detection AF system such as the ones in Nikon DSLRs knows both the direction and the amount the focus is off. With a precise match of motor to lens, the focus system can command the lens to move exactly where it wants it to. With a screwdrive lens, some lenses need two turns to get from one end to the other, some five. While there's a protocol that allows these lenses to move a fixed number of "units," it's not as precise as AF-S, and screwdrive motors vary in torque from camera to camera (consumer cameras have had low torque, pro cameras high). Thus non AF-S lenses tend to move close to the focus point, recheck, and then move in, and on some cameras move more slowly. One problem occurs with tracking moving subjects: the slight extra time with screwdrive may mean that it is now incorrectly positioned by the time it gets to the commanded point.
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I really don't see the concern about in-lens focus motors. Canon has long proved that this design works, and works well, even in consumer grade lenses. I have 25 year old consumer grade Canon lenses that I bought with my last film SLR that are still going strong after thousands of shots and much rough treatment. Nikon's move to AF-S is simply bowing to reality; in-lens focus motors work better, offer more user control, and faster, more accurate operation independent of the body they're attached to.
 
Any system in industry that requires precise positioning with an electric motor is going the same route. It is a much much more accurate positioning system than the old tiny little motor with shafts, couplings and gears to connect the motor to the lens ring and make it turn. The true afs system is completely different technology that does away with all the gears, shafts and couplings and makes the lens basically the motor with one moving part and one stationary part. In industry any new equipment that didn't use this technology would not sell at all - time moves on, we don't use horse and buggies much any more either.
 
From what I understand, Af-s lenses have the Automatic with manual override option as well as being quieter in operation.
 
To add, w/r/t AF-D:

The Nikon motor-in-body autofocus system, being mechanical, has inherent backlash throughout its chain of components to drive the focusing elements to a solution.

Without backlash, nothing moves. With backlash, the system will err.
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This is a key reason why the D300 (and up) bodies have AF Fine Tune capability, which has the ability to adjust for the system backlash inherent in AF-D screw-drive lenses.

Taking this a step further, this is but one reason why AF Fine Tune will usually wreak havoc on the focus ability of AF-S lenses; i.e., AF-S lenses have only the backlash in the AF-S motor which is corrected by the AF module solution calculated by the body.

[As an aside, ALL zoom lenses, Af-D or AF-S, should NEVER be AF-Fine-Tuned, unless you glue the zoom at ONE focal length - - after which, you might consider buying a prime at that glued focal length.]

Happy New Year!
 
pavi1 said:
....My prediction is that in the future you see a lot of AFS lens for sale with "broken focus motor"....
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AF-S is not exactly new technology thus I imagine we'd be seeing all those broken lenses by now.

I doubt AF-S optics will have the same long term durability of the older legacy lenses but I also believe the noticeably better accuracy and overall performance improvement on digital camera bodies is well worth the trade-off.

--
-Holmes
http://holmes.zenfolio.com/
 
So would you think that on newer bodies the motor will disappear? (Like the successor of the D300?) Just because AF-S is better, and it will save weight and bulk of the body.
 
Nikon claim from time to time AF-s can be focused much more accurate, as well as more quickly.

EXIF on Flickr reports AF-s focus distance to better than half a percent of focus distance - much more accurate than for screwdriver AF - so it seems difficult to deny the claim for focus accuracy is true.

Digressing does anybody know of an EXIF reader that reads Nikon's focus distance, other than using "more properties" on Flickr
--
Leonard Shepherd

Practicing and thinking can do more for good photography than buying or consuming.
 
Xscream said:
So would you think that on newer bodies the motor will disappear? (Like the successor of the D300?) Just because AF-S is better, and it will save weight and bulk of the body.
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No. I don't think the motors will disappear on newer bodies anytime within the next 10 years at least. The last non-AF-S lenses were introduced barely 10 years ago and Nikon needs to keep their new (semi)pro-bodies 100% compatible with technology less than 30 years old (this is just an estimation based on the newer Type-G design lenses which have removed the aperture ring and compatibility with the cheaper film cameras from around 30 years ago).

PS. I think that the in-body motor is faster than in-lens motor but this is only based on the dpreview review of the 50 F1.4G.
 
tvnewsbadge said:
There seems to be a body of opinion being expressd in other threads that the development of the Af-s lens line serves no purpose beyond a ploy by Nikon to force people to buy a motor every time they buy a lens.

The logic behind such an argument escapes me, but I have to say that I own both screw drive and Af-s lenses and they both work fine for me.

Can anyone offer compelling reasons as to why Nikon went this route ?
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THe AF-S lenses, if they have the ring type motor, are definitely much faster than screw drive AF. The super telephotos and zooms definitely benefit from AF-S design. The AF-S lenses themselves are not the problem, since all Nikon DSLR cameras can AF with them. It is the DSLR bodies that lack an in-body motor. They require AF-S lenses to AF. It is these bodies that Nikon is hoping will increase new lens sales.
 
There's a school on thought on other threads that Nikon could have put a screw drive motor in a body the size of the D40 without increasing either diminsions or weight, and at a cost that would not exceed fifty dollars.

The claim is made (by some) that this would be a good thing because it would allow the folks who bought entry level cameras to save a boat of money buying fromteh vast stock of used AF lenses currently available.

One example used is the 300mm f4, which one fella sez is available on Ebay in the neightborhood of 400 bucks, but goes for over 1k in the AF-s version.

Sounds good, but I've read in other places that the screw drive motor on entry level bodies is not the most powerful and therefore might not work as well higher end bodies with AF lenses.

Does that mean the AF-s lens with it's built in motor would be bertter choice for an entry level body with a lens like the 300 f4 even if the Ebody had the ability to use screw drives lenses?
 
Intrepid24 said:
To add, w/r/t AF-D:

The Nikon motor-in-body autofocus system, being mechanical, has inherent backlash throughout its chain of components to drive the focusing elements to a solution.

Without backlash, nothing moves. With backlash, the system will err.
--------------

This is a key reason why the D300 (and up) bodies have AF Fine Tune capability, which has the ability to adjust for the system backlash inherent in AF-D screw-drive lenses.

Taking this a step further, this is but one reason why AF Fine Tune will usually wreak havoc on the focus ability of AF-S lenses; i.e., AF-S lenses have only the backlash in the AF-S motor which is corrected by the AF module solution calculated by the body.

[As an aside, ALL zoom lenses, Af-D or AF-S, should NEVER be AF-Fine-Tuned, unless you glue the zoom at ONE focal length - - after which, you might consider buying a prime at that glued focal length.]

Happy New Year!
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So why then do modern Canon camera bodies have AF Fine Tuning as well? Their USM lenses have essentially no inherent backlash, just like AF-S lenses.

Backlash introduces a sloppiness in positioning that varies depending upon the direction in which the lens approaches focus. AF Fine Tuning compensates for bias in the focusing mechanism. But yes, AF Fine Tuning corrects for only one focal length, so can disrupt the error balance across all focal lengths.
 
tvnewsbadge said:
There's a school on thought on other threads that Nikon could have put a screw drive motor in a body the size of the D40 without increasing either diminsions or weight, and at a cost that would not exceed fifty dollars.

The claim is made (by some) that this would be a good thing because it would allow the folks who bought entry level cameras to save a boat of money buying fromteh vast stock of used AF lenses currently available.

One example used is the 300mm f4, which one fella sez is available on Ebay in the neightborhood of 400 bucks, but goes for over 1k in the AF-s version.

Sounds good, but I've read in other places that the screw drive motor on entry level bodies is not the most powerful and therefore might not work as well higher end bodies with AF lenses.

Does that mean the AF-s lens with it's built in motor would be bertter choice for an entry level body with a lens like the 300 f4 even if the Ebody had the ability to use screw drives lenses?
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An example of this might be the 80-400 with a D90 body vs the D300 or even D70 body. Works fine and fast with the D300's big motor, hunts a lot and is significantly slower with the D90's smaller motor and different AF system, works fairly well with the D70's medium size motor and higher end AF system.

Pretty much an AF-S lens is always a better choice from an AF standpoint because its performance is independent of the camera's mechanical ability to drive it.
 
VRII said:
mosswings said:
Pretty much an AF-S lens is always a better choice from an AF standpoint because its performance is independent of the camera's mechanical ability to drive it.
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Completely incorrect, the last three primes with AF-S, 105mm Micro VR, 50mm F/1.4 G and 35mm F/1.8 DX, all focus the same or slower speeds than their AF-D counterparts here is a link with testing performed by slrgear.com
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This might be true if AF speed were the only criteria one seeks with AF-S technology but it isn't. Reduction in operational noise, improved focus accuracy, ability to override/touch-up focus point are also valued attributes of the AF-S lenses thus even the slower versions may still be viewed as the superior choice when compared to their screw-driven counterparts.
--
-Holmes
http://holmes.zenfolio.com/
 
AF-S has several advantages.

AF-S motors allow you to grab the focus ring and tweak it. Try that with a lens hard coupled to the focus motor in your body and you may damage something. This alone makes them worth buying.

Without AF-S, your lenses focus at different speeds on different bodies depending on what motor it has. Very frustrating if you have one or two main bodies, and a lesser camera as a back up. Most of us can't justify buying 3+ high end cameras every couple years. I have personally had 2- 6 month old bodies die in the middle of an event (same defect), and shooting with my third body.

It makes the camera mount much cleaner. A motor is very difficult to pass from the body to the lens, electrical contacts are simple. Think about the implications for odd accessories such as extension tubes. Nikon was the last to break backward compatibility, and only on low end models so far. I would bet money this slowly moves up stream to higher end models.

Most of us value the glass more than the bodies. Generally you buy a lens and use it for many years, while bodies are traded (for now with digital) fairly regularly.

Nikon had to do this to compete with all the other manufacturers that had already moved the motors to the lenses on the low end bodies.

I stopped buying non-AFS lenses several years ago, except for some older great quality glass that I run across dirt cheap.

Don't listen to the uniformed.

sunflowerflyer
 
I agree. I have both AF-S and screw drive lenses, and while the screw drive lenses work fine, AF-S lenses ARE faster, and quieter, and more accurate. The OP did post BS to start a controversy.
--
JohnE
I have enjoyed taking these images: http://www.pbase.com/jpower

Below, Phoenix City Hall with Nikkor 10.5mm on D200

 
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