# Nikkor 24mm 2.8 wont focus on D90



## tron (Jul 22, 2011)

Hey:

I have the following Nikkor 24mm 2.8 lens, I looked it up on the Nikon lens serial number site and it appears to be an Ai lens.  When I put it on my D90 body (which I just got today), it will not autofocus on the body.  Any reason why?

Site I looked the lens up on:
Nikon Lens Serial Nos

Pics of my lens:


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## Derrel (Jul 22, 2011)

Because it is a MANUAL focusing Nikkor.


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## table1349 (Jul 22, 2011)

Perhaps because it is not an autofocus lens.  http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/24mmnikkor/24mmf28.htm


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## 480sparky (Jul 22, 2011)

..................and there's no electrical contacts on the mount that the camera would use to focus it with?


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## KmH (Jul 22, 2011)

The D90 has a mechanical screw-drive focus mechanism that is used for AF lenses that do not have a focus motor in them, unlike Canon cameras that have had no mechanical connections between the camera and lens since 1987.

Nikon DSLR cameras still actuate the lens aperture with a mechanical body to lens connection too, which is why Nikon lenses all stop down to their smallest aperture when they are removed from the camera body and open to their max aperture when mounted.

For those unfamilar with Nikon's F-mount;






a view of the aperture actuating lever on the lens side of the connection:


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## quiddity (Jul 22, 2011)

sell?


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## tron (Jul 23, 2011)

Ah makes sense, Ive been shooting with a D40 for the past 3 years so I never really looked into what lenses autofocused since only the af-s ones did on the D40.

Can anyone tell me about the lens?  Ive read some reviews on it and it seems like a good lens.  Also for some reason when I manually focus it, it is blurry at infinity even though I get the green dot confirmation.  Everywhere from the hyperfocal distance up to infinity is pretty sharp though.


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## KmH (Jul 23, 2011)

tron said:


> Ah makes sense, Ive been shooting with a D40 for the past 3 years so I never really looked into what lenses autofocused since only the af-s ones did on the D40.


Oops! AF-S *and AF-I* lenses will auto focus on a D40.


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## table1349 (Jul 23, 2011)

KmH said:


> tron said:
> 
> 
> > Ah makes sense, Ive been shooting with a D40 for the past 3 years so I never really looked into what lenses autofocused since only the af-s ones did on the D40.
> ...



Wait, I think I see a thread here.  AF = Auto Focus.  Who would have thunk it???:lmao:


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## Garbz (Jul 24, 2011)

gryphonslair99 said:


> KmH said:
> 
> 
> > tron said:
> ...



But an AF lens doesn't autofocus on a D40. Bucking the trend Booyah


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## potownrob (Jul 24, 2011)

tron said:


> Can anyone tell me about the lens? Ive read some reviews on it and it seems like a good lens.


well, ken rockwell seems to like the AI-S version (this looks to be the the older Ai version; not sure what the differences are):
Nikon 28mm f/2.8 AI-s Nikkor

//dons fireproof suit


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## KmH (Jul 24, 2011)

potownrob said:


> tron said:
> 
> 
> > Can anyone tell me about the lens? Ive read some reviews on it and it seems like a good lens.
> ...


Here is some info that may help: Nikkor Lens Information by Thom Hogan


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## table1349 (Jul 24, 2011)

Garbz said:


> gryphonslair99 said:
> 
> 
> > KmH said:
> ...



"My D40  only autofocuses with the latest AF-S lenses, and also the the older, professional, AF-I lenses."  Wow, even Ken Rockwell knows this one.  Besides I was only speaking of the Family of Lenses, not the Genus or Species. 

Bada Bing... Bada Boom!


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