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philm35

USA, US
26 posts

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philm35 Registered since 25th Jan 2004
Thu 21-Mar-13 11:57 PM

I have an old 24-120mm 3.5-5.6D Nikkor AF zoom that I bought during the film heyday to use with my N90s. It's still a great walking around lens, but it has a problem when mounted on my new D800.

When the lens is zoomed in to 100mm or greater, the autofocus "hunts" for the correct focus. The autofocus overshoots the focus point, backs off to undershoot it, and repeats the process several times until it settles in the right spot. Sometimes it never settles in the right spot, and just keeps cycling back and forth until I give up on it. At shorter focal lengths, the lens nails the focus instantly.

Here's the weird part... The lens focuses perfectly on my D300 and on my old N90s. And all other lenses (that I've tried) focus perfectly on my D800.

What's the deal?

Thanks,

--Phil

agitater

Toronto, CA
4551 posts

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#1. "RE: Weird Autofocus" | In response to Reply # 0

agitater Gold Member Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2014 Nikonian since 18th Jan 2007
Sat 23-Mar-13 12:30 PM

It may just be a minor lens contact problem. Try using a bit of 90% or stronger isopropyl alcohol on a swab to clean the contacts on the end of the lens. There might be just enough oxidation to fool the D800 for some reason, but not your D300. It happens. Also, make sure the D800 body mount lens contacts are clean and unimpeded.

BTW, use only an alcohol-damp swab, not a wet dripping swab. Make sure you don't leave any cotton swab bits behind. Only takes a few seconds to clean the contacts and it might do the trick for you.

Do not use rubbing alcohol. It contains a bit of oil which will leave a transparent film behind and impede contact. Pure isopropyl only - 90% or higher. Do not use electrical spray degreaser or spray contact cleaner anywhere near a camera or lens unless you spray it on a swab (well away from your gear) and then use the swab on the electrical lens or body contacts. Spraying any sort of electrical cleaning or degreasing compound of any kind in the vicinity of a lens coating or open camera body is a very b-a-a-a-a-d idea.

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ajdooley

Waterloo, US
3387 posts

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#2. "RE: Weird Autofocus" | In response to Reply # 0

ajdooley Gold Member Nikonian since 25th May 2006
Sat 23-Mar-13 01:16 PM

Phil -- Read and follow Howard's advice. It's worth thr 9 years ofNikonians membership you have invested! Electrons can be fickle things when it comes to moving between pieces of equipment. BTW, I sold my 24-120 when I moved from the D200 to a D700 because it wasn't sharp in the corners IMHO. I hope yours is better.

Alan
Waterloo, IL, USA
www.proimagingmidamerica.com

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philm35

USA, US
26 posts

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#3. "RE: Weird Autofocus" | In response to Reply # 2

philm35 Registered since 25th Jan 2004
Sat 23-Mar-13 01:25 PM

Thanks, Alan and Howard.

I did try cleaning the contacts with some DeOxit contact cleaner (not sprayed near the lens, of course!). Unfortunately, it made no difference. I'll give the Isopropyl alcohol a try. I suspect the problem may be internal to the lens, since the issue only occurs when the lens is zoomed in nearly all the way.

Alan, I had the same suspicions about the 24-120's sharpness when I moved up to the D800. Would the lens hold up to 36 megapixel scrutiny? I was actually pleasantly surprised... It is remarkably sharp in most situations... even wide open.

I'm still planning to upgrade to the 24-70 2.8 and the 70-200 2.8 VRII soon... but I'll keep the old 24-120 for less formal shooting occasions when I don't want to carry a lot of hardware around. May have to send it to Nikon for repair, though, if I cleaning the contacts doesn't solve the focus problem.

--Phil

agitater

Toronto, CA
4551 posts

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#4. "RE: Weird Autofocus" | In response to Reply # 3

agitater Gold Member Donor Ribbon awarded for his very generous support to the Fundraising Campaign 2014 Nikonian since 18th Jan 2007
Sat 23-Mar-13 03:08 PM

Phil - If you've cleaned the contacts with DeOxit, I doubt you'll do any better with isopropyl alcohol. So you're right I think - it's probably a lens issue.

If you love the 24-120 focal range and if it has served you well over the years, I strongly suggest that you owe it to yourself to try out the much newer Nikkor 24-120 f/4 VRII. It is a remarkable match for the D800 and it has been on my own D800 since last May. I purchased the newer 24-120 f/4 when it first came out three years ago and it has never let me down. The newer design is wonderfully sharp, contrast is wonderful, color is excellent and it's fast. A well built lens and one of Nikon's better efforts. The difference between both of the old Nikkor 24-120 designs (non-VR and original VR) and the the newer f/4 VRII version is literally like night and day.

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gaopa

Hartwell, US
784 posts

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#5. "RE: Weird Autofocus" | In response to Reply # 4

gaopa Silver Member Nikonian since 28th Jul 2003
Sun 24-Mar-13 06:25 PM

>If you love the 24-120 focal range and if it has served you
>well over the years, I strongly suggest that you owe it to
>yourself to try out the much newer Nikkor 24-120 f/4 VRII. It
>is a remarkable match for the D800 and it has been on my own
>D800 since last May. I purchased the newer 24-120 f/4 when it
>first came out three years ago and it has never let me down.
>The newer design is wonderfully sharp, contrast is wonderful,
>color is excellent and it's fast. A well built lens and one of
>Nikon's better efforts. The difference between both of the old
>Nikkor 24-120 designs (non-VR and original VR) and the the
>newer f/4 VRII version is literally like night and day.


AMEN! I had the older version of the 24-120 and recently got the new f4 one. Oh my, what a difference! I'm lovin' that lens on my D800. Cheers, Bill P.

Georgia Opa

G