Autofocus Not Working

edited September 2012 Posted in » Nikon D5100 Forum
I bought my camera August 8, 2011. The autofocus isn't working but has until recently (within the last few days).

It happens with the 18-55mm, which is the lense I primarily use. When I push the shutter button halfway the frame doesn't readjust, it stays blurry. Zooming with the lense makes it worse. I know very little about cameras, especially digital. The auto focus is what I rely on to get crisp photos. I am a real estate assistant and take photos of homes, inside and out, and up to now the camera has been terrific. Any step by step help would be great!



  • edited October 2012
    I would say that your motor in the lens has gone out or the contacts have been bent. Can you try another lens? If that works then you will need to buy another lens. If more than one lens does the same thing then I would take your camera to a service shop. Hope this helps!
  • edited October 2012
    @MLRoth If you can hear the lens' motor working but the picture still looks blurred through the viewfinder, check the dioptre setting (the one that focuses specifically for your own eyesight). It may be that the settings moved, so it will never look properly focused for you until you reset it?
  • edited November 2012
    I'm not trying to insult your intelligence, but I had this same problem two weeks ago and I took the camera to Best Buy (it's under warranty). The employee showed me that on the lens itself is a button that can be moved to A or M. Mine was on M meaning manual so the lens wouldn't auto adjust. I really really thought my camera was broken and I've been using this camera for over a year. Needless to say I felt really stupid and just moved the button back to A. It's worth a try. I think mine had flipped to A in my camera bag or something.
  • edited April 2013
    @ebp913 - whoever you are, you're my personal hero right now! I'm on a once-in-a-lifetime trip around the USA, visiting beautiful national parks. I'd been getting great photos but for the past few days I've not been able to take pictures as my autofocus hasn't been working. I was getting really frustrated and a bit down about it. I think my lens must have flicked from automatic (A) to manual (M) like yours did as I just clicked it back, and presto, my camera works again!

    I know I'm a moron for not thinking of it, but at least I didn't waste a lot of money on a new camera which was what I was just about to do!

    Thank you so much for posting, whoever you are!
  • edited July 2013
    I have the same problem with the auto focus on my Nikon D5100. It was working perfectly with my AF 50mm lens, then I got creative and on the menu and changed AF to manual. Now I can't seem to change it back! There is no separate M/AF buttons on my AF 50mm lens, (unlike on my 18-75mm zoom) and when I try to navigate the camera menu to select the focus icon, it just skips over it. I've tried re-setting the shooting menu, but that doesn't do anything either. Please help!
  • @Dusk_Fire - If you have the older 50mm f/1.8D (the one without the M/A - M switch), it won't autofocus with the D5100. The newer 50mm f/1.8G will because it has a focusing motor built into the lens itself.
  • edited August 2013
    Thanks Moose, I understand perfectly. I think I had been using autofocus with my zoom lens successfully and then changed it to manual to be more creative. Then later I changed lenses to the 50mm lens, and because it said AF in the manual that came with it, I thought I could use autofocus on it and couldn't understand why that wasn't an option on the camera menu. I see now that my lens is the older f/1.8D. Slightly annoying that they sell it as an autofocus lens when it doesn't work with the Nikon D5100, but I guess it will work as autofocus with other models of camera. Thanks again for your advice.
  • @Dusk_Fire - Yep, I agree, lens compatibility is a bit confusing with Nikon DSLR's...especially for their entry level models like the D5100. For future reference, look for the 'AF-S' label in the lens specs to ensure auto-focus works with your camera. All the best! :)
  • edited May 2014
    I'm having a difficult time with my Nikon D3200 18-105mm lens. It won't focus automatically or manually.
  • edited May 2014
    Try the button on the left of the lens that says A] [M. Mine was turned to M for Manual focus instead of A for Auto focus. Super simple and a no cost to fix!
  • edited May 2014
    It still won't work, it is a disaster. I cant use it anymore. Even though I turn it to or it won't work. The camera can't catch a picture properly. What should I do?
  • edited May 2014
    Toggle the focus switch on your lens to M (for manual) and then turn the focus ring on the lens to achieve focus. There’s no way that this doesn’t work unless your lens is broken/defective.

    Toggle the switch on your lens to A (for auto). Make sure you’re in a well-lit area. Turn your mode dial to Auto. Half press the shutter to see if it locks focus. If not, then perhaps the AF motor on your lens is defective. To verify this, mount another lens to test.
  • edited July 2014
    I was experimenting with the manual mode and faced the same problem. Issue is resolved now.
    Here's what worked for me:
    --- Shift dial to manual
    --- Select focus mode. Set it to AF-C i.e. Continuous Servo-AF
    --- Back to Auto mode.

  • edited October 2014
    I bought the D5100 November 2012. Autofocus worked fine until recently, so I had to finally read the manual. I found the A/M switch on the lens and set it to A. I believe it had been switched to M, somehow. No help. After much experimenting, I found that in viewfinder mode the lens will not autofocus, but in Live view mode, it will autofocus. So the lens motor and contacts must be OK. Perhaps there is some setting I have overlooked? Any ideas?
  • edited October 2014
    Do you hear the autofocus motor working in either live or viewfinder mode? How do the pictures themselves look?

    In Live View, there is a fair amount of focus adjustment in the display which is not actually being performed by the lens. When you move from a near to a far subject in Live View, you should first see some focus adjustment in the display. Then when you push the shutter button you'll hear the lens make a full adjustment, and the display will compensate again.

    If you can't hear and see the lens itself autofocusing, it's not doing it. If possible, you should find another AF-S lens to try and see if anything changes.

    If I understand this correctly, AF is achieved in different ways with Live and Viewfinder views. In Viewfinder mode, the image to be focused is influenced by mirror adjustment, whereas in Live view the mirror is out of the way altogether, and focusing is done on the image plane itself.

    What I don't know is whether there is some internal switching here that also might influence whether the AF motor works in one mode and not the other.

    If the motor is working but you get badly focused images in viewfinder mode, I'd suspect a mirror problem needing repair. If the motor is working and images are good but you can't see clearly, then the problem is likely in the viewfinder itself; either a dislodged viewfinder screen or a diopter issue.
  • edited October 2014
    I've had your issue happen to me before. That is, the phase detect autofocus doesn't work while the contrast based autofocus works just fine.
    Try this first. Unmount your lens. Gently use a brush to clean the contact pins on the lens, and also do a quick brush on the contact points on the camera body.
    Then mount the lens and test it out. It worked for me. If no luck, you may have to bring it to a Nikon service center.
  • edited October 2014

    Just out of curiosity, do you know whether or not the switch of autofocus modes when you go to live view also involves a hard switching of the lens' AF? In other words, when you flip the mirror, is it likely that the AF motor will stop working, or start working, when you do this? On line information on this detail is scanty.

    If I read the details right, the actual connection point at the lens is the same, so it seems odd that a contact failure at the lens interface would have an effect. Given how complicated the whole system is, nothing would be that surprising.
  • edited October 2014
    I honestly don't know. When it happened to me, I brought it in to a Nikon service center and they couldn't figure it out on a preliminary exam. They wanted me to leave it with them for repair. Since I wasn't comfortable with paying for repairs when they couldn't even tell me what's wrong or give me a quote, I took my camera home.
    I resigned to shooting with just Live View. Out of the blue, I decided to clean my lens and camera. That's when I discovered the issue was fixed.
  • edited October 2014
    I thought of another thing to look at. It may be of little help but might get closer to finding out what's happening where.

    This is assuming that the lens's autofocus motor is working in Live View and is not working in Viewfinder View, and that cleaning the lens contacts does not solve it.

    Put the lens in manual mode, viewfinder view, and focus manually. Does the focus confirmation light come on when focus is achieved? If it does not, this would indicate that the focus sensor itself is not working. In that case, nothing you do with the lens will help. If the focus confirmation light works (and the rangefinder if that option is on), then the focus sensor is working, and something else, perhaps a bad lens contact, is at fault.
  • edited December 2014
    There is really only the following reasons this is happening:
    - The lens needs to be on the A for auto focus
    - The Lens is broken, so try another
    - The lens is mistaken for an auto when it may only work as manual

    The best advice if the above reasons do not work is exactly what ArunaPradeep stated in his post. Worked like a charm!!!

    ArunaPradeep on July 6
    "I was experimenting with the manual mode and faced the same problem. Issue is resolved now.
    Here's what worked for me:
    --- Shift dial to manual
    --- Select focus mode. Set it to AF-C i.e. Continuous Servo-AF
    --- Back to Auto mode."
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