Please help with autofocus!

Discussion in 'Photography Beginners' Forum' started by CThomas817, Nov 6, 2017.

  1. CThomas817

    CThomas817 TPF Noob!

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    I posted about this a few weeks ago and I'm sorry but I can't find the thread to update it!

    I am continuing to have issues with my Nikon D800 and my Nikon 85mm 1.8g lens. In certain situations, the camera struggles to focus, and since I have the shutter set to focus rather than release, the shutter will not trip. Of course, this occurs most often when I have the perfect moment, and particularly when I'm trying to focus on the eyes. I tried setting my shutter to release but without the camera relying on focus to take the shot, a larger percentage of my shots were not in focus (I shoot mostly children who are constantly moving). I have not taken it in yet as I'm sure it has something to do with my own lack of experience with this camera. I never had these issues with my much cheaper and simpler D3300 even when using it with prime lenses. Anyway, I am starting to notice a trend. As soon as late afternoon rolls around (3:00 - 4:00pm, Eastern time), this starts to happen. I am definitely not in what I would call a "low light" situation. I am shooting between 200-500 ISO with shutter speeds above 250. This was a sunny day, so late afternoon was still providing plenty of ambient light. I have tried playing around with my metering modes, bumping up my ISO, shooting wide open, etc., and that has not helped either.

    This particular shot was: ISO 500, f/3.5, 1/650th. I typically shoot close ups at f/2.2 but I was fiddling around with settings to see if it would change anything. I tried to take this shot about 5 times before the camera eventually grabbed focus and the shutter tripped. Luckily she stayed in one place for this one but there were many good opportunities I missed. This happened on and off for the duration of the shoot with these kids. I shot 4 other families earlier this same day and had absolutely no problems.

    I feel like there is enough contrast in the focal plane for the lens to focus, but I am really starting to feel that it has something to do with the light since it't always late afternoon or early evening that this occurs. What am I missing? To answer previously asked questions: No, the shutter was not on a timer. Yes, the lens was tightly secured. No, I did not accidentally change a setting.

    Desperate for help. I am really starting to get more serious about photography, and I cannot even consider having paying clients in the near future when I can't get my camera to work at the most desirable time of day to shoot!

    Thanks so much.

    Christina Chloe.jpg


     
  2. Derrel

    Derrel Mr. Rain Cloud

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    Switch to AF-C, with Release Priority, not Focus as the priority. YES, in AF-C, it WILL shoot some OOF shots, but it beats NOT shooting when the camera thinks it's OOF! If you set the lens to f/5.6 or f/6.3 or thereabouts, you'll HAVE enough depth of field that many times, what the camera might consider OOF at f/1.8 will actually be in-focus when the lens stops down to shooting aperture!
     
  3. jaomul

    jaomul Been spending a lot of time on here!

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    As said you can get success with using the af-c release priority, but it does sound like either your lens or camera has an issue. While f1.8 won't always be in great focus due dof, the camera should still focus and release if the lifting is good enough that you are at relatively low iso
     
  4. Tomasko

    Tomasko No longer a newbie, moving up!

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  5. Don Kondra

    Don Kondra Been spending a lot of time on here!

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    How many focus points are you using ?

    In the menu (a7) you can choose 51 or 11...

    Then set focusing mode to AF-S and move the focusing point to where you want it with the multi selector.

    Cheers, Don
     
  6. CThomas817

    CThomas817 TPF Noob!

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    Hi Derrel,

    I was in AF-C, but yes, I was in focus priority. I understand what you are saying though and I will keep trying. Thanks.
     
  7. CThomas817

    CThomas817 TPF Noob!

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    Hi Don. Using 51. My trouble with AF-S is that I often have subjects moving forward or backward out of the focal plane. I find AF-C to work very well on this camera in terms of tracking, of course, when it can focus. Actually, I switched to AF-S last time this happened and it didnt help, but then again, I was still using 51 focus points. I'll try using 11 next time.
     
  8. KmH

    KmH Helping photographers learn to fish Supporting Member

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    To search for previous posts/threads you have made:
    Hover yover your cursor over your user name in the upper right corner of the forum page.
    In the drop down menu click on Your Content.

    Or - Right click on your user name (it's blue because it is a link) and it will take you to CThomas817
    Then click on Postings and it will show you all your recent postings, including "Help with my Nikon D800!" you started on Oct 16.
    IIRC that thread got moved to the Nikon camera forum per the Photography Beginners' Forum description that reads in part: "For equipment specific questions, use one of the forums in the Camera Forum section of TPF."

    Or - in the upper right hover on Forums and in the drop down menu click on Search Forums.
    There you have several search options like Search Threads and Posts right above where you type in Keywords.
     
  9. Don Kondra

    Don Kondra Been spending a lot of time on here!

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    Another thing to try in AF-C, hold down the AF mode button on the front of the camera and switch to/try 9 points...

    Cheers, Don
     
  10. Designer

    Designer Been spending a lot of time on here!

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    Jumping around to random settings without a plan is going to be a crapshoot at best. If you luck onto a good setting by chance, you won't know why it works, nor can you easily duplicate it in future similar situations.

    That ISO setting is mostly irrelevant for exposure, so you can (IMO) set the ISO to "auto" and let it float.

    Your aperture at f/3.5 is still wide enough to give you a very thin DOF. I think you should set the aperture to 5.6 or thereabouts. (Check with a DOF calculator to verify that you will have adequate DOF) (I put one on my smart phone so I can check the DOF in the field as conditions change.)

    That shutter speed seems excessively fast for the light you had. Learn to hold your camera steady so you will not always be forced into a shutter speed that you might not want. There are plenty of tips and tricks on the internet to help you with camera hold.

    Set the AF to AF-C and 11 focus areas. With more experience, you can experiment with using all 51 areas, but you need to know how the AF system selects its preference in order to optimize the system for a given situation.

    Someone might suggest "back-button focus", but you've got enough to deal with just now, so you don't need to branch off into learning something else. I do not recommend any attempt to use BBF at this time.
     
  11. Designer

    Designer Been spending a lot of time on here!

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    Help with my Nikon d800!
     
  12. CThomas817

    CThomas817 TPF Noob!

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    Thanks for your advice. I wouldnt say I randomly change the settings. I try one thing at a time and if it isnt working, I return to my original setting so I always know what I have done. I have experimented with back button focus and it's not rocket science, but I really dont want to start using it consistently until I figure out whats going on with my AF. I find that the 51 points gives me more options for composition, but if going back to 11 will help in the immediate I will try that.

    I think the shutter was so fast because ISO at 500 really shouldnt have been necessary considering the given light. I think I should have been able to shoot at 200 with my speed around 1/250. I am not new to photography, but new to DSLR. I learned my camera basics over 12 years ago on a vintage 35 mm film, so while I am def not a pro, I don't think it's how I'm holding the camera. This autofocus issue has occurred even when using a tripod.

    I will consider your suggestions though, thank you for taking the time to respond. I will download a DOF calculator for sure!​
     

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