Autofocus

edited October 2014 Posted in » Nikon D3100 Forum
My image is darker on one side. Why is this happening?

Comments

  • edited October 2014
    To begin with, it is unclear between title and text whether your problem is one of darkness (exposure) or blur (focus). An image to see would be a big help. If you can find a site that hosts free images (dropbox, shutterfly, or the like) you can post the link here.

    I am guessing that there is a language problem here. The more you can describe, the easier it will be for others to figure out what is happening.

    This camera has a vertical shutter, so problems with the shutter or with using the wrong flash setting will usually appear as a black band at the bottom or top of the image, not the right or left. Using flash at too high a shutter speed will produce an image with an unexposed area (black) at the bottom. Most shutter problems will result in a fairly sharply defined area of bad or missing exposure, and the area will show horizontally across the frame.

    If you have a bad exposure area that is not sharply defined like that, I'd suspect a problem with the sensor.

    If the problem is not one of exposure but of focus, then I'd suspect the lens. A lens that has been dropped or damaged, or is just plain defective, may have a glass element out of alignment. This will often result in focus being off on one or the other side. If you can find another lens to borrow and take a couple of pictures, you will find out immediately whether or not this is your problem.

    In order to provide the best information, it would help if you can take a number of pictures at different settings. Use as wide a selection of shutter speeds, ISO settings, and other variables as you can. Try the lens at minimum and maximum aperture to see if it varies there. If it is a zoom lens, try it at its extremes to see if it varies. The more you can tell us about what it does or does not do, the easier it will be to help.

  • edited November 2014
    Hi,
    Thank you very much for your effort to help me. I'm really very sorry for not giving proper details. I thought to upload the photos in this forum, as there were no options for it, I didn't know how to proceed. After reading your post, I have followed your advice and uploaded them in dropbox. I am a beginner. Indoors with less light, sometimes I get this problem. Outdoors I have no issues. I took this photo in auto mode.
    With regards,
    Shalini

    (see here)
  • Before I think too much into this, are you certain those are not shadows that your camera is capturing?
  • edited October 2014
    The first picture looks fine, and the second has a shadow that is different from the last two. The last two have a ragged-edged shadow, which is certainly not a shutter malfunction, and I doubt it is a sensor malfunction, but it warrants a further look.

    If you are using the built-in flash, I suspect a shadow is appearing from a conflict between the flash and the ambient light, or that the ambient light has more shadow than you notice when simply looking at it. A photograph is less forgiving than the eye, and the built in flash is not very good at sorting out complex lighting. It's a decent fill flash, but minimal for many jobs.

    What I would suggest first, as an experiment, is to try indoor pictures again. This time with the flash disabled, and at a high ISO, or with ISO at at auto setting that allows it to go high. The pictures may be noisy and not very good to keep, but by eliminating the flash as a factor, it removes one possible problem and makes it easier to diagnose.

    For an experiment, try using a high ISO, and set the camera to aperture priority mode, with the lens aperture first set at about f/5.6, and then again with the aperture set at about f/16. Now take a couple of pictures (it does not matter of what) indoors in something that looks like fairly even lighting. A blank wall would be quite good enough. The camera's meter should compensate enough to give you a picture (though it might be poorly lit and blurry), but the result should show very quickly if there is a malfunction. If you shoot an evenly lit scene, the result should be pretty even. If you shoot in different directions, any oddity of light should look different in the different pictures. If the shadows keep being in the same place no matter where you aim the camera, then there may be a problem. Otherwise, you may just be dealing with difficult lighting situations.

    Remember this is a digital camera, and it's durably made, so do not be shy about taking some bad pictures just to test and erase them. Experiment freely with different light and different settings.
  • edited November 2014
    Thanks for the review. I will try your suggestions and get back to you soon.
  • edited November 2014
    I tried as per your advice and uploaded a photo in the following link.
    (see here)
    I am unable judge anything. DSC1047 and 48 were taken at auto ISO and with flash off.
    DSC1049 and 50 were taken at ISO 1600, f/5.6 aperture mode.
    DSC1051 and 52 were taken at ISO 1600, f/16 aperture mode.
    Kindly let me know whether is there any malfunction or error on my skills and settings.
  • edited November 2014
    Well, those blank spaces look to me as if they are pretty evenly exposed, and the exposure itself is about as expected. When your meter sees a single shade, it "thinks" it should render that as light gray, which it has done. All are similar exposures, which means that your camera's meter is compensating correctly for your changed apertures.

    It all looks good here, and my guess is that your earlier problem came from unexpected shadows or flash problems.

    If you want to continue your search, try next to take the same blank wall with the flash on. You should see more or less the same featureless wall, perhaps a little lighter in color. Depending on distance, it may be a little brighter in the middle, but not lopsided.

    If your image passes the above test (no need to upload if it does), then I think you can safely say the camera is behaving well, and your main task in future will be to light indoor subjects more evenly.

    Good indoor shots of kids can be a challenge to light well. You might consider looking further at this site, as the host here has come up with some helpful instructions on settings for this, and they are not very expensive.

    By the way, they're a lovely looking bunch of kids there!


  • edited November 2014
    Hi Bruto,
    Thank you very much for your kind review. I am happy to hear that there's nothing wrong with my camera. I will try the other tests also.
    With regards,
    Shalini
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