Gray-black rings in sky/light background photos

Discussion in 'Beginner Questions' started by darlene_pfister, Apr 21, 2016.

  1. I have a Canon Rebel XS that I have used pretty extensively for a few years, and still consider myself a novice to DSLR technique. I have the basic lens, 18-55 mm, and a telephoto 55-250. The camera has automatic sensor cleaning at shutoff. In the past few months of use, I have noticed that when I shoot pictures of birds in the sky or an object that has the sky in background, I will get a gray to black ring or half-ring and some spots of same shade in the photos in the sky area, often surrounding the object to where I cannot crop it out, rendering the photo ruined. It occurs with both lenses. I have cleaned my lenses and the inner cam components as best I can access with no change. It happens with autofocus with or without the flash, as well as in manual and other modes, though it may vary in intensity trying other settings. I have googled extensively and have not found much about this issue. Is there anything I can try to resolve this, or has my camera reaching end of life? It is not noticeable in taking portraits, landscapes if I have more and darker subjects/objects, yet I often shoot birds, lighthouses, etc. I do not see an option to upload a sample photo from my PC? Thx
    00dtXb-562528084.jpg
     
  2. Though you've said you've cleaned the inside of the camera, this looks very much like a hair and dust on the sensor. If the spots and line become more pronounced as you increase the f-stop (higher f-stops), then I would definitely say it's on the sensor. There should be a menu setting for cleaning the sensor. Also, use a pristine sensor cleaner and do not scrub, but wipe in one direction only. Make sure to follow cleaning instructions carefully. Lastly, it may be difficult to see dust and hair on sensors unless you have a bright light and you move the light around.
     
  3. I agree that it looks like a hair on the sensor. It could easily blend in with a darker background but would show against light backgrounds, including the sky.

    The built in cleaning might not be enough. I use an airbulb to give the sensors on my Nikons a blast every now and then. Put the camera on Bulb, remove the lens, hold the camera pointing down so any dust/hair that comes lose falls out of the camera rather than back into it, and give a puff or two from an air bulb. (You can buy ones made for sensor cleaning at a camera store.) Hold everything carefully, of course -- you don't want to drop the camera and you don't want to jab the sensor with the air bulb.

    I would try the air bulb approach first before using anything where you actually touch the sensor.
     
  4. It could be a hair on the sensor, as has been suggested. But it's a fairly perfect circle of just more than 3.5 inches in diameter. Would a hair look that perfect? Also, wouldn't it move around with the sensor cleaning? Finally, Darlene says that this shadow doesn't appear in anything but images of the sky. If it was a hair on the sensor, wouldn't it be in every photo taken regardless of subject?
     
  5. While it is more difficult with some images than others it took me about ten seconds to rescue this shot using the clone tool, a few more seconds to work around the branches of the tree.
    It is obviously irritating to have such problems but photos are not 'ruined' by them if you learn to use a good editing programme.
    edit ...There is also a dust bunny in top centre which clone tool would removed if I had seen it :-(
    00dtay-562536284.jpg
     
  6. I'm pretty certain it's as Alfonso and Craig say. You can actually check it faster than I can write this post - take off the lens, set the shutter
    speed to several seconds (or 'B' setting per Craig), and look inside while the shutter is open. You will almost certainly see a small hair
    curling over the sensor.

    DO NOT try to remove it at this point ( other than using a blower from the outside) , if the shutter closes while you have a tool inside it could
    be damaged. Check your camera manual for specific instructions to open the shutter for cleaning, etc. - they will give the appropriate
    cautions. Note: also do not try to blow through your mouth - you're likely to get small droplets of saliva on the sensor, and if so, would need to get
    a "wet-cleaning" kit. Best of luck with it.
     
  7. Thank you for your responses. I will check the manual on sensors and try these approaches. I will look into more sophisticated editing techniques too.
     
  8. I wouldn't think of editing as a way around this. This is severe enough that you will be unable to clean this up successfully in the case of some images, at least at my (moderate) level of postprocessing skill. I think the first step should be figuring out whether the circular pattern is something on the sensor. If it is, then what you need is a straighforward sensor cleaning. It looks like you need one anyway, given that you have dust bunnies (the roughly round blobs) appearing even at f/9. You can either learn to do it yourself or take it to a shop. If the circle is NOT something on the sensor, then you have a larger problem that isn't obvious to me.
     
  9. BTW, don't use "bulb" or a long exposure to open the shutter.
    There is a "Sensor Cleaning" mode that will open the shutter but not energize the sensor (which can cause it to attract dust via an electrostatic charge):
    [​IMG]
     
  10. I may be a wimp, but I leave sensor cleaning to the experts ! My Pentax has a sensor cleaning function that vibrates the sensor each time I turn it on, which helps considerably, but every so often (maybe once a year, or more if I notice a large amount of detritus showing up in light areas on the image) I take it to my local friendly camera store, pay my £20 and have the job done professionally.
    Tony
     

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