 Jonathan Sabo |
Spot in photos
My pictures are great, I love it, untill one day I discovered that in all my photo's there is a black spot in the exact same spot on all the photos. Normally I'd say, ok clean the lens. I ... think I did, probably not as well as I could, but here's the thing that makes me thing a little harder. It only appears when the aperture setting is as high as it goes. As you lower the f-stop the more out of focus this black spot becomes. When I look through the viewfinder, I do not see this black spot, but it is in the digital preview in back after I take it.
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Alan N. Marcus |
Hi Jonathan, The spots are caused by dust or the like on the cover glass of the CCD chip. Such spots generally show prominent when the subject is mundane like blue sky or in your case white walls/ceiling. An air gap exists between the cover glass and the surface of the sensor. The lens projects an image of the outside world onto the CCD sensor. These light rays must pass through the cover glass. If dust spots or other opaque substances are on the cover glass, the obstruction casts a shadow on the sensor. Now consider that inside the camera, light rays that form the image are handled by the lens on a point for point basis. Thus the rays as they pass through the lens bear a resemblance to the shape of an ice cream cone. Stated another way, a cone of light, large in diameter, originates from the lens and converges to a tiny point at the surface of the CCD chip. Now the diameter of the cone of light is a variable dependent on the lens aperture used. If the lens is operating at a large aperture (large opening tiny numeric f/number) the diameter of the cone of light will large at the lens. As these rays travel towards the CCD they are converging. At the point were the cone of light intersects the cover glass it continues to have a large in diameter. Stated another way, at large apertures the dust spot cannot completely eclipse the cone of light. Thus the impact of a dust spot is minimized. Should the lens be operating at a tiny aperture, the cone of light originates from the lens with a tiny diameter. As it travels towards the CCD it converges at an acute angle. At the point where the cone of light transverse the cover glass, the dust spot and the cone of light will be nearly the same size. Thus at tiny apertures (large numeric f/number) the effect of the dust spot is maximized. Conclusion: Alan Marcus
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Karim Abiali |
Jonathan, I recommend you take the camear to Nikon or ship it to them. They will do clean for free the sensor for you. Avoid as much as you can to clean the sensor yourself. When changing lenses, hold the camera downward and do it as fast as you can. You should do this in a closed area and never outdoors. You can also buy a dust blower (rocket) to help you blow the dust. ka.
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Alan N. Marcus |
Jonathan, Sensor clearing is a fact of life for those who choose digital with interchangeable lenses. If you elect not to clean the sensor cover yourself, I advise running out and purchasing two more cameras of the same make and model. That way you can have one in use, one in transit, and one on the shelf on ready alert. Otherwise, follow this link for cleaning instructions. Alan Marcus www.luminous-landscape.com/essays/sensor-cleaning.shtml
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- Dennis Flanagan Contact Dennis Flanagan Dennis Flanagan's Gallery |
www.visibledust.com
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Alan N. Marcus |
A tip of the hat to Dennis from Alan Marcus
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Todd Bennett |
Jonathan, You might want to look at this too. I just recieved their kit in the mail and I am going to try it over the weekend. They guy has some good tutorials on how to do this.
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Jonathan Sabo |
I appreciate the overwhelming response, from what is probably a very common issue, that is out there. Yesterday I bought cleaning solution and a swab type of thing. (i forget the name,.. it honestly is meant for cleaning the sensors) and cleaned my sensor. Picture looks good, spot is gone. I just can't understand how a stick with some sort of non-lint crap goes for 45 dollars... oh well, it did the job, and I have my camera for the weekend. I'm happy. Once again, I appreciate it everyone.
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Kerry Drager |
Hi Jonathan, Welcome to the world of digital SLRs, and glad it's now worked out for you! Kerry
Pro Tips 1: How to Keep Your Digital Sensor Clean Pro Tips 2: How to Clean Your DSLR's Sensor
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Ariel Lepor |
And even if you only notice the spot after taking an important picture, chances are that you can make the spot disappear with proper image editing. Cloning (or a specialization thereof) specifically.
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Ariel Lepor |
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Jonathan Sabo |
I appreciate your attempt to help, however photoshopping every photo I take would be an extremely tedious task and is overall avoiding the issue at hand.
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Ariel Lepor |
Of course you want pictures that are good to start with, and you always want to make sure the sensor doesn't have dust on it. I was just pointing out that dust on a photo is not the end of the world.
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