Another weird artifact

Discussion in 'Digital Photography' started by 223rem, Feb 2, 2006.

  1. 223rem

    223rem Guest

    223rem, Feb 2, 2006
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  2. 223rem

    secheese Guest

    Probably still lens flare, but that one would concern me a bit more
    than your previous examples.
    secheese, Feb 2, 2006
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  3. It's the reflection off of the filter you have on the lens front and/or it's
    the lens elements themselves. If you center the moon dead center in the
    viewfinder this will go away.

    Rita Ä Berkowitz, Feb 2, 2006
  4. 223rem

    223rem Guest

    And that's because it reveals a lens defect? Well, it is a 70 dollar lens.
    223rem, Feb 2, 2006
  5. 223rem

    Ray Fischer Guest

    One effect of that lens is that light can reflect off of the sensor,
    be trasmitted forward through the lens, reflect off of the UV filter,
    and then back to the sensor. I've seen it happen a lot when I forget
    to take off the (admittedly cheap) UV filter I have on the lens.

    Take off the filter or get a good multi-coated filter.
    Ray Fischer, Feb 3, 2006
  6. That *is* lens flare, specifically unwanted reflections of the
    overexposed moon from element surfaces in the lens.

    Your previous images, with the spikes, showed diffraction from the iris
    leaf edges not, as others called it, flare.

    Diffraction is just another mechanism for bending light, which normally
    travels in a straight line. The lens bends the light, usually by
    refraction, to bring the image to a focus. However a certain amount of
    diffraction occurs at edges and even more when two edged get close
    together. Some of the light passing an edge, such as the iris, bends
    into the areas that would otherwise be obscured by the iris - the rest
    of the lens simply focusses that pattern onto the focal plane along with
    the main image. If you count the iris blades, you will find there are
    the same number of blades as there are spikes around the moon. If you
    opened the lens up, as you did on this shot above, the spikes disappear
    and become a general circular haze, because now the defining edges are
    the circular perimeters of the lens, not the iris.
    Kennedy McEwen, Feb 4, 2006
  7. 223rem

    223rem Guest

    Thanks, great explanation.
    223rem, Feb 5, 2006
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