Strange Dots -- Help?

Discussion in 'Digital Photography' started by cjcampbell, Mar 22, 2006.

  1. cjcampbell

    cjcampbell Guest

    These two photos were taken just a few seconds apart. The first was
    taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.

    http://homepage.mac.com/christopherjcampbell/Problem Photos/

    I can understand the star filter effect might be caused by stopping
    down, but where did the dots come from?

    The lens used is the 12-24mm f/2.8 AF-S Nikkor. A tripod was used for
    both pictures, which are a night scene of Heritage Street in Vigan. No
    processing, color balancing, or sharpening was applied to both
    pictures. These are just JPGs taken straight from the original raw
    files.
    cjcampbell, Mar 22, 2006
    #1
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  2. cjcampbell

    John Guest

    "cjcampbell" <> wrote in message news:...
    > These two photos were taken just a few seconds apart. The first was
    > taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    >
    > http://homepage.mac.com/christopherjcampbell/Problem Photos/
    >
    > I can understand the star filter effect might be caused by stopping
    > down, but where did the dots come from?


    No idea, but are black people allowed in your church?
    John, Mar 22, 2006
    #2
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  3. cjcampbell

    cjcampbell Guest

    John wrote:
    > "cjcampbell" <> wrote in message news:...
    > > These two photos were taken just a few seconds apart. The first was
    > > taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    > >
    > > http://homepage.mac.com/christopherjcampbell/Problem Photos/
    > >
    > > I can understand the star filter effect might be caused by stopping
    > > down, but where did the dots come from?

    >
    > No idea, but are black people allowed in your church?


    Eh? Strange question, but yes, black people are allowed in our church.
    cjcampbell, Mar 22, 2006
    #3
  4. cjcampbell

    Steve Wolfe Guest

    "cjcampbell" <> wrote in message
    news:...
    > These two photos were taken just a few seconds apart. The first was
    > taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    >
    > http://homepage.mac.com/christopherjcampbell/Problem Photos/
    >
    > I can understand the star filter effect might be caused by stopping
    > down, but where did the dots come from?


    They appear to be out-of-focus highlights, or "orbs". My guess is that it
    was raining, snowing, or at least very humid. Something in the air
    refracted the light from the street lamp. You typically see this when a
    flash reflects off of dust, rain, or snow, but the same can occur via
    refraction as well.

    steve
    Steve Wolfe, Mar 22, 2006
    #4
  5. cjcampbell

    cjcampbell Guest

    Steve Wolfe wrote:
    > "cjcampbell" <> wrote in message
    > news:...
    > > These two photos were taken just a few seconds apart. The first was
    > > taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    > >
    > > http://homepage.mac.com/christopherjcampbell/Problem Photos/
    > >
    > > I can understand the star filter effect might be caused by stopping
    > > down, but where did the dots come from?

    >
    > They appear to be out-of-focus highlights, or "orbs". My guess is that it
    > was raining, snowing, or at least very humid. Something in the air
    > refracted the light from the street lamp. You typically see this when a
    > flash reflects off of dust, rain, or snow, but the same can occur via
    > refraction as well.


    Seems possible. It is very humid here all of the time, but I had not
    seen this before. Something that lends support to your idea is the haze
    around the lights in the first picture. It was not raining or snowing,
    though -- especially not the latter, this being the Philippines and
    very tropical. :)
    cjcampbell, Mar 22, 2006
    #5
  6. cjcampbell

    pltrgyst Guest

    On 21 Mar 2006 18:00:48 -0800, "cjcampbell" <>
    wrote:

    >These two photos were taken just a few seconds apart. The first was
    >taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    >
    >http://homepage.mac.com/christopherjcampbell/Problem Photos/
    >
    >I can understand the star filter effect might be caused by stopping
    >down, but where did the dots come from?
    >
    >.... These are just JPGs taken straight from the original raw
    >files.


    jpeg artifacts? Either that or micro-UFOs. That's my guess and I'm sticking with
    it.

    -- Larry
    pltrgyst, Mar 22, 2006
    #6
  7. cjcampbell

    cjcampbell Guest

    pltrgyst wrote:
    > On 21 Mar 2006 18:00:48 -0800, "cjcampbell" <>
    > wrote:
    >
    > >These two photos were taken just a few seconds apart. The first was
    > >taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    > >
    > >http://homepage.mac.com/christopherjcampbell/Problem Photos/
    > >
    > >I can understand the star filter effect might be caused by stopping
    > >down, but where did the dots come from?
    > >
    > >.... These are just JPGs taken straight from the original raw
    > >files.

    >
    > jpeg artifacts? Either that or micro-UFOs. That's my guess and I'm sticking with
    > it.


    Can't be jpeg artifacts. They show up on the raw files, too. According
    to Douglas Adams, the last invasion by micro-UFOs was swallowed by a
    small dog. You would think that they had learned their lesson. Unless
    they have returned in greater numbers...
    cjcampbell, Mar 22, 2006
    #7
  8. cjcampbell

    Guest

    A 12mm lens (was it set to that? -it *looks* like it's pretty wide..)
    shot at f22 will have a *lot* of depth of field. Those spots look very
    much like the effect you would get from (small) raindrops on a UV
    filter on the front of the lens, or they could conceivably even be on
    the front element.

    They don't look like orbs (ie lit up dust motes) to me, and they would
    have to be *very* close to the lens to be that far out of focus.
    Besides, in 5 seconds, rain or dust motes will move so far they would
    barely leave a trail.. These haven't.

    Muck on the lens or on a filter. betcha.

    ((Thinks - I guess they could even be on the sensor...but if he has let
    his sensor get that filthy, he needs his photography license revoked.))
    , Mar 22, 2006
    #8
  9. cjcampbell wrote:
    > These two photos were taken just a few seconds apart. The first was
    > taken at f/4 and 1/6 second; the other at f/22 and 5 seconds.
    >
    > http://homepage.mac.com/christopherjcampbell/Problem Photos/
    >
    > I can understand the star filter effect might be caused by stopping
    > down, but where did the dots come from?
    >
    > The lens used is the 12-24mm f/2.8 AF-S Nikkor. A tripod was used for
    > both pictures, which are a night scene of Heritage Street in Vigan. No
    > processing, color balancing, or sharpening was applied to both
    > pictures. These are just JPGs taken straight from the original raw
    > files.
    >

    Looks to me like the lens had a finger print or droplets on it
    or something. Stuff like that will come into focus as you stop
    down. I bet you could re-created the effect by taking a picture
    like that at a distant candle in the house with the lights off
    before and after smudging a filter in front of the lens.
    Just an Idea.

    Butch
    Butch Lacadie, Mar 22, 2006
    #9
  10. cjcampbell

    2 Guest

    It is dust on the lens (or if you are using a filter, it's on the filter).

    You came across the ideal situation for dust to show up: dark background,
    single point main light source, wide lens and tiny aperture (deep DOF).
    2, Mar 22, 2006
    #10
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