Circular Light Areas in Photo

Discussion in 'Digital Photography' started by Steven Feinstein, Jul 1, 2005.

  1. I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    I take a photo and I get small circular areas which are lighter than the
    rest of the area. They remind me of what would happen when painting
    watercolors and an area blooms (but it is a perfect circle).

    It seems to happen when the flash fires but the subject is too far away
    or there are small areas of other sources of light. It also appears to
    be worse at 400 ISO.

    I'm trying to figure out what is happening in order to avoid the
    situation. If I had to make a guess, I'm thinking the shutter speed is
    fast (because the flash is firing), but the flash is not bouncing off a
    close object so the camera is picking up the light from the flash. Or
    if there is a window maybe it is picking up some outfoor light peaking in.

    Has anyone else seen this? Does what I suggest sound plausible?

    Looking for some advice on the cause.

    Thanks,

    Steve
    Steven Feinstein, Jul 1, 2005
    #1
    1. Advertising

  2. Steven Feinstein

    Frank ess Guest

    Steven Feinstein wrote:
    > I have a Canon A95. Occassionally (and I'm trying to narrow down
    > when) I take a photo and I get small circular areas which are
    > lighter than
    > the rest of the area. They remind me of what would happen when
    > painting watercolors and an area blooms (but it is a perfect
    > circle).
    >
    > It seems to happen when the flash fires but the subject is too far
    > away or there are small areas of other sources of light. It also
    > appears to be worse at 400 ISO.
    >
    > I'm trying to figure out what is happening in order to avoid the
    > situation. If I had to make a guess, I'm thinking the shutter speed
    > is fast (because the flash is firing), but the flash is not bouncing
    > off a close object so the camera is picking up the light from the
    > flash. Or if there is a window maybe it is picking up some outfoor
    > light
    > peaking in.
    > Has anyone else seen this? Does what I suggest sound plausible?
    >
    > Looking for some advice on the cause.
    >

    It's a mote in the middle distance.

    --
    Frank ess
    Frank ess, Jul 1, 2005
    #2
    1. Advertising

  3. Frank ess wrote:
    > Steven Feinstein wrote:
    >
    >> I have a Canon A95. Occassionally (and I'm trying to narrow down
    >> when) I take a photo and I get small circular areas which are lighter
    >> than
    >> the rest of the area. They remind me of what would happen when
    >> painting watercolors and an area blooms (but it is a perfect circle).
    >>
    >> It seems to happen when the flash fires but the subject is too far
    >> away or there are small areas of other sources of light. It also
    >> appears to be worse at 400 ISO.
    >>
    >> I'm trying to figure out what is happening in order to avoid the
    >> situation. If I had to make a guess, I'm thinking the shutter speed
    >> is fast (because the flash is firing), but the flash is not bouncing
    >> off a close object so the camera is picking up the light from the
    >> flash. Or if there is a window maybe it is picking up some outfoor light
    >> peaking in.
    >> Has anyone else seen this? Does what I suggest sound plausible?
    >>
    >> Looking for some advice on the cause.
    >>

    > It's a mote in the middle distance.
    >

    Are you saying that the flash is reflecting off of dust? This may be
    possible since the last batch were pictures of a person riding a horse
    in an indoor arena (on dirt), but the light areas seem pretty big for
    dust. As an example, one of the areas I'm looking at is about 1/6th the
    height of the picture. Would a reflection off of dust look that large?

    Also, if it is a mote, am I limited to not using the flash in dusty areas?

    Thanks for your response.
    Steven Feinstein, Jul 1, 2005
    #3
  4. Steven Feinstein wrote:
    > Frank ess wrote:
    >> Steven Feinstein wrote:
    >>
    >>> I have a Canon A95. Occassionally (and I'm trying to narrow down
    >>> when) I take a photo and I get small circular areas which are
    >>> lighter than
    >>> the rest of the area. They remind me of what would happen when
    >>> painting watercolors and an area blooms (but it is a perfect
    >>> circle). It seems to happen when the flash fires but the subject is
    >>> too far
    >>> away or there are small areas of other sources of light. It also
    >>> appears to be worse at 400 ISO.
    >>>
    >>> I'm trying to figure out what is happening in order to avoid the
    >>> situation. If I had to make a guess, I'm thinking the shutter speed
    >>> is fast (because the flash is firing), but the flash is not bouncing
    >>> off a close object so the camera is picking up the light from the
    >>> flash. Or if there is a window maybe it is picking up some outfoor
    >>> light peaking in.
    >>> Has anyone else seen this? Does what I suggest sound plausible?
    >>>
    >>> Looking for some advice on the cause.
    >>>

    >> It's a mote in the middle distance.
    >>

    > Are you saying that the flash is reflecting off of dust? This may be
    > possible since the last batch were pictures of a person riding a horse
    > in an indoor arena (on dirt), but the light areas seem pretty big for
    > dust. As an example, one of the areas I'm looking at is about 1/6th
    > the height of the picture. Would a reflection off of dust look that
    > large?
    > Also, if it is a mote, am I limited to not using the flash in dusty
    > areas?
    > Thanks for your response.


    It's worse in compact digital cameras because (1) the depth of field is
    much greater so that things which would be completely out of focus on
    large cameras can be in focus on compact ones (because of the much smaller
    sensor and shorter focal length lens) and (2) the axial separation between
    flash and lens is less.

    Either post-process the image, reduce the dust, or take several pictures
    and hope that one is OK.

    David
    David J Taylor, Jul 1, 2005
    #4
  5. Steven Feinstein

    Ron Hunter Guest

    Steven Feinstein wrote:
    > I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    > I take a photo and I get small circular areas which are lighter than the
    > rest of the area. They remind me of what would happen when painting
    > watercolors and an area blooms (but it is a perfect circle).
    >
    > It seems to happen when the flash fires but the subject is too far away
    > or there are small areas of other sources of light. It also appears to
    > be worse at 400 ISO.
    >
    > I'm trying to figure out what is happening in order to avoid the
    > situation. If I had to make a guess, I'm thinking the shutter speed is
    > fast (because the flash is firing), but the flash is not bouncing off a
    > close object so the camera is picking up the light from the flash. Or
    > if there is a window maybe it is picking up some outfoor light peaking in.
    >
    > Has anyone else seen this? Does what I suggest sound plausible?
    >
    > Looking for some advice on the cause.
    >
    > Thanks,
    >
    > Steve

    Yes. Usually when using flash, in a place where there is dust in the
    air. The dust particles will reflect the flash causing this problem.


    --
    Ron Hunter
    Ron Hunter, Jul 1, 2005
    #5
  6. Steven Feinstein

    Scott W Guest

    Steven Feinstein wrote:
    > I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    > I take a photo and I get small circular areas which are lighter than the
    > rest of the area. They remind me of what would happen when painting
    > watercolors and an area blooms (but it is a perfect circle).
    >
    > It seems to happen when the flash fires but the subject is too far away
    > or there are small areas of other sources of light. It also appears to
    > be worse at 400 ISO.
    >
    > I'm trying to figure out what is happening in order to avoid the
    > situation. If I had to make a guess, I'm thinking the shutter speed is
    > fast (because the flash is firing), but the flash is not bouncing off a
    > close object so the camera is picking up the light from the flash. Or
    > if there is a window maybe it is picking up some outfoor light peaking in.
    >
    > Has anyone else seen this? Does what I suggest sound plausible?
    >
    > Looking for some advice on the cause.
    >
    > Thanks,
    >
    > Steve


    It would help if we could see one of these photos.
    You might try aiming the camera straight up on a clear night and taking
    a flash photo.

    Scott
    Scott W, Jul 1, 2005
    #6
  7. Scott W wrote:
    > Steven Feinstein wrote:
    >
    >>I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    >>I take a photo and I get small circular areas which are lighter than the
    >>rest of the area. They remind me of what would happen when painting
    >>watercolors and an area blooms (but it is a perfect circle).
    >>
    >>It seems to happen when the flash fires but the subject is too far away
    >>or there are small areas of other sources of light. It also appears to
    >>be worse at 400 ISO.
    >>
    >>I'm trying to figure out what is happening in order to avoid the
    >>situation. If I had to make a guess, I'm thinking the shutter speed is
    >>fast (because the flash is firing), but the flash is not bouncing off a
    >>close object so the camera is picking up the light from the flash. Or
    >>if there is a window maybe it is picking up some outfoor light peaking in.
    >>
    >>Has anyone else seen this? Does what I suggest sound plausible?
    >>
    >>Looking for some advice on the cause.
    >>
    >>Thanks,
    >>
    >>Steve

    >
    >
    > It would help if we could see one of these photos.
    > You might try aiming the camera straight up on a clear night and taking
    > a flash photo.
    >
    > Scott
    >

    I uploaded three images as examples. Dust does seem to make sense, it's
    just that we took pictures at the same locations in a previous year
    using a point and shoot film camera and did not have this problem. Does
    it sound more like chance or is digital more sensitive to the dust?

    Light areas are:
    lapel of man
    knee of boy
    above white banner
    http://members.cox.net/sfein/images/img_1300.jpg

    Light areas are:
    at bottom
    on right near door
    http://members.cox.net/sfein/images/img_1258.jpg

    Light areas are all over the place:
    http://members.cox.net/sfein/images/img_1254.jpg

    I appreciate all the help from everyone.
    Steven Feinstein, Jul 1, 2005
    #7
  8. Steven Feinstein wrote:
    []
    > I uploaded three images as examples. Dust does seem to make sense,
    > it's just that we took pictures at the same locations in a previous
    > year using a point and shoot film camera and did not have this
    > problem. Does it sound more like chance or is digital more sensitive
    > to the dust?


    Yes. I already explained that to you - please re-read my post.

    David
    David J Taylor, Jul 1, 2005
    #8
  9. Steven Feinstein

    Bill Funk Guest

    On Fri, 01 Jul 2005 13:31:28 -0400, Steven Feinstein
    <> wrote:

    >Frank ess wrote:
    >> Steven Feinstein wrote:
    >>
    >>> I have a Canon A95. Occassionally (and I'm trying to narrow down
    >>> when) I take a photo and I get small circular areas which are lighter
    >>> than
    >>> the rest of the area. They remind me of what would happen when
    >>> painting watercolors and an area blooms (but it is a perfect circle).
    >>>
    >>> It seems to happen when the flash fires but the subject is too far
    >>> away or there are small areas of other sources of light. It also
    >>> appears to be worse at 400 ISO.
    >>>
    >>> I'm trying to figure out what is happening in order to avoid the
    >>> situation. If I had to make a guess, I'm thinking the shutter speed
    >>> is fast (because the flash is firing), but the flash is not bouncing
    >>> off a close object so the camera is picking up the light from the
    >>> flash. Or if there is a window maybe it is picking up some outfoor light
    >>> peaking in.
    >>> Has anyone else seen this? Does what I suggest sound plausible?
    >>>
    >>> Looking for some advice on the cause.
    >>>

    >> It's a mote in the middle distance.
    >>

    >Are you saying that the flash is reflecting off of dust? This may be
    >possible since the last batch were pictures of a person riding a horse
    >in an indoor arena (on dirt), but the light areas seem pretty big for
    >dust. As an example, one of the areas I'm looking at is about 1/6th the
    >height of the picture. Would a reflection off of dust look that large?
    >
    >Also, if it is a mote, am I limited to not using the flash in dusty areas?
    >
    >Thanks for your response.


    One-sixth of the picture is an awfully large dust mote!
    It would be great if you could post a link to a copy of a pic that
    shows this, then we would have a much better idea of what you mean.

    --
    Bill Funk
    replace "g" with "a"
    Bill Funk, Jul 1, 2005
    #9
  10. Steven Feinstein

    Owamanga Guest

    On Fri, 01 Jul 2005 15:22:23 -0400, Steven Feinstein
    <> wrote:

    >I uploaded three images as examples. Dust does seem to make sense, it's
    >just that we took pictures at the same locations in a previous year
    >using a point and shoot film camera and did not have this problem. Does
    >it sound more like chance or is digital more sensitive to the dust?
    >
    >http://members.cox.net/sfein/images/img_1300.jpg
    >http://members.cox.net/sfein/images/img_1258.jpg
    >http://members.cox.net/sfein/images/img_1254.jpg


    Wow, I've never seen that before.

    You can rule out dust on the surface of the lens / front filter by
    taking a couple of photos in quick succession with AF switched off (to
    prevent any possible front-element rotation) but framed slightly
    differently. However, I'm not sure how this would get illuminated by
    the flash.

    So, the only other plausible idea is as others have suggested - dust
    floating around in the air, quite close to the front element being
    illuminated by the flash - not much you can do about that...

    --
    Owamanga!
    http://www.pbase.com/owamanga
    Owamanga, Jul 1, 2005
    #10
  11. Steven Feinstein

    Scott W Guest

    Steven Feinstein wrote:
    > Scott W wrote:
    > > Steven Feinstein wrote:
    > >
    > >>I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    > >>I take a photo and I get small circular areas which are lighter than the
    > >>rest of the area. They remind me of what would happen when painting
    > >>watercolors and an area blooms (but it is a perfect circle).
    > >>
    > >>It seems to happen when the flash fires but the subject is too far away
    > >>or there are small areas of other sources of light. It also appears to
    > >>be worse at 400 ISO.
    > >>
    > >>I'm trying to figure out what is happening in order to avoid the
    > >>situation. If I had to make a guess, I'm thinking the shutter speed is
    > >>fast (because the flash is firing), but the flash is not bouncing off a
    > >>close object so the camera is picking up the light from the flash. Or
    > >>if there is a window maybe it is picking up some outfoor light peaking in.
    > >>
    > >>Has anyone else seen this? Does what I suggest sound plausible?
    > >>
    > >>Looking for some advice on the cause.
    > >>
    > >>Thanks,
    > >>
    > >>Steve

    > >
    > >
    > > It would help if we could see one of these photos.
    > > You might try aiming the camera straight up on a clear night and taking
    > > a flash photo.
    > >
    > > Scott
    > >

    > I uploaded three images as examples. Dust does seem to make sense, it's
    > just that we took pictures at the same locations in a previous year
    > using a point and shoot film camera and did not have this problem. Does
    > it sound more like chance or is digital more sensitive to the dust?
    >
    > Light areas are:
    > lapel of man
    > knee of boy
    > above white banner
    > http://members.cox.net/sfein/images/img_1300.jpg
    >
    > Light areas are:
    > at bottom
    > on right near door
    > http://members.cox.net/sfein/images/img_1258.jpg
    >
    > Light areas are all over the place:
    > http://members.cox.net/sfein/images/img_1254.jpg
    >
    > I appreciate all the help from everyone.


    It does look like dust, but I am surprised at how much you are getting.
    We have a very small digital camera that we use from time to time, I
    looked at several hundred flash photos from it and did not see dust in
    any of them. I have found two photos that show just a bit of dust in
    the air from my F828, but these were both taken in a wood shop where
    the saw had been used just a bit before, and even then I only saw a
    couple of spots.

    To see two in the same shot indoors to me seems very odd, others may
    have other experiences then what I have had.

    Scott
    Scott W, Jul 1, 2005
    #11
  12. Steven Feinstein wrote:
    > Scott W wrote:
    >
    >> Steven Feinstein wrote:
    >>
    >>> I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    >>> I take a photo and I get small circular areas which are lighter than the
    >>> rest of the area. They remind me of what would happen when painting
    >>> watercolors and an area blooms (but it is a perfect circle).
    >>>
    >>> It seems to happen when the flash fires but the subject is too far away
    >>> or there are small areas of other sources of light. It also appears to
    >>> be worse at 400 ISO.
    >>>
    >>> I'm trying to figure out what is happening in order to avoid the
    >>> situation. If I had to make a guess, I'm thinking the shutter speed is
    >>> fast (because the flash is firing), but the flash is not bouncing off a
    >>> close object so the camera is picking up the light from the flash. Or
    >>> if there is a window maybe it is picking up some outfoor light
    >>> peaking in.
    >>>
    >>> Has anyone else seen this? Does what I suggest sound plausible?
    >>>
    >>> Looking for some advice on the cause.
    >>>
    >>> Thanks,
    >>>
    >>> Steve

    >>
    >>
    >>
    >> It would help if we could see one of these photos.
    >> You might try aiming the camera straight up on a clear night and taking
    >> a flash photo.
    >>
    >> Scott
    >>

    > I uploaded three images as examples. Dust does seem to make sense, it's
    > just that we took pictures at the same locations in a previous year
    > using a point and shoot film camera and did not have this problem. Does
    > it sound more like chance or is digital more sensitive to the dust?
    >
    > Light areas are:
    > lapel of man
    > knee of boy
    > above white banner
    > http://members.cox.net/sfein/images/img_1300.jpg
    >
    > Light areas are:
    > at bottom
    > on right near door
    > http://members.cox.net/sfein/images/img_1258.jpg
    >
    > Light areas are all over the place:
    > http://members.cox.net/sfein/images/img_1254.jpg
    >
    > I appreciate all the help from everyone.

    Hi,

    I noticed the same type of light circles, only with flash from a great
    distance where the pictures were grossly underexposed, and were
    presumably shot at ISO 400 (automatic) in my Canon S-500. I assumed that
    it was a kind of digital "noise", and can't imagine why ISO 400 shows up
    dust more than ISO 100.

    Morton
    Morton Linder, Jul 1, 2005
    #12
  13. David J Taylor wrote:
    > Steven Feinstein wrote:
    > []
    >
    >>I uploaded three images as examples. Dust does seem to make sense,
    >>it's just that we took pictures at the same locations in a previous
    >>year using a point and shoot film camera and did not have this
    >>problem. Does it sound more like chance or is digital more sensitive
    >>to the dust?

    >
    >
    > Yes. I already explained that to you - please re-read my post.
    >
    > David
    >
    >

    Sorry David, I misinterpreted your message. I thought when you were
    comparing compact digital to larger cameras you meant larger digital
    cameras (i.e. DSLRs or even higher-end fixed lens). I did not think you
    meant vs film. So just to be sure, your description holds true for
    compact film cameras as well. The depth of filed is greater for compact
    digital vs compact film and most likely the flash is closer to the lens
    (which is true of my cameras).

    Thanks,

    Steve
    Steven Feinstein, Jul 1, 2005
    #13
  14. Bill Funk wrote:
    > On Fri, 01 Jul 2005 13:31:28 -0400, Steven Feinstein
    > <> wrote:
    >
    >
    >>Frank ess wrote:
    >>
    >>>Steven Feinstein wrote:
    >>>
    >>>
    >>>>I have a Canon A95. Occassionally (and I'm trying to narrow down
    >>>>when) I take a photo and I get small circular areas which are lighter
    >>>>than
    >>>>the rest of the area. They remind me of what would happen when
    >>>>painting watercolors and an area blooms (but it is a perfect circle).
    >>>>
    >>>>It seems to happen when the flash fires but the subject is too far
    >>>>away or there are small areas of other sources of light. It also
    >>>>appears to be worse at 400 ISO.
    >>>>
    >>>>I'm trying to figure out what is happening in order to avoid the
    >>>>situation. If I had to make a guess, I'm thinking the shutter speed
    >>>>is fast (because the flash is firing), but the flash is not bouncing
    >>>>off a close object so the camera is picking up the light from the
    >>>>flash. Or if there is a window maybe it is picking up some outfoor light
    >>>>peaking in.
    >>>>Has anyone else seen this? Does what I suggest sound plausible?
    >>>>
    >>>>Looking for some advice on the cause.
    >>>>
    >>>
    >>>It's a mote in the middle distance.
    >>>

    >>
    >>Are you saying that the flash is reflecting off of dust? This may be
    >>possible since the last batch were pictures of a person riding a horse
    >>in an indoor arena (on dirt), but the light areas seem pretty big for
    >>dust. As an example, one of the areas I'm looking at is about 1/6th the
    >>height of the picture. Would a reflection off of dust look that large?
    >>
    >>Also, if it is a mote, am I limited to not using the flash in dusty areas?
    >>
    >>Thanks for your response.

    >
    >
    > One-sixth of the picture is an awfully large dust mote!
    > It would be great if you could post a link to a copy of a pic that
    > shows this, then we would have a much better idea of what you mean.
    >

    Well it's 1/6th the height, not 1/6th the entire image. But still
    pretty large.
    Steven Feinstein, Jul 1, 2005
    #14
  15. Owamanga wrote:
    > On Fri, 01 Jul 2005 15:22:23 -0400, Steven Feinstein
    > <> wrote:
    >
    >
    >>I uploaded three images as examples. Dust does seem to make sense, it's
    >>just that we took pictures at the same locations in a previous year
    >>using a point and shoot film camera and did not have this problem. Does
    >>it sound more like chance or is digital more sensitive to the dust?
    >>
    >>http://members.cox.net/sfein/images/img_1300.jpg
    >>http://members.cox.net/sfein/images/img_1258.jpg
    >>http://members.cox.net/sfein/images/img_1254.jpg

    >
    >
    > Wow, I've never seen that before.
    >
    > You can rule out dust on the surface of the lens / front filter by
    > taking a couple of photos in quick succession with AF switched off (to
    > prevent any possible front-element rotation) but framed slightly
    > differently. However, I'm not sure how this would get illuminated by
    > the flash.
    >
    > So, the only other plausible idea is as others have suggested - dust
    > floating around in the air, quite close to the front element being
    > illuminated by the flash - not much you can do about that...
    >
    > --
    > Owamanga!
    > http://www.pbase.com/owamanga

    I do have other pictures from the same day where I don't see the circles
    so I don't think it is dust on the lens (though I will clean it). The
    picture of the 4 people standing was done on a different day and I was
    hoping it was a one-time thing. Now I'm going to have to check for
    focus and dust reflections when I review an image.
    Steven Feinstein, Jul 1, 2005
    #15
  16. Morton Linder wrote:
    > Steven Feinstein wrote:
    >
    >> Scott W wrote:
    >>
    >>> Steven Feinstein wrote:
    >>>
    >>>> I have a Canon A95. Occassionally (and I'm trying to narrow down when)
    >>>> I take a photo and I get small circular areas which are lighter than
    >>>> the
    >>>> rest of the area. They remind me of what would happen when painting
    >>>> watercolors and an area blooms (but it is a perfect circle).
    >>>>
    >>>> It seems to happen when the flash fires but the subject is too far away
    >>>> or there are small areas of other sources of light. It also appears to
    >>>> be worse at 400 ISO.
    >>>>
    >>>> I'm trying to figure out what is happening in order to avoid the
    >>>> situation. If I had to make a guess, I'm thinking the shutter speed is
    >>>> fast (because the flash is firing), but the flash is not bouncing off a
    >>>> close object so the camera is picking up the light from the flash. Or
    >>>> if there is a window maybe it is picking up some outfoor light
    >>>> peaking in.
    >>>>
    >>>> Has anyone else seen this? Does what I suggest sound plausible?
    >>>>
    >>>> Looking for some advice on the cause.
    >>>>
    >>>> Thanks,
    >>>>
    >>>> Steve
    >>>
    >>>
    >>>
    >>>
    >>> It would help if we could see one of these photos.
    >>> You might try aiming the camera straight up on a clear night and taking
    >>> a flash photo.
    >>>
    >>> Scott
    >>>

    >> I uploaded three images as examples. Dust does seem to make sense,
    >> it's just that we took pictures at the same locations in a previous
    >> year using a point and shoot film camera and did not have this
    >> problem. Does it sound more like chance or is digital more sensitive
    >> to the dust?
    >>
    >> Light areas are:
    >> lapel of man
    >> knee of boy
    >> above white banner
    >> http://members.cox.net/sfein/images/img_1300.jpg
    >>
    >> Light areas are:
    >> at bottom
    >> on right near door
    >> http://members.cox.net/sfein/images/img_1258.jpg
    >>
    >> Light areas are all over the place:
    >> http://members.cox.net/sfein/images/img_1254.jpg
    >>
    >> I appreciate all the help from everyone.

    >
    > Hi,
    >
    > I noticed the same type of light circles, only with flash from a great
    > distance where the pictures were grossly underexposed, and were
    > presumably shot at ISO 400 (automatic) in my Canon S-500. I assumed that
    > it was a kind of digital "noise", and can't imagine why ISO 400 shows up
    > dust more than ISO 100.
    >
    > Morton

    The worse ones were shot in action mode which shows as automatic in the
    EXIF, but it's most likely shot at 400. The picture of the 4 people was
    shot at 50 so I'm surprised that one had the issue (maybe dust shows up
    more on black - which was the color of the suits).

    Steve
    Steven Feinstein, Jul 1, 2005
    #16
  17. Steven Feinstein

    Belgos Guest

    "David J Taylor"
    <-this-bit.nor-this-part.uk.invalid> wrote in
    message news:wNgxe.60413$...
    > Steven Feinstein wrote:
    > []
    > > I uploaded three images as examples. Dust does seem to make sense,
    > > it's just that we took pictures at the same locations in a previous
    > > year using a point and shoot film camera and did not have this
    > > problem. Does it sound more like chance or is digital more sensitive
    > > to the dust?

    >
    > Yes. I already explained that to you - please re-read my post.


    I don't think that smaller DOF would help a lot with this - in any case the
    light circles are way out of focus.

    But anyway, I had the same on my A300. Some shots where ruined this way, and
    mine were even worse, as you didn't need any coordinates to help somebody
    locate them :)
    I think it's better to do what somebody else suggested, take many frames and
    hope some are clean, as to reduce the dust from the air is, ehm, a bit
    difficult :)

    Kostas
    Belgos, Jul 1, 2005
    #17
  18. Steven Feinstein

    Larry Guest

    In article <U5fxe.22219$FP2.20527@lakeread03>,
    says...
    > >

    > Are you saying that the flash is reflecting off of dust? This may be
    > possible since the last batch were pictures of a person riding a horse
    > in an indoor arena (on dirt), but the light areas seem pretty big for
    > dust. As an example, one of the areas I'm looking at is about 1/6th the
    > height of the picture. Would a reflection off of dust look that large?
    >
    > Also, if it is a mote, am I limited to not using the flash in dusty areas?
    >
    > Thanks for your response.
    >


    Its a"built in" limitation of using the in camera flash which is VERY close
    to the lens.

    It happens for the same reason that you are more likely to get "RED EYE" in a
    picture with the in camera flash.

    In a dusty atmosphere a very small dust mote can appear as a HUGE bright,
    globelike bright spot.


    --
    Larry Lynch
    Mystic, Ct.
    Larry, Jul 1, 2005
    #18
  19. Steven Feinstein

    Guest

    In message <U5fxe.22219$FP2.20527@lakeread03>,
    Steven Feinstein <> wrote:

    >Also, if it is a mote, am I limited to not using the flash in dusty areas?


    That kind of flash, yes. It is very close to the lens, so any dust that
    is close to both will be many stops brighter than the subject.

    If you had a separate flash, it could be used far from the camera
    (higher, besides, or behind) so that no dust will be much closer to the
    flash than the subject, and be visible in the capture at the same time.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
    , Jul 1, 2005
    #19
  20. Steven Feinstein

    Chips Guest

    I get that all the time when taking pictures on a construction site.

    There can be dust in the air, and you can't even see it.

    But the flash fires, and it shows them all over the picture.

    Maybe you could use this phenomenon to check for dusty air.

    Greg Chapp


    "Steven Feinstein" <> wrote in message
    news:U5fxe.22219$FP2.20527@lakeread03...
    > Frank ess wrote:
    >> Steven Feinstein wrote:
    >>
    >>> I have a Canon A95. Occassionally (and I'm trying to narrow down
    >>> when) I take a photo and I get small circular areas which are lighter
    >>> than
    >>> the rest of the area. They remind me of what would happen when
    >>> painting watercolors and an area blooms (but it is a perfect circle).
    >>>
    >>> It seems to happen when the flash fires but the subject is too far
    >>> away or there are small areas of other sources of light. It also
    >>> appears to be worse at 400 ISO.
    >>>
    >>> I'm trying to figure out what is happening in order to avoid the
    >>> situation. If I had to make a guess, I'm thinking the shutter speed
    >>> is fast (because the flash is firing), but the flash is not bouncing
    >>> off a close object so the camera is picking up the light from the
    >>> flash. Or if there is a window maybe it is picking up some outfoor
    >>> light
    >>> peaking in.
    >>> Has anyone else seen this? Does what I suggest sound plausible?
    >>>
    >>> Looking for some advice on the cause.
    >>>

    >> It's a mote in the middle distance.
    >>

    > Are you saying that the flash is reflecting off of dust? This may be
    > possible since the last batch were pictures of a person riding a horse in
    > an indoor arena (on dirt), but the light areas seem pretty big for dust.
    > As an example, one of the areas I'm looking at is about 1/6th the height
    > of the picture. Would a reflection off of dust look that large?
    >
    > Also, if it is a mote, am I limited to not using the flash in dusty areas?
    >
    > Thanks for your response.
    Chips, Jul 1, 2005
    #20
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Claude Balls

    Circular images

    Claude Balls, Sep 7, 2003, in forum: Computer Support
    Replies:
    22
    Views:
    8,854
    Patrick
    Sep 9, 2003
  2. ishtarbgl
    Replies:
    0
    Views:
    517
    ishtarbgl
    Apr 1, 2004
  3. Replies:
    5
    Views:
    4,290
    irwell
    Mar 13, 2008
  4. fill light source size vs main light size

    , Dec 11, 2008, in forum: Digital Photography
    Replies:
    10
    Views:
    899
    Dudley Hanks
    Dec 13, 2008
  5. Brian
    Replies:
    31
    Views:
    1,105
    Bob Larter
    Jun 14, 2009
Loading...

Share This Page