quality photos in florescent lighting

Discussion in 'Digital Photography' started by digi, Nov 4, 2007.

  1. digi

    digi Guest

    I have a Nikon Coolpix 7900 that is about 3 years old. I am
    considering replacing this camera with another point and shoot digital
    camera (not SLR), because the quality of the pictures I take in
    florescent lighting is poor. I have tried resetting the white balance
    feature and that didn't help. l would like a camera with a larger LCD
    display and a lithium battery. Does anyone have any suggestions for a
    camera that takes good pictures in poor/low lighting, and/or
    suggestions of how to take better pictures in poor/low lighting? I am
    tired of having to lighten so many pictures in Photoshop!
     
    digi, Nov 4, 2007
    #1
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  2. There are two problems. First there is not one florescent light color
    there are many. Second it the light is not continuous spectrum. That means
    while one camera or setting may work well in one situation, it likely will
    not work well in another. It is a moving target.

    I don't know if one or another CAMERA may offer better results, I
    suspect some will, but you may also need to do more post exposure
    processing and a RAW image would help there, but again I am not sure many or
    any point and shoot cameras offer that option.

    Of course you may already know all that.

    Good Luck

    "digi" <> wrote in message
    news:...
    > I have a Nikon Coolpix 7900 that is about 3 years old. I am
    > considering replacing this camera with another point and shoot digital
    > camera (not SLR), because the quality of the pictures I take in
    > florescent lighting is poor. I have tried resetting the white balance
    > feature and that didn't help. l would like a camera with a larger LCD
    > display and a lithium battery. Does anyone have any suggestions for a
    > camera that takes good pictures in poor/low lighting, and/or
    > suggestions of how to take better pictures in poor/low lighting? I am
    > tired of having to lighten so many pictures in Photoshop!
    >


    --
    Joseph Meehan

    Dia 's Muire duit
     
    Joseph Meehan, Nov 4, 2007
    #2
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  3. On Sat, 03 Nov 2007 18:15:28 -0700, digi wrote:

    > I have a Nikon Coolpix 7900 that is about 3 years old. I am considering
    > replacing this camera with another point and shoot digital camera (not
    > SLR), because the quality of the pictures I take in florescent lighting
    > is poor. I have tried resetting the white balance feature and that
    > didn't help. l would like a camera with a larger LCD display and a
    > lithium battery. Does anyone have any suggestions for a camera that
    > takes good pictures in poor/low lighting, and/or suggestions of how to
    > take better pictures in poor/low lighting? I am tired of having to
    > lighten so many pictures in Photoshop!


    First, pick a camera that permits you to set the exposure (f-stop and
    shutter) manually. Then bracket your exposures and pick the best one.

    Learn how to use fill flash and color compensation/correction filters
    over the flash to balance it to the ambient light.

    As to color balance, get a camera that has a Custom White Balance option,
    where you point the camera at a white target (I use general sheet of acid-
    free, drawing paper) under the light source you're shooting under and
    click the shutter. You're color balanced or, at least, color balanced to
    the best the camera can be. Tweak in Photoshop.

    Stef
     
    Stefan Patric, Nov 5, 2007
    #3
  4. "Stefan Patric" <> wrote in message
    news:mcwXi.873$...
    > On Sat, 03 Nov 2007 18:15:28 -0700, digi wrote:
    >
    >> I have a Nikon Coolpix 7900 that is about 3 years old. I am considering
    >> replacing this camera with another point and shoot digital camera (not
    >> SLR), because the quality of the pictures I take in florescent lighting
    >> is poor. I have tried resetting the white balance feature and that
    >> didn't help. l would like a camera with a larger LCD display and a
    >> lithium battery. Does anyone have any suggestions for a camera that
    >> takes good pictures in poor/low lighting, and/or suggestions of how to
    >> take better pictures in poor/low lighting? I am tired of having to
    >> lighten so many pictures in Photoshop!

    >
    > First, pick a camera that permits you to set the exposure (f-stop and
    > shutter) manually. Then bracket your exposures and pick the best one.


    I agree, exposure can play a surprisingly big part in this issue.

    >
    > Learn how to use fill flash and color compensation/correction filters
    > over the flash to balance it to the ambient light.


    As suggested the flash would need to be "corrected" to match whatever
    florescent light was in use. This could be next to impossible for a
    professional and likely impossible for the vast majority of us real people.

    >
    > As to color balance, get a camera that has a Custom White Balance option,
    > where you point the camera at a white target (I use general sheet of acid-
    > free, drawing paper) under the light source you're shooting under and
    > click the shutter. You're color balanced or, at least, color balanced to
    > the best the camera can be. Tweak in Photoshop.


    Yes that is about the best and only solution available. I would also
    suggest that different cameras have different abilities and some
    experimentation may prove helpful.

    Balancing florescent is a challenge for all photographers and and
    cameras as there are so many different "florescent" colors and they are
    "bright line" not continuous colors so they do some very strange things.

    >
    > Stef


    --
    Joseph Meehan

    Dia 's Muire duit
     
    Joseph Meehan, Nov 5, 2007
    #4
  5. digi

    Jamie Dalton Guest

    On Sat, 03 Nov 2007 18:15:28 -0700, digi <> wrote:

    >I have a Nikon Coolpix 7900 that is about 3 years old. I am
    >considering replacing this camera with another point and shoot digital
    >camera (not SLR), because the quality of the pictures I take in
    >florescent lighting is poor. I have tried resetting the white balance
    >feature and that didn't help. l would like a camera with a larger LCD
    >display and a lithium battery. Does anyone have any suggestions for a
    >camera that takes good pictures in poor/low lighting, and/or
    >suggestions of how to take better pictures in poor/low lighting? I am
    >tired of having to lighten so many pictures in Photoshop!


    Just out of curiosity, are you having to lighten all your photos in post
    processing or only certain ones? If it is all of them then you might need your
    monitor calibrated properly, or a better monitor. Your constant white-balance
    problem points to this as being the suspect in the crime too. Most cameras these
    days do a pretty decent job with their presets for fluorescent or auto
    white-balance options.

    If you are using a PC download this graphic for gamma 2.20 and view it on your
    screen

    http://www.aim-dtp.net/aim/download/monitor_gamma/220.png

    If all bands appear as even shades of gray with no obvious color shifts in them,
    then your monitor is doing okay for color balance. If you can see the black and
    gray squares in the top right band and only black (no gray squares) in the
    bottom right band, then your dark values are also set properly.

    If you are using a Mac, then download this one instead for a monitor gamma of
    1.70

    http://www.aim-dtp.net/aim/download/monitor_gamma/170.png


    View either one in your browser or graphic viewer at 100% resolution. If you use
    any resizing on it (enlarging or reducing) it does not work for testing your
    monitor's white-balance and gamma.

    If the image doesn't look right, color shifts in the gray bands, can't see the
    gray squares in the top-right black band, or you can see them in the lower-right
    black band, then adjust your monitor's colors, brightness, and contrast settings
    until all appears correct.

    If that's been the problem all along then, sadly, every photo you've edited all
    this time has been badly shifted in editing and needs to be redone.
     
    Jamie Dalton, Nov 5, 2007
    #5
  6. On Mon, 05 Nov 2007 05:52:22 -0500, Joseph Meehan wrote:

    > "Stefan Patric" <> wrote in message
    > news:mcwXi.873$...
    >> On Sat, 03 Nov 2007 18:15:28 -0700, digi wrote:
    >>
    >>> I have a Nikon Coolpix 7900 that is about 3 years old. I am
    >>> considering replacing this camera with another point and shoot digital
    >>> camera (not SLR), because the quality of the pictures I take in
    >>> florescent lighting is poor. I have tried resetting the white balance
    >>> feature and that didn't help.
    >>> [snip]

    >>
    >> Learn how to use fill flash and color compensation/correction filters
    >> over the flash to balance it to the ambient light.

    >
    > As suggested the flash would need to be "corrected" to match
    > whatever
    > florescent light was in use. This could be next to impossible for a
    > professional and likely impossible for the vast majority of us real
    > people.


    Not anywhere near next to impossible: Difficult, sometimes; fairly easy,
    most of the time. Did it for years, when all there was was film. With
    digital, it's a snap.

    >> As to color balance, get a camera that has a Custom White Balance
    >> option, where you point the camera at a white target (I use general
    >> sheet of acid- free, drawing paper) under the light source you're
    >> shooting under and click the shutter. You're color balanced or, at
    >> least, color balanced to the best the camera can be. Tweak in
    >> Photoshop.

    >
    > Yes that is about the best and only solution available. I would
    > also
    > suggest that different cameras have different abilities and some
    > experimentation may prove helpful.
    >
    > Balancing florescent is a challenge for all photographers and and
    > cameras as there are so many different "florescent" colors and they are
    > "bright line" not continuous colors so they do some very strange things.


    FWIW: 97% or so of all fluorescent tubes used in commercial and
    residential buildings are Cool Whites. A .30 to .35 Magenta filter over
    the camera lens with the camera color balance set to "Daylight" will get
    you within a few points of balanced 98% of the time. The other 2.9% of
    the tubes are Warm White Deluxe, which are almost dead-on 3200K color
    temperature. Set your camera to Tungsten. No filter needed. Tweak in
    post.

    To balance flash to Cool Whites, Rosco Industries' "Window Green" works
    great!

    In some industrial uses, and convention and exhibit halls, the artificial
    lighting is true daylight balanced. Usually no correction is need or at
    most, set the camera to "Electronic Flash" to warm things up a little.

    Check out Rosco's web site. They have just about any color correction,
    color alteration media you'll ever need. http://www.rosco.com/ Or
    almost as good is http://www.leefilters.com/

    Stef
     
    Stefan Patric, Nov 7, 2007
    #6
  7. On Wed, 07 Nov 2007 06:06:12 GMT, Stefan Patric <> wrote:

    >On Mon, 05 Nov 2007 05:52:22 -0500, Joseph Meehan wrote:
    >
    >> "Stefan Patric" <> wrote in message
    >> news:mcwXi.873$...
    >>> On Sat, 03 Nov 2007 18:15:28 -0700, digi wrote:
    >>>
    >>>> I have a Nikon Coolpix 7900 that is about 3 years old. I am
    >>>> considering replacing this camera with another point and shoot digital
    >>>> camera (not SLR), because the quality of the pictures I take in
    >>>> florescent lighting is poor. I have tried resetting the white balance
    >>>> feature and that didn't help.
    >>>> [snip]
    >>>
    >>> Learn how to use fill flash and color compensation/correction filters
    >>> over the flash to balance it to the ambient light.

    >>
    >> As suggested the flash would need to be "corrected" to match
    >> whatever
    >> florescent light was in use. This could be next to impossible for a
    >> professional and likely impossible for the vast majority of us real
    >> people.

    >
    >Not anywhere near next to impossible: Difficult, sometimes; fairly easy,
    >most of the time. Did it for years, when all there was was film. With
    >digital, it's a snap.
    >
    >>> As to color balance, get a camera that has a Custom White Balance
    >>> option, where you point the camera at a white target (I use general
    >>> sheet of acid- free, drawing paper) under the light source you're
    >>> shooting under and click the shutter. You're color balanced or, at
    >>> least, color balanced to the best the camera can be. Tweak in
    >>> Photoshop.

    >>
    >> Yes that is about the best and only solution available. I would
    >> also
    >> suggest that different cameras have different abilities and some
    >> experimentation may prove helpful.
    >>
    >> Balancing florescent is a challenge for all photographers and and
    >> cameras as there are so many different "florescent" colors and they are
    >> "bright line" not continuous colors so they do some very strange things.

    >
    >FWIW: 97% or so of all fluorescent tubes used in commercial and
    >residential buildings are Cool Whites. A .30 to .35 Magenta filter over
    >the camera lens with the camera color balance set to "Daylight" will get
    >you within a few points of balanced 98% of the time. The other 2.9% of
    >the tubes are Warm White Deluxe, which are almost dead-on 3200K color
    >temperature. Set your camera to Tungsten. No filter needed. Tweak in
    >post.
    >
    >To balance flash to Cool Whites, Rosco Industries' "Window Green" works
    >great!
    >
    >In some industrial uses, and convention and exhibit halls, the artificial
    >lighting is true daylight balanced. Usually no correction is need or at
    >most, set the camera to "Electronic Flash" to warm things up a little.
    >
    >Check out Rosco's web site. They have just about any color correction,
    >color alteration media you'll ever need. http://www.rosco.com/ Or
    >almost as good is http://www.leefilters.com/
    >
    >Stef


    Fluorescent lights and photography is not just as simple as trying to find the
    right filter or getting the right manual or preset white balance. Shutter speed
    will also have an effect on what color you are receiving from fluorescent
    lights. Not only do the phosphors from each type put out particular spectral
    lines, meaning there's no continuous spectrum to deal with and each and every
    type of sensor will see that light differently, but during the 60 (or 50) Hz
    cycle that powers most fluorescent lighting, those phosphors go through a
    drastic color shift each cycle. This is not true of many of the newer compact
    fluorescent lights that use a high frequency high-voltage to power them. But for
    your average, straight tubed, 60/50Hz ballast operated fluorescent's, then yes.

    This spectral color-shift is most often noticed when viewing a spinning fan
    blade under fluorescent lights. The light acting as a 60/50 Hz strobe will show
    blurry edges of those blades when they sync. If you look more closely you'll
    often see that the leading and trailing edges are also of two different colors.
    One edge strongly hued in reds or orange and the other in blues.

    The simplest way to observe this effect is by looking at any fluorescent light
    through the EVF of any decent P&S camera. As you crank up the shutter-speed the
    EVF will match what the shutter-speed is seeing. At certain speeds the
    fluorescent light will slowly grow brighter and dimmer continuously in the EVF.
    So dim in fact, that during part of its cycle it looks as if the fluorescent
    light isn't on at all.

    If you are fortunate enough to have a Canon P&S camera that is running CHDK,
    using CHDK's advanced RGB full color histograms, you can watch that histogram
    swing wildly through various cyclings of color shifts. First the blue histogram
    graph will be most prominent, then the red while the blue recedes, etc. To your
    eye it all seems as if blended into white. The camera with faster shutter-speeds
    will only pick up one brief moment during that 60/50 Hz spectral montage. At
    slower than 60th of a second shutter speeds you'll at least get 1 averaged
    white-cycle, but then only a portion of one of the hue-shifted cycles. So even
    using slower shutter speeds will have this problem.

    This is also why using manual white-balance may not always work. Unless the
    camera is using a shutter speed slower than 1/30th of a second to get an average
    sampling of two full cyclic shifts in colors, that white piece of paper you are
    using for your manual white-balance will be reflecting the same drastic color
    changes. If you only sample a portion of the full cycle of light intensity and
    colors your white balance will be off. You may have to sample several times
    before you are lucky enough to hit on an average section from the fluorescent
    light's kaleidoscope of colors.

    I knew of this color-shifting property of fluorescent lights from my childhood
    and when experimenting with the physics of light. When first testing the
    capability of the RGB blended histogram of a CHDK enabled camera I could think
    of no better test than seeing how it would show the changes in a fluorescent
    light. It showed it admirably. It's fun to watch it graphically display what I
    had only seen as a multi-colored strobe effect on fan blades until then. You
    just have to pick the right shutter speed to get it to sync and sample the
    fluorescent light to the best effect.

    Any of you that have a CHDK capable camera I urge you to look at any
    ballast-powered fluorescent light though it while having the blended RGB
    histogram active. (This won't work on compact fluorescents that I've tested so
    far, due to their high-frequency power source.) It's a fun science experiment
    and will show you why trying to white-balance for those lights can be a
    nightmare hit & miss lottery with every photo taken. Try a shutter speed of
    about 1/320th of a second, that seems to work well for displaying the best color
    shifts that occur, chopping them up fine enough to match the speed of the CCD
    and EVF display elements. But so do other shutter speeds. A CHDK equipped camera
    and the RGB histogram capability makes an excellent light-source analyzer. About
    as good as (or better than) anything you might find in a simple physics lab. How
    many of you even knew that compact fluorescents put out a "cleaner" white than
    ballast powered ones until now? You can see it happening if your camera is
    equipped to see it.

    Taking video under fluorescent lights is even a greater challenge to get white
    balance right.

    Just because you can't see it happening doesn't mean it's not there. :)

    I often wonder if people who post those elaborate white-balance tests online are
    even aware of this. They never seem to be.
     
    Hank Meillsen, Nov 7, 2007
    #7
  8. digi

    George Kerby Guest

    On 11/7/07 12:06 AM, in article oBcYi.1923$, "Stefan
    Patric" <> wrote:

    > On Mon, 05 Nov 2007 05:52:22 -0500, Joseph Meehan wrote:
    >
    >> "Stefan Patric" <> wrote in message
    >> news:mcwXi.873$...
    >>> On Sat, 03 Nov 2007 18:15:28 -0700, digi wrote:
    >>>
    >>>> I have a Nikon Coolpix 7900 that is about 3 years old. I am
    >>>> considering replacing this camera with another point and shoot digital
    >>>> camera (not SLR), because the quality of the pictures I take in
    >>>> florescent lighting is poor. I have tried resetting the white balance
    >>>> feature and that didn't help.
    >>>> [snip]
    >>>
    >>> Learn how to use fill flash and color compensation/correction filters
    >>> over the flash to balance it to the ambient light.

    >>
    >> As suggested the flash would need to be "corrected" to match
    >> whatever
    >> florescent light was in use. This could be next to impossible for a
    >> professional and likely impossible for the vast majority of us real
    >> people.

    >
    > Not anywhere near next to impossible: Difficult, sometimes; fairly easy,
    > most of the time. Did it for years, when all there was was film. With
    > digital, it's a snap.
    >
    >>> As to color balance, get a camera that has a Custom White Balance
    >>> option, where you point the camera at a white target (I use general
    >>> sheet of acid- free, drawing paper) under the light source you're
    >>> shooting under and click the shutter. You're color balanced or, at
    >>> least, color balanced to the best the camera can be. Tweak in
    >>> Photoshop.

    >>
    >> Yes that is about the best and only solution available. I would
    >> also
    >> suggest that different cameras have different abilities and some
    >> experimentation may prove helpful.
    >>
    >> Balancing florescent is a challenge for all photographers and and
    >> cameras as there are so many different "florescent" colors and they are
    >> "bright line" not continuous colors so they do some very strange things.

    >
    > FWIW: 97% or so of all fluorescent tubes used in commercial and
    > residential buildings are Cool Whites. A .30 to .35 Magenta filter over
    > the camera lens with the camera color balance set to "Daylight" will get
    > you within a few points of balanced 98% of the time. The other 2.9% of
    > the tubes are Warm White Deluxe, which are almost dead-on 3200K color
    > temperature. Set your camera to Tungsten. No filter needed. Tweak in
    > post.
    >
    > To balance flash to Cool Whites, Rosco Industries' "Window Green" works
    > great!
    >
    > In some industrial uses, and convention and exhibit halls, the artificial
    > lighting is true daylight balanced. Usually no correction is need or at
    > most, set the camera to "Electronic Flash" to warm things up a little.
    >
    > Check out Rosco's web site. They have just about any color correction,
    > color alteration media you'll ever need. http://www.rosco.com/ Or
    > almost as good is http://www.leefilters.com/
    >
    > Stef

    I'm so glad SOMEONE came into this thread that knew what the hell they were
    talking about. The rest is NOISE. Thanks, Stef, for some facts!
     
    George Kerby, Nov 7, 2007
    #8
  9. "Stefan Patric" <> wrote in message
    news:eek:BcYi.1923$...
    > On Mon, 05 Nov 2007 05:52:22 -0500, Joseph Meehan wrote:
    >

    ....
    >>
    >> As suggested the flash would need to be "corrected" to match
    >> whatever
    >> florescent light was in use. This could be next to impossible for a
    >> professional and likely impossible for the vast majority of us real
    >> people.

    >
    > Not anywhere near next to impossible: Difficult, sometimes; fairly easy,
    > most of the time. Did it for years, when all there was was film. With
    > digital, it's a snap.
    >

    ...
    >>
    >> Yes that is about the best and only solution available. I would
    >> also
    >> suggest that different cameras have different abilities and some
    >> experimentation may prove helpful.
    >>
    >> Balancing florescent is a challenge for all photographers and and
    >> cameras as there are so many different "florescent" colors and they are
    >> "bright line" not continuous colors so they do some very strange things.

    >
    > FWIW: 97% or so of all fluorescent tubes used in commercial and
    > residential buildings are Cool Whites.


    I would not say 97%, but it is a high percetage.

    > A .30 to .35 Magenta filter over
    > the camera lens with the camera color balance set to "Daylight" will get
    > you within a few points of balanced 98% of the time.


    It is not that simple. If you are talking about balancing a gray card,
    yea, I could agree with that. However when you are trying to balance skin
    tones, someone's wedding dress, or maybe a painting or just about any real
    life subject, it is more like 18% of the time. Of course that does depend
    on your personal judgment of what is acceptable.


    > The other 2.9% of
    > the tubes are Warm White Deluxe, which are almost dead-on 3200K color
    > temperature. Set your camera to Tungsten. No filter needed. Tweak in
    > post.


    Sure, but they are not smooth spectrum, so they seldom are close to real
    life results.


    >
    > To balance flash to Cool Whites, Rosco Industries' "Window Green" works
    > great!
    >
    > In some industrial uses, and convention and exhibit halls, the artificial
    > lighting is true daylight balanced. Usually no correction is need or at
    > most, set the camera to "Electronic Flash" to warm things up a little.


    Same problems.

    It appears that you lack real life experience or you have a much wider
    range of what is acceptable than I do.

    >
    > Check out Rosco's web site. They have just about any color correction,
    > color alteration media you'll ever need. http://www.rosco.com/ Or
    > almost as good is http://www.leefilters.com/
    >
    > Stef


    --
    Joseph Meehan

    Dia 's Muire duit
     
    Joseph Meehan, Nov 7, 2007
    #9
  10. digi

    Marty Fremen Guest

    Hank Meillsen <hmeillsen@no_spams.com> wrote:

    > How
    > many of you even knew that compact fluorescents put out a "cleaner"
    > white than ballast powered ones until now? You can see it happening if
    > your camera is equipped to see it.
    >


    The compact fluorescents I have give a pronounced lemon yellow colour,
    presumably to mimic the warm colours people are accustomed to with
    tungsten lighting. The tint isn't obvious to the eye until you try
    taking a photo using daylight balance. I find custom white balance gives
    a very good correction to the colour cast, perhaps a slight
    overcorrection in fact, I find it looks better if I red-shift the
    resultant white balance to restore a hint of warmth to the light. Some
    auto white balances do a modestly good job too, but as with all
    fluorescents it's better to do a custom setting.

    I think compact fluorecents typically flicker around 30KHz instead of
    the 100/120Hz that normal strip lights do, so there shouldn't be any
    problem regarding clashes between shutter speed and flicker etc.
     
    Marty Fremen, Nov 8, 2007
    #10
  11. On 08 Nov 2007 02:32:15 GMT, Marty Fremen <> wrote:

    >Hank Meillsen <hmeillsen@no_spams.com> wrote:
    >
    >> How
    >> many of you even knew that compact fluorescents put out a "cleaner"
    >> white than ballast powered ones until now? You can see it happening if
    >> your camera is equipped to see it.
    >>

    >
    >The compact fluorescents I have give a pronounced lemon yellow colour,
    >presumably to mimic the warm colours people are accustomed to with
    >tungsten lighting. The tint isn't obvious to the eye until you try
    >taking a photo using daylight balance. I find custom white balance gives
    >a very good correction to the colour cast, perhaps a slight
    >overcorrection in fact, I find it looks better if I red-shift the
    >resultant white balance to restore a hint of warmth to the light. Some
    >auto white balances do a modestly good job too, but as with all
    >fluorescents it's better to do a custom setting.
    >
    >I think compact fluorecents typically flicker around 30KHz instead of
    >the 100/120Hz that normal strip lights do, so there shouldn't be any
    >problem regarding clashes between shutter speed and flicker etc.


    My reference to "cleaner" here wasn't in reference to how pure white it is, but
    that compact fluorescents, due to the high-frequency alternating current that
    they use, doesn't interfere in the slower shutter speeds used by cameras. Where
    the ballast powered 60/50Hz cycles do (not 100/120, that's household voltage in
    parts of the world). It's not just that they put out white, but while trying to
    do so they are cycling through a whole range of colors and intensities every
    60th of a second. That's the problem.

    Regarding the yellow tint you find in your particular variety of compact
    fluorescents, at least you will be able to correct for it using your manual
    white-balance mode. Now imagine if that same light was cycling from yellow to
    blue and back again once every 60th of a second, and you only sampled 1/2 of
    that cycle. Which half will your camera adjust for? Not to mention it will be
    impossible for your camera to always sample the same part of that cycle from one
    attempt to the next.

    See the problem?

    ASCII graph attempt:

    1/60th second fluorescent light cycle =

    bluish whitish whitish whitish yellowish reddish darker dark bluish

    ^ here .........to .... here ^


    "Here to here" denoting your shutter speed or manual white-balance exposure
    segment of that cycle.

    Your camera is going to try to adjust your image or white-balance for a dark
    purplish color. But to your eyes all you see is that cycle being blended into
    the yellowish white. Your human perception can't see the light changing all
    those colors and intensities that fast.

    Maybe someone else can explain it to you more clearly.
     
    Hank Meillsen, Nov 8, 2007
    #11
  12. digi

    Marty Fremen Guest

    Hank Meillsen <hmeillsen@no_spams.com> wrote:

    > Where
    > the ballast powered 60/50Hz cycles do (not 100/120, that's household
    > voltage in parts of the world).


    Normal fluorescents do flash at 100 or 120 Hz - twice per AC cycle, on
    the positive and negative peaks. If they flashed at 50 or 60 Hz it would
    be *very* noticeable! Consider that a monitor has to refresh at about
    85Hz to be flicker free, and it only fills a fairly small portion of
    your visual field.
     
    Marty Fremen, Nov 8, 2007
    #12
  13. On 08 Nov 2007 19:09:53 GMT, Marty Fremen <> wrote:

    >Hank Meillsen <hmeillsen@no_spams.com> wrote:
    >
    >> Where
    >> the ballast powered 60/50Hz cycles do (not 100/120, that's household
    >> voltage in parts of the world).

    >
    >Normal fluorescents do flash at 100 or 120 Hz - twice per AC cycle, on
    >the positive and negative peaks. If they flashed at 50 or 60 Hz it would
    >be *very* noticeable! Consider that a monitor has to refresh at about
    >85Hz to be flicker free, and it only fills a fairly small portion of
    >your visual field.


    True, but that's not 100 or 120 identical cycles. You are counting 2 different
    halves of 1 cycle. The color shifts and phosphor luminosity rampings are not
    identical on both sides of a single AC cycle. I usually don't reference 2
    different cycles as one. I guess your not knowing this and the fact that I was
    talking about this very problem made it easy to mistake you for referencing
    voltage. There's a reason that straight fluorescents erode more rapidly at one
    starter filament than the other and to extend their life you can turn them
    around in their fixtures.
     
    Hank Meillsen, Nov 8, 2007
    #13
  14. digi

    JosephKK Guest

    Hank Meillsen hmeillsen@no_spams.com posted to rec.photo.digital:

    > On 08 Nov 2007 19:09:53 GMT, Marty Fremen <>
    > wrote:
    >
    >>Hank Meillsen <hmeillsen@no_spams.com> wrote:
    >>
    >>> Where
    >>> the ballast powered 60/50Hz cycles do (not 100/120, that's
    >>> household voltage in parts of the world).

    >>
    >>Normal fluorescents do flash at 100 or 120 Hz - twice per AC cycle,
    >>on the positive and negative peaks. If they flashed at 50 or 60 Hz
    >>it would be *very* noticeable! Consider that a monitor has to
    >>refresh at about 85Hz to be flicker free, and it only fills a fairly
    >>small portion of your visual field.

    >
    > True, but that's not 100 or 120 identical cycles. You are counting 2
    > different halves of 1 cycle. The color shifts and phosphor
    > luminosity rampings are not identical on both sides of a single AC
    > cycle. I usually don't reference 2 different cycles as one. I guess
    > your not knowing this and the fact that I was talking about this
    > very problem made it easy to mistake you for referencing voltage.
    > There's a reason that straight fluorescents erode more rapidly at
    > one starter filament than the other and to extend their life you can
    > turn them around in their fixtures.


    I have no idea where you are getting your incredible poppycock.
    Willful ignorance compounded by piss poor judgment. Read some
    of "How Things Work" series. Fluorescents that erode more at one end
    are caused by faulty ballasts, which should be replaced as well.
     
    JosephKK, Nov 10, 2007
    #14
  15. digi

    Robert Coe Guest

    On 08 Nov 2007 19:09:53 GMT, Marty Fremen <> wrote:
    : Hank Meillsen <hmeillsen@no_spams.com> wrote:
    :
    : > Where
    : > the ballast powered 60/50Hz cycles do (not 100/120, that's household
    : > voltage in parts of the world).
    :
    : Normal fluorescents do flash at 100 or 120 Hz - twice per AC cycle, on
    : the positive and negative peaks. If they flashed at 50 or 60 Hz it would
    : be *very* noticeable!

    Fluorescent bulbs flicker at line frequency. If the flicker rate appears to be
    twice line frequency, it's probably because the light is coming from a fixture
    containing two or more bulbs wired to different phase angles. (Or you could
    double the frequency in the ballast; but I don't know whether that's ever
    done, since it would add to the cost of the fixture and probably generate
    extra heat.)

    : Consider that a monitor has to refresh at about 85Hz to be flicker free,
    : and it only fills a fairly small portion of your visual field.

    Actually, the main reason a monitor flickers so badly at line frequency (60 Hz
    in the US) is that it resonates with ambient fluorescent light. Light the room
    with incandescent bulbs, and the perceived flicker of a 60Hz monitor goes way
    down. (Incandescent lights flicker, but with a much smaller amplitude
    variation than fluorescents.) The reason an 85Hz monitor doesn't appear to
    flicker is that 85 Hz is far enough from the line frequency to avoid the
    resonance. 60 Hz is plenty fast enough to fool the eye unless you blink or
    turn away slightly. Note that flicker isn't usually a problem in movie
    theaters. I forget what the flicker rate of a commercial movie projector is,
    but it's certainly less than 60 Hz.

    Bob
     
    Robert Coe, Nov 12, 2007
    #15
  16. digi

    Marty Fremen Guest

    Robert Coe <> wrote:

    > On 08 Nov 2007 19:09:53 GMT, Marty Fremen <>
    > wrote:
    >: Hank Meillsen <hmeillsen@no_spams.com> wrote:
    >:
    >: > Where
    >: > the ballast powered 60/50Hz cycles do (not 100/120, that's
    >: > household voltage in parts of the world).
    >:
    >: Normal fluorescents do flash at 100 or 120 Hz - twice per AC cycle,
    >: on the positive and negative peaks. If they flashed at 50 or 60 Hz it
    >: would be *very* noticeable!
    >
    > Fluorescent bulbs flicker at line frequency. If the flicker rate
    > appears to be twice line frequency, it's probably because the light is
    > coming from a fixture containing two or more bulbs wired to different
    > phase angles.


    Maybe in the US (very doubtful though) but certainly not in the UK. There
    are two peaks in each mains cycle: +240V and -240V and each generates a
    flash of light.

    > Actually, the main reason a monitor flickers so badly at line
    > frequency (60 Hz in the US) is that it resonates with ambient
    > fluorescent light. Light the room with incandescent bulbs, and the
    > perceived flicker of a 60Hz monitor goes way down.


    The levels at which flicker is perceptible have been the subject of plenty
    of ergonomics research over the years. Although it varies from person to
    person, for CRTs, a good minimum to go for is 65Hz for light text on a
    black background, 85Hz for black text on a white background. Lower refresh
    rates will tend to cause fatigue and stress and require frequent breaks.
    LCDs are somewhat different, the light is usually coming from a 100Hz
    fluorescent backlight so the refresh rate of the LCDs themselves can be
    lower. TVs are different again because normal TV viewing distances mean
    they usually subtend a much smaller visual angle, and the on-screen
    movement also serves to disguise the flicker. With fluorescent lighting,
    the whole visual field is flashing so a higher rate is needed. 100Hz
    lighting is certainly noticeable by most people (that is, they can
    distinguish it from a steady light), but most people don't find it
    unacceptable. However some people find it gives them a headache. Similarly
    some people don't like using CRTs below 100Hz. IIRC you would need to
    increase the rate to at least 150Hz before the signal ceases to register in
    EEG readings.

    > 60 Hz is plenty fast enough to fool the eye unless you blink or
    > turn away slightly.


    No. Read the ergonomics research. This was all established decades ago.

    >Note that flicker isn't usually a problem in movie
    > theaters. I forget what the flicker rate of a commercial movie
    > projector is, but it's certainly less than 60 Hz.


    No, it's more. They open and close the projector's shutter several times
    per frame to raise the flicker rate beyond a problematic threshold. In
    addition, the on-screen action helps disguise flicker.
     
    Marty Fremen, Nov 12, 2007
    #16
  17. digi

    RickR Guest

    On Nov 7, 6:37 am, George Kerby <> wrote:
    > On 11/7/07 12:06 AM, in article oBcYi.1923$, "Stefan
    >
    > I'm so glad SOMEONE came into this thread that knew what the hell they were
    > talking about. The rest is NOISE. Thanks, Stef, for some facts!- Hide quoted text -
    >


    One more fact to consider:

    Modern fluorescents, including screw-in retrofits, use electronic
    ballasts. These range in frequency from 20,000 to 50,000Hz.

    Not only are these well beyond the limits of human perception, but the
    faster ones are beyond the phosphors limits. The phosphor does not
    fade between pulses! No flicker.

    RickR
     
    RickR, Nov 13, 2007
    #17
  18. digi

    JosephKK Guest

    Robert Coe posted to rec.photo.digital:

    > On 08 Nov 2007 19:09:53 GMT, Marty Fremen <>
    > wrote:
    > : Hank Meillsen <hmeillsen@no_spams.com> wrote:
    > :
    > : > Where
    > : > the ballast powered 60/50Hz cycles do (not 100/120, that's
    > : > household voltage in parts of the world).
    > :
    > : Normal fluorescents do flash at 100 or 120 Hz - twice per AC
    > : cycle, on the positive and negative peaks. If they flashed at 50
    > : or 60 Hz it would be *very* noticeable!
    >
    > Fluorescent bulbs flicker at line frequency. If the flicker rate
    > appears to be twice line frequency, it's probably because the light
    > is coming from a fixture containing two or more bulbs wired to
    > different phase angles. (Or you could double the frequency in the
    > ballast; but I don't know whether that's ever done, since it would
    > add to the cost of the fixture and probably generate extra heat.)


    NO! They flicker at twice line frequency. One ionization pulse for
    each half cycle. Even that is damped by the fluorescent decay.

    The best ballasts now drive the lamp at 40 kHz to 200 kHz, far far
    faster than the time response of the phosphors, and they are not
    expensive any more either.


    >
    > : Consider that a monitor has to refresh at about 85Hz to be flicker
    > : free, and it only fills a fairly small portion of your visual
    > : field.


    Actually a bunch of horseshit originated by David Em and propagated by
    Jerry Pournell in the 1970s and 1980s.

    >
    > Actually, the main reason a monitor flickers so badly at line
    > frequency (60 Hz in the US) is that it resonates with ambient

    ^^^^^^^^^ make that beats
    (interferes)
    > fluorescent light. Light the room with incandescent bulbs, and the
    > perceived flicker of a 60Hz monitor goes way down. (Incandescent
    > lights flicker, but with a much smaller amplitude variation than
    > fluorescents.) The reason an 85Hz monitor doesn't appear to flicker
    > is that 85 Hz is far enough from the line frequency to avoid the
    > resonance. 60 Hz is plenty fast enough to fool the eye unless you
    > blink or turn away slightly. Note that flicker isn't usually a
    > problem in movie theaters. I forget what the flicker rate of a
    > commercial movie projector is, but it's certainly less than 60 Hz.
    >
    > Bob


    Aye, and the standard frame rate of film movies is 24 frames per
    second, with scant noticeable flicker!
     
    JosephKK, Nov 14, 2007
    #18
  19. digi

    JosephKK Guest

    Marty Fremen lid posted to rec.photo.digital:

    > Robert Coe <> wrote:
    >
    >> On 08 Nov 2007 19:09:53 GMT, Marty Fremen <>
    >> wrote:
    >>: Hank Meillsen <hmeillsen@no_spams.com> wrote:
    >>:
    >>: > Where
    >>: > the ballast powered 60/50Hz cycles do (not 100/120, that's
    >>: > household voltage in parts of the world).
    >>:
    >>: Normal fluorescents do flash at 100 or 120 Hz - twice per AC
    >>: cycle, on the positive and negative peaks. If they flashed at 50
    >>: or 60 Hz it would be *very* noticeable!
    >>
    >> Fluorescent bulbs flicker at line frequency. If the flicker rate
    >> appears to be twice line frequency, it's probably because the light
    >> is coming from a fixture containing two or more bulbs wired to
    >> different phase angles.

    >
    > Maybe in the US (very doubtful though) but certainly not in the UK.
    > There are two peaks in each mains cycle: +240V and -240V and each
    > generates a flash of light.
    >
    >> Actually, the main reason a monitor flickers so badly at line
    >> frequency (60 Hz in the US) is that it resonates with ambient
    >> fluorescent light. Light the room with incandescent bulbs, and the
    >> perceived flicker of a 60Hz monitor goes way down.

    >
    > The levels at which flicker is perceptible have been the subject of
    > plenty of ergonomics research over the years. Although it varies
    > from person to person, for CRTs, a good minimum to go for is 65Hz
    > for light text on a black background, 85Hz for black text on a white
    > background. Lower refresh rates will tend to cause fatigue and
    > stress and require frequent breaks. LCDs are somewhat different, the
    > light is usually coming from a 100Hz fluorescent backlight so the
    > refresh rate of the LCDs themselves can be lower. TVs are different
    > again because normal TV viewing distances mean they usually subtend
    > a much smaller visual angle, and the on-screen movement also serves
    > to disguise the flicker. With fluorescent lighting, the whole visual
    > field is flashing so a higher rate is needed. 100Hz lighting is
    > certainly noticeable by most people (that is, they can distinguish
    > it from a steady light), but most people don't find it unacceptable.
    > However some people find it gives them a headache. Similarly some
    > people don't like using CRTs below 100Hz. IIRC you would need to
    > increase the rate to at least 150Hz before the signal ceases to
    > register in EEG readings.
    >
    >> 60 Hz is plenty fast enough to fool the eye unless you blink or
    >> turn away slightly.

    >
    > No. Read the ergonomics research. This was all established decades
    > ago.


    Really? Citations please.
    >
    >>Note that flicker isn't usually a problem in movie
    >> theaters. I forget what the flicker rate of a commercial movie
    >> projector is, but it's certainly less than 60 Hz.

    >
    > No, it's more. They open and close the projector's shutter several
    > times per frame to raise the flicker rate beyond a problematic
    > threshold. In addition, the on-screen action helps disguise flicker.


    Horseshit! The movie frame rate has been 24 frames per second for
    essentially all of the 20th century. It still is for film
    projectors. Your magic project shutters are make-believe, and would
    have been a reliability nightmare.
    If on screen action were such a boon, why doesn't it work for computer
    monitors?
     
    JosephKK, Nov 14, 2007
    #19
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