Reproducing white at ISO 100

Discussion in 'Digital Photography' started by ronviers@gmail.com, Mar 22, 2006.

  1. Guest

    When I shoot a white backdrop at ISO 100 the result is gray. The
    histogram shows the information to be in the center. Why is that? I
    have tried various light levels and apertures but it stays gray. I can
    get it to be white if I use a higher ISO.

    Thanks,
    Ron
     
    , Mar 22, 2006
    #1
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  2. Scott W Guest

    wrote:
    > When I shoot a white backdrop at ISO 100 the result is gray. The
    > histogram shows the information to be in the center. Why is that? I
    > have tried various light levels and apertures but it stays gray. I can
    > get it to be white if I use a higher ISO.
    >
    > Thanks,
    > Ron


    Expsoure meters tend to assume that average scene will be at 18% of
    white. So when you photograph a uniform scene like a backdrop it will
    come out at about 18% gray.

    You need to use you EV adjustment to correct for this, or you can edit
    that photo after the fact. In tricky lighting it is a good idea to
    look at the histogram of the photo to see how the exposure is coming
    out.

    Scott
     
    Scott W, Mar 22, 2006
    #2
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  3. Guest

    Hi Scott, thank you for information.
    Why didn't I think of that. I am using manual mode so I just stopped
    up two clicks past when the indicator pegs and it worked perfectly.
    Until I learn what I am doing I will take a practice picture picture,
    check the histogram, then reset the exposure. The only problem I had
    was that I had to close the aperture a tad to allow for the increased
    time but for these photos it will not be the end of the world.

    Thanks again
     
    , Mar 22, 2006
    #3
  4. Guest

    Hi Scott, thank you for information.
    Why didn't I think of that. I am using manual mode so I just stopped
    up two clicks past when the indicator pegs and it worked perfectly.
    Until I learn what I am doing I will take a practice picture picture,
    check the histogram, then reset the exposure. The only problem I had
    was that I had to close the aperture a tad to allow for the increased
    time but for these photos it will not be the end of the world.

    Thanks again
     
    , Mar 22, 2006
    #4
  5. Rich Guest

    On 22 Mar 2006 08:37:54 -0800, ""
    <> wrote:

    >When I shoot a white backdrop at ISO 100 the result is gray. The
    >histogram shows the information to be in the center. Why is that? I
    >have tried various light levels and apertures but it stays gray. I can
    >get it to be white if I use a higher ISO.
    >
    >Thanks,
    >Ron


    Everyone must learn the Zone System. Ansel's work still has
    value.
    -Rich
     
    Rich, Mar 22, 2006
    #5
  6. Jim Townsend Guest

    wrote:


    > Until I learn what I am doing I will take a practice picture picture,
    > check the histogram, then reset the exposure.


    I KNOW what I'm doing, yet I still check the histogram often to make
    sure the exposure is right :)
     
    Jim Townsend, Mar 22, 2006
    #6
  7. Scott W Guest

    Rich wrote:
    > On 22 Mar 2006 08:37:54 -0800, ""
    > <> wrote:
    >
    > >When I shoot a white backdrop at ISO 100 the result is gray. The
    > >histogram shows the information to be in the center. Why is that? I
    > >have tried various light levels and apertures but it stays gray. I can
    > >get it to be white if I use a higher ISO.
    > >
    > >Thanks,
    > >Ron

    >
    > Everyone must learn the Zone System. Ansel's work still has


    This is pretty basic stuff, I don't think we really need to bring the
    Zone system in for this one.

    Scott
     
    Scott W, Mar 22, 2006
    #7
  8. secheese Guest

    On Wed, 22 Mar 2006 13:52:41 -0600, Jim Townsend <>
    wrote:

    > wrote:
    >
    >
    >> Until I learn what I am doing I will take a practice picture picture,
    >> check the histogram, then reset the exposure.

    >
    >I KNOW what I'm doing, yet I still check the histogram often to make
    >sure the exposure is right :)


    The histogram doesn't indicate right or wrong exposure, any more than
    a thermometer indicates right or wrong temperature. It's up to the
    photographer to interpret what the histogram is displaying. For
    example, I may intentionally overexpose a snowy scene and have the
    histogram indicate many pixels at the high end. Is this wrong? Of
    course not; it's what I wanted.
     
    secheese, Mar 22, 2006
    #8
  9. Scott W Guest

    secheese wrote:
    > On Wed, 22 Mar 2006 13:52:41 -0600, Jim Townsend <>
    > wrote:
    >
    > > wrote:
    > >
    > >
    > >> Until I learn what I am doing I will take a practice picture picture,
    > >> check the histogram, then reset the exposure.

    > >
    > >I KNOW what I'm doing, yet I still check the histogram often to make
    > >sure the exposure is right :)

    >
    > The histogram doesn't indicate right or wrong exposure, any more than
    > a thermometer indicates right or wrong temperature. It's up to the
    > photographer to interpret what the histogram is displaying. For
    > example, I may intentionally overexpose a snowy scene and have the
    > histogram indicate many pixels at the high end. Is this wrong? Of
    > course not; it's what I wanted.


    In this case the histogram will tell you if the exposure is wrong. He
    has a large unifrom surface that he wants to come out white, pretty
    easy to see this on a histogram.

    Scott
     
    Scott W, Mar 23, 2006
    #9
  10. "Scott W" <> wrote:
    > Rich wrote:
    >>
    >> Everyone must learn the Zone System. Ansel's work still has

    >
    > This is pretty basic stuff, I don't think we really need to bring the
    > Zone system in for this one.


    The whole zone system is a bit overmuch, but zone exposure is certainly
    worth learning. This guy's books explain it quite well. Another book worth
    reading is "The Zone System for 35mm Photographers". I find it's
    descriptions and examples of the different zones useful, although the
    reproduction of the photos in the book is way too flat (they don't have a
    good black).

    http://www.spotmetering.com/

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Mar 23, 2006
    #10
  11. Guest

    Hi David,
    I took a cursory look at Wikipedia and it certainly looks like it is
    worth learning and it seems to be where I am in my work. Books for now
    are not an option, I learned a long time ago how to get a computer to
    dispense a pellet of food by pushing the buttons in just the right
    order, but as hard as I try the camera refuses to come across with
    anything - even a crumb, so I will have to use the web to learn the
    Zone System but I found a bunch of references so it should not be a
    problem.
    I have found books rarely have good blacks. I knew this chick with
    book on blacks. Each page was a different black, very cool.
    What is your favorite book to look at in terms of photos and quality
    reprints?

    Thanks,
    Ron
     
    , Mar 23, 2006
    #11
  12. Guest

    Hi David,
    I took a cursory look at Wikipedia and it certainly looks like it is
    worth learning and it seems to be where I am in my work. Books for now
    are not an option, I learned a long time ago how to get a computer to
    dispense a pellet of food by pushing the buttons in just the right
    order, but as hard as I try the camera refuses to come across with
    anything - even a crumb, so I will have to use the web to learn the
    Zone System but I found a bunch of references so it should not be a
    problem.
    I have found books rarely have good blacks. I knew this chick with
    book on blacks. Each page was a different black, very cool.
    What is your favorite book to look at in terms of photos and quality
    reprints?

    Thanks,
    Ron
     
    , Mar 23, 2006
    #12
  13. timeOday Guest

    wrote:
    > When I shoot a white backdrop at ISO 100 the result is gray. The
    > histogram shows the information to be in the center. Why is that?


    How would your camera know the difference between an all-white image and
    an all-gray one?
     
    timeOday, Mar 23, 2006
    #13
  14. Guest

    The reality was white, the image produced by the camera was gray. I
    can say with a high degree of confidence that the camera didn't know,
    but I am almost certain that it didn't care.
     
    , Mar 23, 2006
    #14
  15. Rich Guest

    On Thu, 23 Mar 2006 09:29:32 +0900, "David J. Littleboy"
    <> wrote:

    >
    >"Scott W" <> wrote:
    >> Rich wrote:
    >>>
    >>> Everyone must learn the Zone System. Ansel's work still has

    >>
    >> This is pretty basic stuff, I don't think we really need to bring the
    >> Zone system in for this one.

    >
    >The whole zone system is a bit overmuch, but zone exposure is certainly
    >worth learning. This guy's books explain it quite well. Another book worth
    >reading is "The Zone System for 35mm Photographers". I find it's
    >descriptions and examples of the different zones useful, although the
    >reproduction of the photos in the book is way too flat (they don't have a
    >good black).
    >
    >http://www.spotmetering.com/
    >
    >David J. Littleboy
    >Tokyo, Japan
    >


    The Print, The Negative and The Camera were pretty decently printed
    back when. I don't know what recent ones are like.
    -Rich
     
    Rich, Mar 23, 2006
    #15
  16. secheese <> wrote:
    >The histogram doesn't indicate right or wrong exposure, any more than
    >a thermometer indicates right or wrong temperature. It's up to the
    >photographer to interpret what the histogram is displaying. For
    >example, I may intentionally overexpose a snowy scene and have the
    >histogram indicate many pixels at the high end. Is this wrong? Of
    >course not; it's what I wanted.


    You do *not* want to "overexpose" a snowy scene. The problem is
    that if you let the camera set the exposure without compensation,
    it will *under expose* the scene. (And as the OP said, all the
    pixels will be in the middle of the histogram.) When the scene
    is *properly* exposed, it will have many pixels at the high end.

    --
    Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
    Ukpeagvik (Barrow, Alaska)
     
    Floyd L. Davidson, Mar 23, 2006
    #16
  17. "Floyd L. Davidson" <> wrote:
    >
    > You do *not* want to "overexpose" a snowy scene. The problem is
    > that if you let the camera set the exposure without compensation,
    > it will *under expose* the scene.


    (Don't take this personally: you've treaded too close to one of my pet
    peeves<g>.)

    This is an improvement, but I still disagree with this expression of the
    issue.

    If you set a camera to auto mode and point it at a snowy scene, the camera
    does _exactly_ what you told it to do; it places the snow (the main subject)
    at mid-gray.

    The _camera_ didn't under expose the scene, the idiot photographer did. The
    idiot photographer wanted an image to look like something he had in mind but
    failed to communicate that to the camera.

    > (And as the OP said, all the
    > pixels will be in the middle of the histogram.) When the scene
    > is *properly* exposed, it will have many pixels at the high end.


    There's no such thing as "properly exposed". At night, you may want to place
    the snow at zone IV or even zone III.

    That's why I recommend "The Confused Photographer's Guide to On-Camera
    Spotmetering".

    http://www.spotmetering.com/

    This book bangs the concepts into your head 17 different ways.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Mar 23, 2006
    #17
  18. "David J. Littleboy" <> wrote:
    >"Floyd L. Davidson" <> wrote:
    >>
    >> You do *not* want to "overexpose" a snowy scene. The problem is
    >> that if you let the camera set the exposure without compensation,
    >> it will *under expose* the scene.

    >
    >(Don't take this personally: you've treaded too close to one of my pet
    >peeves<g>.)


    I don't disagree with anything you've said. (I was trying to be
    at least a little bit, errr, diplomatic, about it.) Your
    comments are the *perfect* continuation of mine. Thank you for
    the additional enlightenment!

    >This is an improvement, but I still disagree with this expression of the
    >issue.
    >
    >If you set a camera to auto mode and point it at a snowy scene, the camera
    >does _exactly_ what you told it to do; it places the snow (the main subject)
    >at mid-gray.
    >
    >The _camera_ didn't under expose the scene, the idiot photographer did. The
    >idiot photographer wanted an image to look like something he had in mind but
    >failed to communicate that to the camera.
    >
    >> (And as the OP said, all the
    >> pixels will be in the middle of the histogram.) When the scene
    >> is *properly* exposed, it will have many pixels at the high end.

    >
    >There's no such thing as "properly exposed". At night, you may want to place
    >the snow at zone IV or even zone III.
    >
    >That's why I recommend "The Confused Photographer's Guide to On-Camera
    >Spotmetering".
    >
    >http://www.spotmetering.com/
    >
    >This book bangs the concepts into your head 17 different ways.
    >
    >David J. Littleboy
    >Tokyo, Japan


    --
    Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
    Ukpeagvik (Barrow, Alaska)
     
    Floyd L. Davidson, Mar 23, 2006
    #18
  19. acl Guest

    wrote:
    > The reality was white, the image produced by the camera was gray. I
    > can say with a high degree of confidence that the camera didn't know,
    > but I am almost certain that it didn't care.
    >



    Try the following: switch to spotmetering (if your camera has, or
    partial if not), and find a white area. Meter from there and shoot; then
    add +0.5 stop and shoot, and do this up to (say) 3 stops. Then, look at
    the resulting images and their corresponding histograms. You'll find
    that the first (ie as metered) is, as you have already observed in your
    example, gray, and the histogram bunched in the middle. as the
    compensation increases in successive shots, the photo shifts towards
    white, and at the same time the histogram moves to the right. You'll
    find that for a white that does look white, the histogram is bunched to
    the right.

    Another thing to think about is this: It is impossible (literally) to
    distinguish between a dimly-lit white wall and a brightly-lit gray one
    by just analysing incoming light (ie your camera's meter cannot tell,
    even in principle, if it's a dark room and white wall or a bright room
    and grey wall). So, it assumes it is a particular kind of gray.

    You might like thinking about the following: Metering works by detecting
    phonons. Suppose I have an ideal black object; by its very definition,
    this does not reflect any of the incoming light (real black objects do
    reflect some light, obviously). Therefore, when I spotmeter off this
    object, me meter detects no or very few photons; but how can it tell if
    it's looking at something black or at something eg white but very dimly
    lit? It doesn't you have to tell it (by dialling exposure compensation,
    eg -2 stops, experiment a bit with your camera to find out what works).

    Hope that's understandable.
     
    acl, Mar 23, 2006
    #19
  20. acl Guest

    acl wrote:
    > phonons. Suppose I have an ideal black object; by its very definition,


    Photons! Sorry.
     
    acl, Mar 23, 2006
    #20
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