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Thread: Perception of light and illumination in practice

  1. #1
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    Default Perception of light and illumination in practice

    With reference from this thread, let's discuss!
    Last edited by hazmee; 15th November 2008 at 10:00 AM.

  2. #2

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by hazmee View Post
    Let's discuss!
    You have some really good examples in Flickr. I feel that your images will illustrate this concept better than some.
    Last edited by photobum; 15th November 2008 at 10:04 AM.

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    Default Re: Perception of light and illumination in practice


  4. #4

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by hazmee View Post

    Of course. Imran's works are ideal. He is considered one of the few masters of light.

    You know him well?

    Here is a great example to illustration the concept.
    http://www.fotobyimran.com/images/20...2__mg_8232.jpg
    Last edited by roygoh; 19th November 2008 at 04:45 AM.

  5. #5

    Default Re: Perception of light and illumination in practice

    After we have seen Imran's work, we will know what is wrong with Andrew's.

    Anyway, I have noticed that many CSers are seriously lacking in this ability to see and understand light. It is very thoughtful of you to start this thread.
    Last edited by photobum; 15th November 2008 at 10:23 AM.

  6. #6

    Default Re: Perception of light and illumination in practice

    er, so you're saying that a backlit fishing rod will glow unnaturally from the front facing the camera?

    i like imran's works, but he doesn't ALWAYS keep the hierachy of light

    as for the discussed work that photobum edited, i thought should retain the boat in photobum's picture; but the wave details are all gone.
    Last edited by night86mare; 15th November 2008 at 02:08 PM.

  7. #7

    Default Re: Perception of light and illumination in practice

    another example where imran doesn't employ the strict use of hierachy of light. yet another.

    but here it is kept. personally, i don't think it's really that important - so long as your purpose is stated clearly? there is after all, a significant difference between a vein of digital art versus pure photography, etc. most of the good professional landscape photographers (who shoot primarily landscapes) tend to keep the hierachy of light relatively well - example i can name off the top of my head would be marc adamus and adam burton.

    if i have misunderstood the discussion point here - i.e. that light and illumination has nothing to do with the bright points being realistically bright, etc, due to light source direction - i call it the hierachy of light.. then i apologise in advance.

    there are examples where it matters not; for example, light painting in landscapes frequently defies all form and idea of illumination sources + light direction, etc.

    for example, mike stobb's excellent gallery here. maybe i am too easily impressed, not having seen enough people's portfolios, but most of these work for me.
    Last edited by night86mare; 15th November 2008 at 02:20 PM.

  8. #8

    Default Re: Perception of light and illumination in practice

    Most art directors and creative directors I am working or have worked with are very nitpicking about the way we light and illuminate our set or the product to be photographed. Not surprisingly, most of them are trained in visual arts.

    To quote examples, if you still keep a copy of the Sony "Be Merry!" catalogue, turn to pages 21, 23 and 24. My studio created those images. Notice how the "hierarchy of light" is kept. It took us minimum 4 hours to light-up the set for each image. It was no mean feat to create some images to be use in a catalog that probably ended up in a rubbish bin anyway.

    Bear in mind that we are not discussing about light painting as night86mare had brought out in his previous post. That is beyond realm of light physics. Call me old-fashioned; I am a purist who firmly believe in how light should behave across an image plan.

    I do agree that Imran doesn't always follow the "hierarchy of light", but at least he manipulate his image beautifully, and with a sense of light direction in mind. Andrew's boat and storm image is a different story. Because common sense tells us the primary light source is from the distant sun and no where else! Where on good Mother Earth do you get a backlight in the middle of an ocean?

    My sincere apology to Andrew, if he is here to read my post. I don't mean to pick on you but how an image is illuminated tells us how well you understand light. In photography, understanding light is vital (as most of us know by now photography literally means 'light writing'). Besides the technical and creative aspects of this artform, understanding light falls between both. In other words, people who do not understand light can never be a great photographer. You can be very creative with lights but you lose the scientific aspects. Or, you are very scientific, but your images are thoroughly boring. Balancing both is to sustain an equilibrium of lighting and illumination in practice. Unfortunately, few photographers in the world can execute this to perfection.
    Last edited by photobum; 17th November 2008 at 07:35 AM.

  9. #9

    Default Re: Perception of light and illumination in practice

    i love the mood created by imran.
    seems to work for me all the time.

    but just a question (very noob qns actually).

    What is this hierarchy of light?
    tried to google it....landed me back to this thread....
    Canon 40D: 17 - 55 F2.8 : 70 - 2000 F4 IS : 50mm F1.4: 580EX Mk 1

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    Default Re: Perception of light and illumination in practice

    Well, take a look at this winner and the comments which followed. Perception of light can be highly subjective but the cake goes to this one. In fact, most of his photos and comments given proved that definition of a great photo can also be highly subjective. http://www.flickr.com/photos/henryleong/1346099311/
    Last edited by Kit; 17th November 2008 at 03:39 AM.

  11. #11

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by simplicitee View Post
    i love the mood created by imran.
    seems to work for me all the time.

    but just a question (very noob qns actually).

    What is this hierarchy of light?
    tried to google it....landed me back to this thread....
    sorry, it is my own coined term, i should copyright it.

    i meant that everything in the picture should be AS YOU SAW IT, in terms of luminance. i have seen pictures where the foreground is brighter than the sun (because of hdr)..

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    Default Re: Perception of light and illumination in practice

    For a landscape photographer in SG, no one is the master of light. The light is the master! LOL!! It has been a painful year waiting. When the light finally arrives, you are none prepared and always caught unnaware. Blistering barnacles.

    So night86mare has coined a new term which he will gleefully plaster all over CS' landscape photography for those HDR imageries. I kinda like that term. Sounds very hip. LOL!

    While I like how light is being played/portrayed/manipulated, it is still rather subjective to say which is the best. Still learning the art of lighting. If I could turn back time, I would have concentrated hard on my Geography lessons. Damn!

  13. #13

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by night86mare View Post
    sorry, it is my own coined term, i should copyright it.

    i meant that everything in the picture should be AS YOU SAW IT, in terms of luminance. i have seen pictures where the foreground is brighter than the sun (because of hdr)..
    Sry. I am also equally confuse by what you all mean that good photographers tend to keep hierarchy of light well.

    Pls explain to me as I wish to know more about this thing.

  14. #14

    Default Re: Perception of light and illumination in practice

    What they're talking about is unmotivated lighting affecting the quality of the photo -- wow factor etc. With hdr techniques photographers can do all this without resorting to actually lighting a scene.

  15. #15

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by shojibake View Post
    What they're talking about is unmotivated lighting affecting the quality of the photo -- wow factor etc. With hdr techniques photographers can do all this without resorting to actually lighting a scene.
    Is it using natural lighting to create those wow photos instead of resorting to HDR?

  16. #16

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by hazmee View Post
    So night86mare has coined a new term which he will gleefully plaster all over CS' landscape photography for those HDR imageries. I kinda like that term. Sounds very hip. LOL!
    glad you like it..
    Quote Originally Posted by Henessy View Post
    Sry. I am also equally confuse by what you all mean that good photographers tend to keep hierarchy of light well.

    Pls explain to me as I wish to know more about this thing.
    Quote Originally Posted by shojibake View Post
    What they're talking about is unmotivated lighting affecting the quality of the photo -- wow factor etc. With hdr techniques photographers can do all this without resorting to actually lighting a scene.
    actually, what i meant is simply what the phrase really means.

    hierarchy refers to the "predetermined order ranging from high to low". in real life, we have the brighest point - the highlights going to the darkest point - the shadows. each level of brightness has its own order, and we can see it and remember it, as well as do hdr/dri based on it, to replicate what we see.

    so that is what i call the hierarchy of light. the brightest point should remain the brighest point in the picture, and all the way down to the darkest point the order should be kept. a lot of hdr done on the web ignore all of this. they have bright foregrounds, where the brightness is as bright as the sun. seeing how the sun is really bright .. you have what i would call a radioactive foreground that is glowing. the hierarchy of light is lost. it's not really a very complex concept, i guess.

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    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by night86mare View Post
    so that is what i call the hierarchy of light. the brightest point should remain the brighest point in the picture, and all the way down to the darkest point the order should be kept.
    The conventional terminology for what you describe is that the luminance transfer function (characteristic curve) is monotonic. So-called local tone mapping operators use to reduce HDR image to lower DR output typically (possibly always, would have to think a bit more on the math) violate this assumption. In other words, the only acceptable manipulation to you is a global, monotonic tone-mapping operator, also known as "adjusting the curve".

  18. #18

    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by LittleWolf View Post
    The conventional terminology for what you describe is that the luminance transfer function (characteristic curve) is monotonic. So-called local tone mapping operators use to reduce HDR image to lower DR output typically (possibly always, would have to think a bit more on the math) violate this assumption. In other words, the only acceptable manipulation to you is a global, monotonic tone-mapping operator, also known as "adjusting the curve".
    your terminology is alien to me.

    can you put it in less technical terms? you sound like my statistics professor here (monotonic, gg)

    from what i gather, i'm not sure what you mean, but i think you're saying that hdr "compresses" the tonal range artificially. it matters not to me, so long as bright = bright, and dark = dark. when you end up having bright points dark and dark points bright (which is amazingly, what some people have wound up defining hdr as).. then something is wrong.
    Last edited by night86mare; 18th November 2008 at 08:51 PM.

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    Default Re: Perception of light and illumination in practice

    Quote Originally Posted by night86mare View Post
    your terminology is alien to me.
    Generally considered secondary/high school maths... consult Wikipedia.

    from what i gather, i'm not sure what you mean, but i think you're saying that hdr "compresses" the tonal range artificially. it matters not to me, so long as bright = bright, and dark = dark.
    What I am saying is that, if you require the order of "brighter than" or "darker than" to be preserved in your image, the only way to convert a high dynamic range image to a lower dynamic range image is to reduce the contrast, i.e. create a "flat" image. The so-called local tone-mapping operators used in HDR software (which is what most people mean when they talk about "HDR image") do not preserve the order of tonal values.

  20. #20

    Default Re: Perception of light and illumination in practice

    In the silver halide days, a version of applied sensitometry was invented by the photographer Ansel Adams. Called the "Zone System", this practice required the photographer to do several things, the most interesting of which were:

    • Determine precisely how your 'specific' film/meter/camera/processing/printing combination reproduces the light available to it.
    • Learn how to "previsualize" the final result from your own viewing of a scene, and the measurements of the scene you take with a light meter.

    This combination of sensitometry and visualization, properly applied, led Adams and many others to create some wonderful photographs from scenes that 'did not' create that first impression. HDR represents the digital-age equivalent of the Zone System. It pretty much eliminates limitations on capturing the full dynamic range of the light available from a scene.

    HDR, together with tone mapping, have very powerful ways to combine both the dark parts and the light parts of the scene, overcoming part of the dynamic range limitations of our cameras.
    Like all techniques, HDR can give stunning results. However, it can give questionable results that look, to some eyes, artificial or too painterly.

    Furthermore, mindless claims like “HDR increases the dynamic range of your photographs” are not true. HDR does nothing of that sort. What it does is to squeeze (compress) the dynamic range in the scene so that it fits into what your photograph can show.
    Last edited by photobum; 18th November 2008 at 11:54 PM.

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