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Thread: Exposure

  1. #21
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    Default Re: Exposure

    Quote Originally Posted by espn
    Psst.... it's school holidays.
    I wonder what advice he will give in the Seventh Month?!?

  2. #22
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    Default Re: Exposure

    Quote Originally Posted by Artosoft
    This is a good link. In particular, it correctly explains that "exposure" is a quantity unaffected by ISO film/sensor sensitivity. (The ISO sensitivity merely gives an indication what value a "desirable" exposure should take.)

    As for how to adjust the exposure, it is not a question of DSLR vs. any other camera. In particular, some DSLRs (notably from Olympus) do not allow you to make a concious decision about exposure in the first place as they are always in "fully automatic" mode and do not indicate the chosen exposure parameters.

  3. #23
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    Default Re: Exposure

    [(camera shutter speed x lens aperture) / camera ISO] + white balance => exposure
    __________________________________________________ ______________________

    : here (camera shutter speed x lens aperture) means:
    > isnt that when u choose a bigger aperture, u can use a faster shutter speed?
    > there must be a balance between this aperture and shutter speed.
    > if u use a too low shutter speed for correct aperture, u will never have a good expo.
    > for an example, F2.8@ 1/250 = F4 @ 1/125 = F5.6 @ 1/60 = F8 @ 1/30
    __________________________________________________ ______________________
    aperture or f-stop as we all know determine the diameter
    of the final len element that allows how much light to pass thru.
    f-stop will also determine how much focus will be in front of subject
    and behind the subject. f11 will almost have everything u
    see sharp. f2.8 will only have the subject very sharp,
    the rest (in front and behind, very blur)

    ____________________________________
    f-stop: 2.8 shutter speed: 1/250 sec
    let say this is the "correct settings" for my picture of a tulip field in a sunny day.

    2.8 * 1/250 = this will give you the relative SIZE of the
    iris diaphragms in the len at that moment of shutter press.

    ____________________________________
    when u change that shutter speed to say, 1/300 {2.8 x 1/300 = 0.0093}
    now that the relative size
    of iris will be even smaller =
    resulting in underexposed photo.
    ____________________________________
    when u change that shutter speed to say, 1/125 {2.8 x 1/125 = 0.0224}
    now this will make the relative size of
    iris bigger (aperture is seemed to be bigger)
    needless to say, this will give an overexposed photo.
    __________________________________________________ ______________________

    next, [(camera shutter speed x lens aperture) / camera ISO]

    The camera ISO rating (film speed) will determine the
    resulting exposure also. each increment in ISO value relates to
    a doubling of the sensitivity to light.
    A film's sensitivity is known as its ' speed' and
    is expressed as an ASA/ISO number.
    The higher the number the more sensitive it is and
    consequently the less light it needs to form an image.
    The lower the number the less sensitive it is and the
    more light it will require. a higher ISO will allow usage
    of faster shutter speed as well.

    __________________________________________________ ______________________
    [(camera shutter speed x lens aperture) / camera ISO] + white balance = exposure

    white balance is part of the final exposure.
    this is personal preference to use what kind of color temp,
    for your final exposure. this is where color tone control
    comes into play. some prefer warm some cold.
    individual preference is all i can say.

  4. #24
    Senior Member +evenstar's Avatar
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    Default Re: Exposure

    think of it in this way:

    you have a tap and a sponge. To make the sponge fully soaked, you have to turn on the tap (obviously). If the tap is turned on at max, the sponge takes a shorter time to fill, and vice versa. Similarly, a more absorbent sponge will take a shorter time to get soaked, and vice versa.

    In photography, the tap is your lens, and the sponge is your sensor. For a particular scene, opening up the aperture will allow you to use a faster shutter speed, and stopping down will require a longer shutter speed. Increasing the ISO will allow you to use a faster shutter speed as well.

    anyway, there is no right or wrong exposure. as long as the picture is what you intended, the exposure is correct.
    eat. drink. shoot

  5. #25
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    Default Re: Exposure

    it is also like you reached a river and u trying to use your hand to hold some amount of water. how wide u open your hand is the aperture. how fast you want go grab the water is the shutter speed. the river itself is the amount of light u want to capture. it doesnt matter how much more water your hand has [overexposed/underexposed] , because everyone has different "thirst"

  6. #26
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    Default Re: Exposure

    This is good, pity I'm not the one making all these crap, else sure kena lock + the posts removed very fast...

    Keep going, school holidays don't last forever.

  7. #27
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    Default Re: Exposure

    Quote Originally Posted by ronaldjace
    [(camera shutter speed x lens aperture) / camera ISO] + white balance => exposure
    __________________________________________________ ______________________

    : here (camera shutter speed x lens aperture) means:
    > isnt that when u choose a bigger aperture, u can use a faster shutter speed?
    > there must be a balance between this aperture and shutter speed.
    > if u use a too low shutter speed for correct aperture, u will never have a good expo.
    > for an example, F2.8@ 1/250 = F4 @ 1/125 = F5.6 @ 1/60 = F8 @ 1/30
    __________________________________________________ ______________________
    aperture or f-stop as we all know determine the diameter
    of the final len element that allows how much light to pass thru.
    f-stop will also determine how much focus will be in front of subject
    and behind the subject. f11 will almost have everything u
    see sharp. f2.8 will only have the subject very sharp,
    the rest (in front and behind, very blur)

    ____________________________________
    f-stop: 2.8 shutter speed: 1/250 sec
    let say this is the "correct settings" for my picture of a tulip field in a sunny day.

    2.8 * 1/250 = this will give you the relative SIZE of the
    iris diaphragms in the len at that moment of shutter press.

    ____________________________________
    when u change that shutter speed to say, 1/300 {2.8 x 1/300 = 0.0093}
    now that the relative size
    of iris will be even smaller =
    resulting in underexposed photo.
    ____________________________________
    when u change that shutter speed to say, 1/125 {2.8 x 1/125 = 0.0224}
    now this will make the relative size of
    iris bigger (aperture is seemed to be bigger)
    needless to say, this will give an overexposed photo.
    __________________________________________________ ______________________

    next, [(camera shutter speed x lens aperture) / camera ISO]

    The camera ISO rating (film speed) will determine the
    resulting exposure also. each increment in ISO value relates to
    a doubling of the sensitivity to light.
    A film's sensitivity is known as its ' speed' and
    is expressed as an ASA/ISO number.
    The higher the number the more sensitive it is and
    consequently the less light it needs to form an image.
    The lower the number the less sensitive it is and the
    more light it will require. a higher ISO will allow usage
    of faster shutter speed as well.

    __________________________________________________ ______________________
    [(camera shutter speed x lens aperture) / camera ISO] + white balance = exposure

    white balance is part of the final exposure.
    this is personal preference to use what kind of color temp,
    for your final exposure. this is where color tone control
    comes into play. some prefer warm some cold.
    individual preference is all i can say.
    excellent cut-and-paste from various sources.... pity the lack of understanding.

    i suggest u go to the library and pick up byran peterson's "understanding exposure" and read it for the remainder of the school holidays.... b4 some folks here die of laughter.

    as +evenstar aptly put, there's no such thing as a "correct" exposure. think abt it.
    If Life worked on auto mode then manual mode for photography would have never existed.” ― Deeksha Mittal

  8. #28
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    Default Re: Exposure

    Quote Originally Posted by nightwolf75
    excellent cut-and-paste from various sources.... pity the lack of understanding.

    i suggest u go to the library and pick up byran peterson's "understanding exposure" and read it for the remainder of the school holidays.... b4 some folks here die of laughter.

    as +evenstar aptly put, there's no such thing as a "correct" exposure. think abt it.
    You've got it.

    Just similar to an overzealous-brainless-mindless-zealot that I know who's trying desperately to edge me into a war

  9. #29
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    Default Re: Exposure

    Quote Originally Posted by nightwolf75
    excellent cut-and-paste from various sources.... pity the lack of understanding.

    i suggest u go to the library and pick up byran peterson's "understanding exposure" and read it for the remainder of the school holidays.... b4 some folks here die of laughter.
    Hi nightwolf75,

    Thanks for speaking up my mind.

    To me, those calculation and absolute numbers/answers that are obtained from the "formula" really means nothing from engineering and photography standpoint.

    For the sake of the TS, maybe can try to follow this article to explain about photography.
    莫问前程有愧,只求今生无悔. Time pasts, Places changed, Beauty faded, what is left are Photos of Memories…

  10. #30
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    Default Re: Exposure

    Quote Originally Posted by Francis247
    Hi nightwolf75,

    Thanks for speaking up my mind.

    To me, those calculation and absolute numbers/answers that are obtained from the "formula" really means nothing from engineering and photography standpoint.

    For the sake of the TS, maybe can try to follow this article to explain about photography.
    I'd go with the book nw75 recommended

  11. #31
    Moderator Francis247's Avatar
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    Default Re: Exposure

    Quote Originally Posted by espn
    I'd go with the book nw75 recommended
    Yap, agree with you.

    Another book that I will recommend is
    Understanding Digital Photography by Bryan Peterson
    莫问前程有愧,只求今生无悔. Time pasts, Places changed, Beauty faded, what is left are Photos of Memories…

  12. #32
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    Default Re: Exposure

    what you mean i lacking of understanding? because if i am only just a starter, you old bird can say anything - i dont give a damn. i just wrote that long post earlier to show how would that equation would be like, that's all. that is to say i never assumed anyhow. if u look deep enough, the equation is logically correct, as i already said my reasoning earlier.

    i do however respect espn for his vast knowledge/experience. that's for sure.

  13. #33
    Senior Member +evenstar's Avatar
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    Default Re: Exposure

    Quote Originally Posted by nightwolf75
    excellent cut-and-paste from various sources.... pity the lack of understanding.

    i suggest u go to the library and pick up byran peterson's "understanding exposure" and read it for the remainder of the school holidays.... b4 some folks here die of laughter.
    i would like to see which photographer goes out to the field with a calculator and starts making all the calculations based on the formula..


    jokes aside..i usually use the sunny 16 rule outdoors, and once u get used to it, u can roughly gauge the exposure setting outdoors without having to trial and error too much
    eat. drink. shoot

  14. #34
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    Default Re: Exposure

    Quote Originally Posted by ronaldjace
    what you mean i lacking of understanding? because if i am only just a starter, you old bird can say anything - i dont give a damn. i just wrote that long post earlier to show how would that equation would be like, that's all. that is to say i never assumed anyhow. if u look deep enough, the equation is logically correct, as i already said my reasoning earlier.

    i do however respect espn for his vast knowledge/experience. that's for sure.
    You lack understanding because of c&p'ing with no explanation. What is the correct exposure? Read the book ESPN has mentioned a countless number of times, it really does help.

  15. #35
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    Default Re: Exposure

    1) i never never said anyone would do calculations. i never even said anyone would need a calculator.

    2) it was just a simple summary , IT IS NOT A FORMULA TO USE.

    3) sorry to have offended anyone if i had. dint meant that at all.

  16. #36
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    Default Re: Exposure

    Actually that book that was mentioned is a very hot book. Always seem to be on-loan out from the library.

    espn, know anybody that owns the book? so i can borrow and read while i'm sitting on the toiletbowl every morning.

  17. #37
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    Default Re: Exposure

    Quote Originally Posted by ronaldjace
    [(camera shutter speed x lens aperture) / camera ISO] + white balance => exposure
    Hi ronaldjace,

    Could you enlighten me the above ?

    Till now my understanding of exposure formula as

    EV = log2(aperture2 x (1/shutter speed) x (ISO sensitivity/100))

    but yours seem to be

    [(camera shutter speed x lens aperture) / camera ISO] + white balance => exposure

    How did the white balance contribute to the exposure computation ?

    Shouldn't white balance is meant for controlling the colour cast ?

    Regards
    寒冰不能斷流水 枯木亦會再逢春

  18. #38
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    Default Re: Exposure

    Quote Originally Posted by DarkForce
    Hi ronaldjace,

    Could you enlighten me the above ?

    Till now my understanding of exposure formula as

    EV = log2(aperture2 x (1/shutter speed) x (ISO sensitivity/100))

    but yours seem to be

    [(camera shutter speed x lens aperture) / camera ISO] + white balance => exposure

    How did the white balance contribute to the exposure computation ?

    Shouldn't white balance is meant for controlling the colour cast ?

    Regards

    Chris, long time no see. don't worry about the formula go and shoot more bugs

  19. #39

    Default Re: Exposure

    Quote Originally Posted by DarkForce
    Hi ronaldjace,

    Could you enlighten me the above ?

    Till now my understanding of exposure formula as

    EV = log2(aperture2 x (1/shutter speed) x (ISO sensitivity/100))

    but yours seem to be

    [(camera shutter speed x lens aperture) / camera ISO] + white balance => exposure

    How did the white balance contribute to the exposure computation ?

    Shouldn't white balance is meant for controlling the colour cast ?

    Regards
    Do they actually teach this in a photography degree course? If so I may want to reconsider studying it Not really what I had in mind.
    My Personal Folio (of random events and things)

  20. #40
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    Default Re: Exposure

    some of the best shooters out there are self-taught...

    for all things creative, i've never thought much of formal courses.

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