very newbie question

Discussion in 'Photography Beginners' Forum' started by StreetShark, Mar 22, 2007.

  1. StreetShark

    StreetShark TPF Noob!

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    Well I know what aperture is and how it works, I know ISO and I know lens speed but the term exposure confuses me. Its just used so much I can't seem to understand what some one means when they say exposure. Please explain to me what it is.
     
  2. dewey

    dewey TPF Noob!

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  3. StreetShark

    StreetShark TPF Noob!

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    Ok so basically exposure is it all put to gether to determine how light or dark the picture is?
     
  4. sdgmusic

    sdgmusic TPF Noob!

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    sort of. I believe, in my terms, it is the amount of light that the "film" is "exposed" to. this is controlled by the aperture size and amount of time the shutter is open for.
     
  5. hazzayoungn

    hazzayoungn TPF Noob!

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    i have a metaphor, its a bit silly...and you gotta neglect the iso for a bit...

    imagine its the day after thanksgiving and a crowd of people has gathered outside target. the employees open the doors fully and people start mobbing in for an amount of time. they then close the doors...because they can. the store depending on how fast the people came in will either be overcapacity, at capacity or undercapacity. likewise, if you set your aperture and open the shutter, depending on how long you keep it open, it will be overexposed, perfectly exposed, or underexposed.

    now lets say they open the doors halfway so half the people get in per minute. it will take twice as long for the same amount of people to get in. if they had the door at 1/4 the size as the original, it will take 4 times as long to get the same amount of people in. likewise, if you use an aperture half the size(1 stop), youll need a shutter speed twice as long (also 1 stop)

    now for the iso. for some reason, EVERYBODY needs something to hold their merchandise, and theyre only alloted one per person. if only baskets are available, then more people will be able to fit in. if only carts are available, then less people will be able to get in. likewise, if you use a finegrain low iso film (the baskets) more light can come in. if you use a non-fine grain high iso film(the carts), less light can come in

    im not exactly sure i answered your question...but i hope that helps a bit
     
  6. Garbz

    Garbz No longer a newbie, moving up!

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    I think of it in terms of the science. Film picks up light. The more light the brighter it gets till it hits it's maximum (clear slide, or brown negative). Now the film needs to be exposed to a certain amount of light.

    Increasing the film speed reduces the amount of light it needs to be exposed to. Increasing the aperature or reducing the shutter speed increases the exposure (as in time). Likewise reducing the aperature or speeding up the shutter reduces the exposure.
     

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