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Thread: Relationship between shutter speed and aperture size

  1. #1

    Default Relationship between shutter speed and aperture size

    Hi guys. i need help. Need someone to explain to me clearly the relationship between shutter speed and aperture size. How it affect the pic. what is aperture pirority? how it help us? I've been using AF mode to often. would like to try manual since i'm playing with my Nikon f3 camera now.
    Last edited by Illidan; 20th November 2004 at 01:43 AM.

  2. #2

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    wat has AF(auto focus) got to do with aperture priority????

    basically shutter and aperture come together to give u certain values to a correct exposure...

    aperture priority is when u set the aperture and the camera chooses the best shutter speed for u to use... how it affects the pix...aperture affects it in a way called Depth of field...

    so if one changes...the other muz change the other way to compensate for this change...


    E.G f5.6 1/200 is the correct exposure
    u want an aperture of f2.8 so u have to make the shutter faster as more light is coming in thru the aperture now...

  3. #3
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    Exposure is determined by 3 things: shutter speed, aperture and iso value.

    All 3 must come together to give you the correct exposure for a given scene. Example:
    Correct exposure for a top lit subject on a sunny day using the Sunny 16 rule is f16, 1/125 using ISO100 film. This exposure value however, is also equivalent to f11 at 1/250, f8 at 1/500, f5.6 at 1/1000. These exposures all represent the same amount of light.

    Think of it as a tap filling a bucket. How big you open the tap is the how big your aperture is. For a given bucket (ie exposure for a given scene), if you fully open the tap, the time taken to fill the bucket is short (fast shutterspeed). If you close the tap to allow only a trickle to flow, you will take a long time to fill the bucket (slow shutterspeed). However, the amount of water in the bucket (amount of light hitting the sensor/film) is the same in both cases.

    Whether you want a big/small aperture with the corresponding fast/slow shutter speed depends then on the creative choices you make, ie how much Depth of Field you want, how much motion blur you want, etc.

    Aperture priority is a mode where you choose the aperture you want and the camera automatically assigns the correct shutterspeed to give you the correct exposure as dictated by the camera's meter.

  4. #4
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    Default Water & Tap

    Wow

    Great analogy - it made it clearer for me too.

    Thanks a lot.

    Cheers

  5. #5

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    as clear as water analogy. hurrah!!

  6. #6
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    Actually, there's still DOF not touched on yet... I believe megaweb has already explained the relation between the three, do a search

  7. #7

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    Quote Originally Posted by espn
    Actually, there's still DOF not touched on yet... I believe megaweb has already explained the relation between the three, do a search
    i think that, for the thread starter, it may be better to illustrate their relationship with only 2 factors for now and not to 'complicate' the relationship by introducing another factor or dimension.
    Last edited by reachme2003; 20th November 2004 at 11:36 AM.

  8. #8
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    Go shoot a roll and note down your shutter spd & aperture settings after each shot. Shoot as many variations as possible. You waste a roll & $$, but think of the learning material you get after that.

  9. #9
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    Aperture and shutter speed (and ISO) determine the amount of light required to get a correct exposure. If u set the camera to aperture priority mode (A mode), then u are supposed to set the camera aperture (and ISO) and the camera auto-meter system will determine the shutter speed for u.
    If u want to try manual metering (M mode), u need to remember the "Sunny-16" rule and start to practise on M mode.
    Simply speaking, the Sunny 16 rule, u choose a sunny day, and set the aperture to f16, and if u use ISO 100, u should set yr shutter to 1/100. Then u should get a correct exposure photo.
    U can then try to change the aperture, to 2 stop down, or 2 stop up, etc, and see the result in prints. U would get under exposed and over exposed photos.

  10. #10

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    very chiem(deep)! Austin, how was FHM finals?

  11. #11
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    Quote Originally Posted by reachme2003
    very chiem(deep)! Austin, how was FHM finals?
    Leen won!

  12. #12

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    Quote Originally Posted by Astin
    Leen won!
    hurray, hurray for Leen! so, we can see 'more' of her in FHM.

  13. #13

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    Quote Originally Posted by justarius
    Exposure is determined by 3 things: shutter speed, aperture and iso value.

    All 3 must come together to give you the correct exposure for a given scene. Example:
    Correct exposure for a top lit subject on a sunny day using the Sunny 16 rule is f16, 1/125 using ISO100 film. This exposure value however, is also equivalent to f11 at 1/250, f8 at 1/500, f5.6 at 1/1000. These exposures all represent the same amount of light.

    Think of it as a tap filling a bucket. How big you open the tap is the how big your aperture is. For a given bucket (ie exposure for a given scene), if you fully open the tap, the time taken to fill the bucket is short (fast shutterspeed). If you close the tap to allow only a trickle to flow, you will take a long time to fill the bucket (slow shutterspeed). However, the amount of water in the bucket (amount of light hitting the sensor/film) is the same in both cases.

    Whether you want a big/small aperture with the corresponding fast/slow shutter speed depends then on the creative choices you make, ie how much Depth of Field you want, how much motion blur you want, etc.

    Aperture priority is a mode where you choose the aperture you want and the camera automatically assigns the correct shutterspeed to give you the correct exposure as dictated by the camera's meter.


    Good , I like your explaination , is well said and clear !

  14. #14

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    Quote Originally Posted by Astin
    ....Simply speaking, the Sunny 16 rule, u choose a sunny day, and set the aperture to f16, and if u use ISO 100, u should set yr shutter to 1/100. Then u should get a correct exposure photo.
    U can then try to change the aperture, to 2 stop down, or 2 stop up, etc, and see the result in prints. U would get under exposed and over exposed photos.
    Still very new in these...So what should the values be if I were to say shoot at ISO 50 or ISO 200?

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    Quote Originally Posted by harmony
    Still very new in these...So what should the values be if I were to say shoot at ISO 50 or ISO 200?
    The shutterspeed should be 1/ISO value, so at ISO 50, the shutterspeed is 1/60, at ISO 200, the shutterspeed is 1/250. Note that the Sunny f16 rules only applies in bright sun (no clouds or haze), and works only for frontlit object (you have to modify the rule for toplighting, backlighting, sidelighting)

  16. #16

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    Quote Originally Posted by justarius
    The shutterspeed should be 1/ISO value, so at ISO 50, the shutterspeed is 1/60, at ISO 200, the shutterspeed is 1/250. Note that the Sunny f16 rules only applies in bright sun (no clouds or haze), and works only for frontlit object (you have to modify the rule for toplighting, backlighting, sidelighting)
    Thanks

  17. #17
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    You might want to check this site. I find it very usefull and very detail. It also covers sunny 16 rules.

    http://www.fredparker.com/ultexp1.htm

    If you find the explainations are too lengthty, then just print the 2 charts.

    Exposure Value Chart is a simple to under stand guide line (in a table fornat) that states the EV (simple way to explain is amount of light) in environment where the subject is under. The EV range covers from -6EV to 23EV.

    Exposure Factor Relationship Chart is a simple guide line (in tablle format) that show at different ISO with it respective EV, apertures values (range from f1.4 to f32) and the respective shuttle speed requires base on the EV.

    Now that you have gotten a EV using the guide lines from the Exposure Value Chart, you know the ISO value you are using, select the point in the Exposure Factor Relationship Chart, move horizontally across the chart, select the aperture that you want to use, it will tell you the required shuttle speed.

    To put it simply, the charts will show you the shuttle speed to use, base on the environment where the subject is under, the ISO of film / sensor you used / set, your intended aperture to use.

    Happy shooting.
    photography makes one sees things from all angles.

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