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Thread: Cokin type third party filters

  1. #41
    Moderator daredevil123's Avatar
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    Default Re: Cokin type third party filters

    Quote Originally Posted by Octarine View Post
    Don't use decimal fraction.
    ND2 halves the amount of light. Therefore the calculation is 1/60 / 1/2 = 1/30. This, converted into a decimal fraction, is 0.03.
    ND2.. the 2 is the attenuation factor. Just multiply the shutter speed by the attenuation factor and you are done.

    1/60s exposure without filter:
    ND2 shutter speed = 1/60 * 2 = 1/30s
    ND4 shutter speed = 1/60 * 4 = 1/15s
    ND8 shutter speed = 1/60 * 8 = 1/7.5s round up to 1/8s
    ND400 shutter speed = 1/60 * 400 = 6.667s around up to 7 seconds
    assuming ISO and aperture stays constant.

    That is the simple way to calculate.
    If you want to think of stops, then each addition stop of ND will extend shutter speed by a factor of 2 (double the exposure time). So you have:
    ND2 = 1 stop ND, double the exposure time
    ND4 = 2 stop ND, twice double the exposure time 2^2 = 4 times
    ND8 = 3 stops ND, three times double the exposure time = 2^3 = 8 times.
    You will realize the calculation is already stated in the attenuation factor...
    Last edited by daredevil123; 11th July 2016 at 02:53 PM.

  2. #42
    Moderator Octarine's Avatar
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    Default Re: Cokin type third party filters

    Quote Originally Posted by romeo tango View Post
    I check my camera this morning and discovered that I can set the EV to 1, 1/3 or 1/2. It is currently set at EV1 so from 1/60s, 1 click brings me to 1/30.
    So can I say that the table you provided is EV1 stop ?
    Stop, EV settings are a different story. They do something similar, in the end. But adjusting shutter for ND filter usage is a 'manual EV' that it techncially not related to the click settings for in-camera EV.
    Since the click setting can be changed and I have seen dials that cause settings to 'jump' due to contact issues I would not recommend counting clicks. Check the display, do the simple Maths.
    EOS

  3. #43

    Default Re: Cokin type third party filters

    Quote Originally Posted by daredevil123 View Post
    ND2.. the 2 is the attenuation factor. Just multiply the shutter speed by the attenuation factor and you are done.

    1/60s exposure without filter:
    ND2 shutter speed = 1/60 * 2 = 1/30s
    ND4 shutter speed = 1/60 * 4 = 1/15s
    ND8 shutter speed = 1/60 * 8 = 1/7.5s round up to 1/8s
    ND400 shutter speed = 1/60 * 400 = 6.667s around up to 7 seconds
    assuming ISO and aperture stays constant.

    That is the simple way to calculate.
    If you want to think of stops, then each addition stop of ND will extend shutter speed by a factor of 2 (double the exposure time). So you have:
    ND2 = 1 stop ND, double the exposure time
    ND4 = 2 stop ND, twice double the exposure time 2^2 = 4 times
    ND8 = 3 stops ND, three times double the exposure time = 2^3 = 8 times.
    You will realize the calculation is already stated in the attenuation factor...
    Hi daredevil123,

    Thank you so much for your patience in typing the above details. Really appreciate that
    Tangfolio, 9mm; CZ75 Shadow, 9mm; S&W 686, .38

  4. #44

    Default Re: Cokin type third party filters

    Quote Originally Posted by Octarine View Post
    Stop, EV settings are a different story. They do something similar, in the end. But adjusting shutter for ND filter usage is a 'manual EV' that it techncially not related to the click settings for in-camera EV.
    Since the click setting can be changed and I have seen dials that cause settings to 'jump' due to contact issues I would not recommend counting clicks. Check the display, do the simple Maths.
    Hi Octarine,

    Thank you for your patience too. Really appreciate it
    Tangfolio, 9mm; CZ75 Shadow, 9mm; S&W 686, .38

  5. #45

    Default Re: Cokin type third party filters

    Hi all,

    Thank you guys so much for your patience and guidance

    I think for the time being, I will stick to the ND calculator apps while trying to understand the formulae
    Tangfolio, 9mm; CZ75 Shadow, 9mm; S&W 686, .38

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