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Thread: How to achieve a lower ISO?

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    Default How to achieve a lower ISO?

    I have a Canon 7D and the lowest ISO offered is 100. I would like to have it lower for blurred images, i.e. as water. I have never used neutral density filters. Would they achieve this? Something else? I mainly use the Canon 400 f4 DO and the Canon 70-200 f2.8 and I just acquired the Canon EF 10-22. Does each lens need a different solution/piece of equipment?

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    As Peter said, using a Neutral Density filter will achieve your goal of blurred images since it reduces the amount of light.

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    BPN Viewer Charles Glatzer's Avatar
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    Nancy,

    Each lens may require a different filter size. You can purchase rectangular filters and a holder with different sized filter rings to negate having to purchase different sized filters for lenses. The 400 DO will require a specialized drop-in holder and 52mm filter.

    Chas

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    Another approach is simply wait til sunset, before sunrise, or a good overcast. As a matter of fact, when I'm out shooting and I loose enough light for regular photography (getting too late in the day for example) I switch to motion blur capture time. Of course decreasing your aperture to like F22 can help, and neutral density filters don't need anything fancy, just hold a square one in front of the lens and shoot. regards~Bill

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    Hi Nancy,

    Charles is right about the 400 f/4 DO needing a 52mm drop in filter, but the other two both take the same 77mm sized screw-in filter so you could share one filter (either a Neutral Density or Polarizer) between both the 10-22 and 70-200 f/2.8.

    A polarizer will eat 1.5 to 2 stops of light and ND filters are commonly available in 1, 2, 3, 6 and 10 stops of light reduction. The strength of ND filter you need depends on what motion blur effect you are trying to achieve, and in what light conditions, but a 3 stop one is probably the best for general use.

    Hope this helps,

    Julian.

    Quote Originally Posted by Charles Glatzer View Post
    Nancy,

    Each lens may require a different filter size. You can purchase rectangular filters and a holder with different sized filter rings to negate having to purchase different sized filters for lenses. The 400 DO will require a specialized drop-in holder and 52mm filter.

    Chas

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    I think a 3 stop should work too. If you shoot in full sun and use the sunny 16 rule you could start with f16, iso 100 and 1/100 sec. Add the 3 stops loss ND and now you are down to 1/12 sec which can give a nice blur on water.

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    BPN Viewer Charles Glatzer's Avatar
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    Quote Originally Posted by Doug Schurman View Post
    I think a 3 stop should work too. If you shoot in full sun and use the sunny 16 rule you could start with f16, iso 100 and 1/100 sec. Add the 3 stops loss ND and now you are down to 1/12 sec which can give a nice blur on water.
    Doug,

    Way to work the numbers ;)

    Best,

    Chas

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    Emil Martinec
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    You could also take several images and stack them in Photoshop. Eight images stacked is equivalent to the effect of a 3 stop ND filter if the scene is sufficiently static, since the total shutter time is a factor of eight longer.

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    BPN Viewer Charles Glatzer's Avatar
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    Quote Originally Posted by Emil Martinec View Post
    You could also take several images and stack them in Photoshop. Eight images stacked is equivalent to the effect of a 3 stop ND filter if the scene is sufficiently static, since the total shutter time is a factor of eight longer.
    Emil,

    The exposure will be the same, but I am not sure the water will have the desired effect.
    Then again...I have seen some amazing soft water images taken with multiple exposures via Nikon.

    Best,

    Chas
    Last edited by Charles Glatzer; 12-08-2010 at 11:07 PM.

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    Thank you everyone for your advice and suggestions.

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    Roman Kurywczak
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    Hey Nancy,
    You will get debate on this......but I love my Singh Ray Vari ND filter! If you buy the 77mm size in the thin mount.......it will fit most of your lenses....and step down rings wile fit all of your lenses. This is the most versatile filter IMO......it has its issues......but still a great asset to the toolbox!

  12. #12
    WillRogers
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    Hi Nancy

    as the others have said, an ND (Neutral Density) Filter is the best option, however when I used a 3 stop ND filter, at F/16 and ISO 100, my camera didn't blur water enough as the shutter speed was still 1/10th of a second, whereas my friends 10 stop ND filter blurred water best...
    for waterfalls, 1/10th would have been fine, but I was trying to blur water travelling through a rocky section of a stream... so it can depend on your situtation and how 'silky' you want the water to look...

    my vote is for 3 stops as a minimum

    Will

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