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  1. #1
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    Variable Neutral Density

    I bought a variable neutral density filter here in OKC, and now I am wondering if I made a wise purchase. I am now shooting in RAW, and I use Photoshop Elements 10. With that in mind, is it even necessary for me to raise and lower exposure with this filter since I can do that in PS 10? I am planning to shoot in manual mode, then raise and lower exposure with the filter. Is this over-kill? I can already bracket exposure using my D90 camera. Is there an advantage to altering exposure and leaving the f-stop and shutter speed fixed? Please advise.

  2. #2
    Panarus biarmicus Moderator (Sports) SmartWombat's Avatar
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    Re: Variable Neutral Density

    Not leaving it alone, but using it to allow slow shutter speed in bright light.
    That's what a ND filter is for.

    It allows you to expose correctly (not under-or over-expose) and use a slower shutter speed to blur moving subjects in bright light.
    PAul

    Scroll down to the Sports Forum and post your sports pictures !

  3. #3
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    Re: Variable Neutral Density

    Hi Paul,

    The reason that most folks implement an ND filter is so they can slow their shutter speed down (when there is an abundance of light) to create a specific look to their photos; mostly in landscape photography.
    The first thing that comes to mind is lowering your shutter speed enough to blur the water flowing in a river; over a rock or even over a water fall.

  4. #4
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    Re: Variable Neutral Density

    If I read this right you purchased a graduated ND filter, light on one end and dark on the other. Best used to bring high EV elements like sky into balance with dark foreground elements. Yes you can do this in PS, but what happens if you've completely blown the highlights beyond usable recovery? Likewise you've so heavily underexposed the foreground to get the brights that there is no detail to recover. Getting it right in camera has always been always better then trying to fix it later. There will be some situations that PS will not fix.

    Now many digitals don't set ISO below 100/200 and a full ND is useful to make exposures below that rating.

    It's another tool to understand and use as needed.
    It's not about the camera....

  5. #5
    Be serious Franglais's Avatar
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    Re: Variable Neutral Density

    I do not understand what you mean by "Is there an advantage to altering exposure and leaving the f-stop and shutter speed fixed?"

    My understanding:

    - You have bought a progressive neutral density filter
    - You want to use it (for example) to darken the overexposed sky on a landscape with the dark part of the filter but leaving the foreground unchanged with the transparent part of the filter

    Most people nowadays do this without a filter by doing multiple identical images at different exposures (bracketing) and using HDR software to produce a combined image.

    You could probably do almost the same from a single image shot in RAW, adjust the exposure to produce three different images which you then combined with HDR software to make the combined image.
    Charles

    Nikon D800, D7200, Sony RX100m3
    Not buying any more gear this year. I hope

  6. #6
    Senior Shooter Greg McCary's Avatar
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    Re: Variable Neutral Density

    Charles is right but I am old school I am not good at HDRs. The grad filter will help Lightroom 4 is also a very good option. I expose more for the sky and bring the shadows up with Lightroom 4. LR4 also had grad filters in the software. But you have to have a good RAW file to start with. I have seen nothing that can fix blown out highlights.
    I am like Barney Fife, I have a gun but Andy makes me keep the bullet in my pocket..

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  7. #7
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    Re: Variable Neutral Density

    Charles: I have done a poor job of explaining the type of filter I purchased. With this filter, you turn the outer ring and the ENTIRE IMAGE is lightened or darkened depending which way you turn the ring. With this filter, if you turn the ring and darken the sky, you will also darken the foreground. If I am in apeture mode, and do bracketing, the shutter speed can give me a plus 1 or minus 1. If a bracket using my D90, then shoot the same scene in manual mode turning the ring on the ND filter will I see any difference?

  8. #8
    Woe is me! wfooshee's Avatar
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    Re: Variable Neutral Density

    The point of the ND filter is simply to require longer exposure then otherwise possible.

    If you run a shutter speed slow enough to get 2 stops of overexposure (slower shutter to get water motion or something,) then reduce the exposure in Photoshop, you may get a similar effect, but you may also have blown the bright areas beyond recovery.

    Shoot with an ND dark enough for two stops, shoot that same shutter speed, and you get the desired exposure in the camera, without risk of losing bright detail.

    Your question seems to be "Isn't it the same thing?" and theoreticlly, it is. But it's not.

    In theory, theory and practice are the same. In practice, they are not.

  9. #9
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    Re: Variable Neutral Density

    Thanks to EVERYONE for your help. PS: The comment about theory and practice was particularly insightful. I am thinking this logic may apply to other situations also (maybe not even photography).

  10. #10
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    Re: Variable Neutral Density

    Quote Originally Posted by Paul in OKC View Post
    Charles: I have done a poor job of explaining the type of filter I purchased. With this filter, you turn the outer ring and the ENTIRE IMAGE is lightened or darkened depending which way you turn the ring. With this filter, if you turn the ring and darken the sky, you will also darken the foreground. If I am in apeture mode, and do bracketing, the shutter speed can give me a plus 1 or minus 1. If a bracket using my D90, then shoot the same scene in manual mode turning the ring on the ND filter will I see any difference?
    This sounds like a polarizing filter not a neutral density. two very different filters.
    It's not about the camera....

  11. #11
    Woe is me! wfooshee's Avatar
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    Re: Variable Neutral Density

    It is a variable ND filter he's talking about. Two glass plates, you rotate the one to change the darkness. Polarization is how they work, thought. And they are quite expensive! Consider that you are putting two pieces of glass on the front of your lens; you'll wna them well-made enough to be optically perfect, and to not add any reflections.

    I've read of people making their own by mounting a circular polarizer, then stacking a linear polarizer. As the polarizers cross, you get less light, just like playing with polarized sunglass lenses.
    Last edited by wfooshee; 07-12-2012 at 08:25 PM.

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