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Thread: Can I not use a ND filter and cheat by using aperture?

  1. #1
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    Question Can I not use a ND filter and cheat by using aperture?

    Hi, I'm just trying to understand the physics of an ND filter, personally I do own a ND4 for my 18-55mm which I really bought just to mess around (The filter of course, not the lens).

    I understand that a ND filter is supposed to reduce the incoming wavelengths of light reaching the sensor equally. However is not the purpose of a narrow high number aperture supposed to also perform the same task just with blades instead? Of course I understand that aperture cant perform the same amount of light reduction that a high ND filter such as a ND400 filter can achieve. So really my question is, are low ND filters worth it since it seems most dslr apertures can actually duplicate the reduction capabilities of low ND filters?

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    Default Re: Can I not use a ND filter and cheat by using aperture?

    when you stop down your aperture, it also increase your depth of field. If you want to use a f1.4 lens wide open in bright sunlight, a ND filter would be useful.

  3. #3

    Default Re: Can I not use a ND filter and cheat by using aperture?

    Quote Originally Posted by dark_fusion View Post
    Hi, I'm just trying to understand the physics of an ND filter, personally I do own a ND4 for my 18-55mm which I really bought just to mess around (The filter of course, not the lens).

    I understand that a ND filter is supposed to reduce the incoming wavelengths of light reaching the sensor equally. However is not the purpose of a narrow high number aperture supposed to also perform the same task just with blades instead? Of course I understand that aperture cant perform the same amount of light reduction that a high ND filter such as a ND400 filter can achieve. So really my question is, are low ND filters worth it since it seems most dslr apertures can actually duplicate the reduction capabilities of low ND filters?
    can if u do nt want the shallow dof...n at smaller aperture(abv f11) diffraction may occur(IIRC)....
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    Default Re: Can I not use a ND filter and cheat by using aperture?

    Quote Originally Posted by dark_fusion View Post
    Hi, I'm just trying to understand the physics of an ND filter, personally I do own a ND4 for my 18-55mm which I really bought just to mess around (The filter of course, not the lens).

    I understand that a ND filter is supposed to reduce the incoming wavelengths of light reaching the sensor equally. However is not the purpose of a narrow high number aperture supposed to also perform the same task just with blades instead? Of course I understand that aperture cant perform the same amount of light reduction that a high ND filter such as a ND400 filter can achieve. So really my question is, are low ND filters worth it since it seems most dslr apertures can actually duplicate the reduction capabilities of low ND filters?
    I think the proper is "ND filter is supposed to reduce the intensity of light reaching the sensor equally".

    Regards,
    Arto.

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    Default Re: Can I not use a ND filter and cheat by using aperture?

    If you take long exposure like water fall, the ND will reduce the amount of light hence giving a smoother effect on the waterfall. too fast a shutter wil freeze it otherwise and its not easy to photoshop that effect.

  6. #6

    Default Re: Can I not use a ND filter and cheat by using aperture?

    Quote Originally Posted by dark_fusion View Post
    Hi, I'm just trying to understand the physics of an ND filter, personally I do own a ND4 for my 18-55mm which I really bought just to mess around (The filter of course, not the lens).

    I understand that a ND filter is supposed to reduce the incoming wavelengths of light reaching the sensor equally. However is not the purpose of a narrow high number aperture supposed to also perform the same task just with blades instead? Of course I understand that aperture cant perform the same amount of light reduction that a high ND filter such as a ND400 filter can achieve. So really my question is, are low ND filters worth it since it seems most dslr apertures can actually duplicate the reduction capabilities of low ND filters?
    You use ND only when you want to reduce the amount of light and at the same time stay within the shutter speed, aperture or sometimes (although rarely in digital) ISO you required to achieve the desired effects.

    There are times that you want slow shutter speeds to cause a blurring effect of moving objects. Sometimes, you want a large apperture to limit the DOF, but maximum shutter speed is not enough to cut the amount of light. You use ND filters in those situation.

    BC

  7. #7

    Default Re: Can I not use a ND filter and cheat by using aperture?

    ND filter is useful for the following:

    - when you are taking long exposure

    Incident 1
    You are taking waterfall photos, meter settings as f22, 1sec , ISO 100. With a ND4 filter, you can get 4sec exposure. This will produce more smoother and silky water effect.

    Incident 2
    You are taking cross road junction photos, meter settings as f22, 1/30sec , ISO 100. With a ND4 filter, you can get 1/8sec. This will achieve motion effect on the vehicles.

    - when you are taking big aperture outdoor

    Incident 1
    You are taking model photos, meter settings as f2.8 (you want this aperture for shallow DOF), 1/4000sec , ISO 100 and get 1 or 2 stops overexposure due to very hot weather. With a ND4 filter, you will get correct exposure.
    Last edited by megaweb; 13th February 2007 at 10:38 AM.
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    Default Re: Can I not use a ND filter and cheat by using aperture?

    To sum up, you basically need to use the ND filter if:-

    - you want to use bigger aperture for selective focus; and
    - you want to use slower shutter speed for some reasons; and
    - you cannot bring down your ISO anymore.

    Another example for such a use for it is when you need to balance flash with daylight.

    Typically if you're using a focal plane shutter, the sync speed is limited to 1/250 or less. And if the ambient light is too bright that your metering for ambient light goes to something like 1/1000, f/2.8 (you want to use this aperture for selective focusing like what megaweb described), and your ISO is already rock bottom at ISO100, then you can use ND4 to bring the shutter speed down to 1/250 and you can use fill-in flash with no problem. But don't forget to add in the ND factor for your flash calculations if you're not using TTL.
    Last edited by lsisaxon; 13th February 2007 at 10:16 AM.

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    Default Re: Can I not use a ND filter and cheat by using aperture?

    Quote Originally Posted by megaweb View Post
    ND filter is useful for the following:

    - when you are taking long exposure

    Incident 1
    You are taking waterfall photos, meter settings as f22, 1sec , ISO 100. With a ND4 filter, you can get 4sec exposure. This will product more smoother and silky water effect.

    Incident 2
    You are taking cross road junction photos, meter settings as f22, 1/30sec , ISO 100. With a ND4 filter, you can get 1/8sec. This will achieve motion effect on the vehicles.

    - when you are taking big aperture outdoor

    Incident 1
    You are taking model photos, meter settings as f2.8 (you want this aperture for shallow DOF), 1/4000sec , ISO 100 and get 1 or 2 stops overexposure due to very hot weather. With a ND4 filter, you will get correct exposure.
    Hurray..!

    Old school thought..A ND filter (be it 2, 4 or 6 stops has its intentions). Just as what megaweb has pointed out and I have to agree..

    Well, I prefer a picture that comes out straight from the camera. Isn't that what a photographer wanted it to be...:dunno:

    Of course, there may be instances where clients & situations required some degree of post processing/manipulation to "bring out certain effect/mood" of an image representation..Again, this, "may not be acceptable" in journalism works.

    The use of filters, gels, film types etc. were very common in film photography; and it is still with digital photography. I have encountered many film & digital users and there still carry many types of filters with them. Filters, film etc are tools/equipment of a photographer and some have put on their boxing gloves to challenge that so is the manipulation of a photo/image..This I will not elaborate to avoid any "flaming and shooting" at ourselves..

    Too much photo manipulations is kinda towards "graphic designing" than the art of photography. Anyway, digital photography is still photography, it all starts with an image and your connection to that image.. Just my 2 cents worth..

    So, a ND filter for you to mess around is a good start to understanding the usage of such an invention. It is not whether you can or canonot use a ND filter, or you whether you want or do not want etc.. remember you are the photographer that makes that image.. Have fun.

  10. #10
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    Default Re: Can I not use a ND filter and cheat by using aperture?

    Quote Originally Posted by megaweb View Post
    ND filter is useful for the following:

    - when you are taking long exposure

    Incident 1
    You are taking waterfall photos, meter settings as f22, 1sec , ISO 100. With a ND4 filter, you can get 4sec exposure. This will produce more smoother and silky water effect.

    Incident 2
    You are taking cross road junction photos, meter settings as f22, 1/30sec , ISO 100. With a ND4 filter, you can get 1/8sec. This will achieve motion effect on the vehicles.

    - when you are taking big aperture outdoor

    Incident 1
    You are taking model photos, meter settings as f2.8 (you want this aperture for shallow DOF), 1/4000sec , ISO 100 and get 1 or 2 stops overexposure due to very hot weather. With a ND4 filter, you will get correct exposure.
    Ooh thanks everyone Kinda forgot abt the DOF issues :x

    Hmm I havent tried out my ND4 in daylight settings with moving subjects yet, been using it mainly for getting those silky effects on water falls heh. Though the thing is the silky effect kinda looks the same whether its f22 4sec or f22 ND4 4sec

    Think I need to try out my ND4 in more situations, and maybe get a myself a grad ND or ND400
    Last edited by dark_fusion; 13th February 2007 at 01:21 PM.

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