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Author Topic: Any recommendations of variable ND filters for motion work?  (Read 309 times)

Ellis Vener

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Any recommendations of variable ND filters for motion work?
« on: August 21, 2017, 07:35:59 PM »

A friend who shoots a lot of video has recommended the Lightcraft, Genus, and Schneider brands as all being well made and reasonable neutral.

Does anyone here have other recommendations?

Thanking you in advance,

Ellis
« Last Edit: August 21, 2017, 07:40:52 PM by Ellis Vener »
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Ellis Vener
http://www.ellisvener.com
Creating photographs for advertising, corporate and industrial clients since 1984.

Ellis Vener

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Re: Any recommendations of variable ND filters for motion work?
« Reply #1 on: August 21, 2017, 10:13:15 PM »

After doing a lot of online research, the winner is the Genustech POLARIZER ND Variable Filter https://www.genustech.tv/collections/polarizer-nd-variable-filter.
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Ellis Vener
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Creating photographs for advertising, corporate and industrial clients since 1984.

smthopr

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Re: Any recommendations of variable ND filters for motion work?
« Reply #2 on: August 24, 2017, 12:29:46 PM »

As a motion picture photographer, I would be wary of variable ND filters for digital cameras.  For good color, ND filters darker than .9 need to have IR blocking matched to the sensor of the particular camera.  IRND filters made for (at least the older) RED cameras don't work for an Arri Alexa for example and vise versa.  The amount of IR blocking increases as the filter gets darker as well.  The downside is that the darker ND filters also often have an unwanted, but usually correctable color cast to them.  And each filter has a different color cast to boot.  It's a big advantage to have a motion camera with built-in ND filters matched to the sensor and OLPF of a particular camera.

And so, shooting motion with a still camera that has motion capability, is not so easy.  You can't shoot in RAW motion, so a different color correction, in camera, might be needed for each dark ND filter.  When I shoot with an Arri Alexa, I test all the ND filters for color balance and do my best to have a special color correction setting for each filter stored in the camera memory.  And that's when shooting ArriLogC, where it's possible to correct the color cast later in post production.

Variable ND filters don't seem to have this IR blocking at all.  I suspect that you'll find IR contamination of colors when setting the filter above .9ND.

Also, the filter that you linked to has a 3rd polarizer filter built in.  That means that you'll have Polarization all the time.  This is not wanted especially when shooting people.

I wish I could point you to the best solution off the top of my head, but unfortunately I can't.  I understand that there are now filter manufacturers that make heavy ND filters with minimal color shifts and include IR blocking.  3 of these ND filters might cost as much or more than your camera however.

The variable ND might work ok if you stick to no more than ND.9 or maybe 1.2 maximum.  I suggest you test it with both a proper color chart and various faces and fabrics in bright daylight to see if there are problems with IR contamination that can not be easily color corrected later.
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Bruce Alan Greene
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Re: Any recommendations of variable ND filters for motion work?
« Reply #3 on: August 28, 2017, 05:25:53 AM »

A friend who shoots a lot of video has recommended the Lightcraft, Genus, and Schneider brands as all being well made and reasonable neutral.

Does anyone here have other recommendations?

Thanking you in advance,

Ellis
There's only one I use now  (and I have tried a lot) - B+W XS-Pro MRC nano. Yes they are expensive ( I have the 77mm and convert all my lenses to this thread via adapters) but they don't soften the image with longer focal length lenses (a lot do esp the cheaper ones) AND they are multicoated which almost all others are not. Vari ND's have 4 glass surfaces and this makes a very big difference to image quality if you have the sun infront of you. They are also limited to how dark they can go 1-5 stops but you can mod them to go darker by separating the 2 halves and removing the pin that limits the rotation.
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