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Author Topic: ND Filter for video - how to use?  (Read 6441 times)

schemula

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ND Filter for video - how to use?
« on: February 22, 2012, 10:47:01 PM »
I shot an interview a while back, and I messed up.

I rented an Arri 3 light kit and set everything up and, wow, it was nice and bright, and for some brain fart of a reason, turned the shutter speed up, and it was strobe and stutter looking.

So, I obtained a 1.8 (10-stop) ND filter.

I don't own the light kit, so... I whipped up this quick test by just leaving the white balance to auto, and messing with just the shutter speed. For video I will want 1/60, but for this test I just ended up at 1/80. I have a small "daylight" fluorescent desk lamp and just shot straight into it.

These are just the raw shots:
No ND Filter
*
ND Filter
*

For these I sampled the red circle area with the white eyedropper in Photoshop Levels:
No ND Filter
*
ND Filter
*

Not too bad really.

In the first batch, within reason, the detail came out close and in the corrected set it was not hard to almost get the white matched up. Not perfect, for for the small amount of work I put into it, pretty close.

What are some production tips I might can use to make this ND filter work? I won't know if 1.8 is too dark until I get the light kit again. I doubt the light kit will be as bright as shooting straight into this desk lamp and I still have aperture and ISO settings to futz with to keep the shutter dialed in at 1/60. I could use a custom white balance. What else?

I use a T2i and a 70-200mm f2.8 L Lens. At some point I will want to use these larger apertures to get that DSLR shallow DoF, so I just left the lens at 2.8 for this test.
« Last Edit: March 21, 2013, 11:10:42 AM by schemula »

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ND Filter for video - how to use?
« on: February 22, 2012, 10:47:01 PM »

cinema-dslr

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Re: ND Filter for video - how to use?
« Reply #1 on: February 25, 2012, 02:06:06 PM »
you should leave your shutter on  1/60th
As for the ND filter a variable ND filter is a simple way to control the light so you can keep your diafragma at 2,8.
With fixed ND filters a range of 0,5 to 6 stops is a lot more helpful than a 10stop
Of course lowering the light levels is also a way to go.
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Cornershot

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Re: ND Filter for video - how to use?
« Reply #2 on: February 25, 2012, 03:30:24 PM »
Not sure what you're saying here. Are you having problems with flicker from the cfl's? The ND filter just allows you to keep your aperture wide open typically when shooting in very bright light like a sunny day. The variable NDs allow you to dial in how much light reduction you need. I've never used the Arri lights so don't know what kind of ballast they use. I've never had flicker issues with Kinos. Just drop your shutter speed.

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Re: ND Filter for video - how to use?
« Reply #3 on: February 25, 2012, 03:37:37 PM »
I personally like to shoot a neutral reference for WB with the filter on and set it in the camera before recording (I have a WhiBal and it works great). With AWB, daylight looks ok without a filter but there's a cool color cast with filter on. I have a Hoya Pro1-D ND x16 (4 stops) btw. With a neutral reference, both of them look pretty much the same and the colors look great.

cinema-dslr

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Re: ND Filter for video - how to use?
« Reply #4 on: February 25, 2012, 04:17:50 PM »
The poster had no ND on this particular shoot but wanted to shoot with diafragma 2,8 because of DOF.
He accomplished this by setting his shutterspeed at a high number.
For video this can give problems with light setups because they are transmitting at a freq. of 50/60Hz (depending were you are on this blue globe).
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neuroanatomist

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Re: ND Filter for video - how to use?
« Reply #5 on: February 25, 2012, 04:48:54 PM »
Your white balance is off because the 10-stop ND filter has a warming effect (my B+W 77mm and Schneider 82mm 10-stoppers do). 
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Mt Spokane Photography

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Re: ND Filter for video - how to use?
« Reply #6 on: February 25, 2012, 04:59:21 PM »
I doubt that a lighting kit used indoors will produce anough light to require a ND filter to let you use a lens wide open.  It will certainly not be a 10 stop ND filter.  ND's come in handy in bright outdoor sunlight to allow you to use a wide aperture and thus achieve shallow depth of field.  At ISO 100, you probably will not be able to use f/2.8, even without the ND filter.

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Re: ND Filter for video - how to use?
« Reply #6 on: February 25, 2012, 04:59:21 PM »

Lyra Video Productions

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Re: ND Filter for video - how to use?
« Reply #7 on: February 25, 2012, 07:06:17 PM »
I agree with previous poster--if you can, get a variable neutral density filter.  This will let you keep the same shutter, aperture and iso (more or less) and only change your neutral density--it feels much the way you would adjust the iris ring on a normal video camera.  If it's not too late and you have the funds, i'd say return the one you got and get a variable filter.

If that's not a choice, remember, you don't have to depend solely on the camera/filters to adjust the intensity of light--doing something simple like moving a light forward or back can make a huge light intensity difference--not to mention those kits always come with scrims to cut light output (at least a little).  Good luck.

schemula

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Re: ND Filter for video - how to use?
« Reply #8 on: February 26, 2012, 02:53:37 AM »
Thanks for the replies.

Yeah, to clarify, I now know to keep the shutter at 1/60, but after I set the lights up, it was too bright and I foolishly upped the shutter speed which introduced the strobing effect. The lights themselves had nothing to do with the strobing.

So, in an effort to make 1/60 work I got this ND filter, which, once I saw it, immediately suspected was going to be too dark, and I have read about the color cast.

In this case it was a small room, so moving the lights back was not an option, though I could have should have used scrims.

I may return this filter (it was $184) and pick up a variable or a couple of filters that are less strong.

Living and learning.

Thanks!
« Last Edit: February 26, 2012, 02:57:40 AM by schemula »

NormanBates

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Re: ND Filter for video - how to use?
« Reply #9 on: February 26, 2012, 04:10:47 AM »
check out this:
http://www.similaar.com/foto/tuten/630.html

and this (specially the color cast tests at the end, but also the sharpness issues of the LCW fader ND -and most faders, actually- in case you're considering one of those):
www.similaar.com/foto/lenstests/lenstestsn.html

Cornershot

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Re: ND Filter for video - how to use?
« Reply #10 on: February 26, 2012, 04:20:58 AM »
Actually, all cfl's do flicker or strobe. You can really see it on the cheaper lights and if your power source isn't good or your batteries are low. It also depends on the ballast they use.

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Re: ND Filter for video - how to use?
« Reply #11 on: February 26, 2012, 04:26:41 AM »
check out this:
http://www.similaar.com/foto/tuten/630.html

and this (specially the color cast tests at the end, but also the sharpness issues of the LCW fader ND -and most faders, actually- in case you're considering one of those):
www.similaar.com/foto/lenstests/lenstestsn.html

If renting lights, try to get some that have less light or adjustable output, you do not want to use ND filters except as a last resort.

Filming surfing in Hawaii, you have no control over lighting and must use ND's, but in a studio, you should be able to control the lighting, and dimmer lights are better on everyone.

I still have some 1500 watt tota lights I used in the early days of video camcorders.  They fry everything in a small room.

Positron

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Re: ND Filter for video - how to use?
« Reply #12 on: February 26, 2012, 04:33:16 AM »
Your white balance is off because the 10-stop ND filter has a warming effect (my B+W 77mm and Schneider 82mm 10-stoppers do).

That doesn't sound very "neutral" at all! Do all 10-stoppers have that problem? And if so, why?

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Re: ND Filter for video - how to use?
« Reply #12 on: February 26, 2012, 04:33:16 AM »

Kernuak

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Re: ND Filter for video - how to use?
« Reply #13 on: February 26, 2012, 06:21:31 AM »
Your white balance is off because the 10-stop ND filter has a warming effect (my B+W 77mm and Schneider 82mm 10-stoppers do).

That doesn't sound very "neutral" at all! Do all 10-stoppers have that problem? And if so, why?
I haven't used them, but I think it is one of the pitfalls of the high stop ND filters. I've certainly come across similar reports with the Lee Big Stopper.
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NormanBates

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Re: ND Filter for video - how to use?
« Reply #14 on: February 26, 2012, 06:46:59 AM »
when you're filtering a lot of light out, all ND filters have some color cast
my cheap tiffen have nearly no cast indoors, but they have some IR issues
http://www.similaar.com/foto/lenstests/lenstestsn.html
(the resolution tests, indoors, show no cast; the outdoor tests go green-ish as I increase filtration and stack glass; as shown there too, it's easily corrected by using custom white balance)

the higher-end tiffen NDs solve part of that issue, but again not all
http://www.hurlbutvisuals.com/blog/2010/02/10/filtration-beware-of-the-reaper-of-cheap-glass/

and they're not extremely expensive, but not cheap either
http://www.amazon.com/gp/product/B004W2NDIS/ref=as_li_ss_tl?ie=UTF8&tag=similaar-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B004W2NDIS

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Re: ND Filter for video - how to use?
« Reply #14 on: February 26, 2012, 06:46:59 AM »