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Variable ND Filter for Canon 5dmk 11?


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#1 Josh Phoenix

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Posted 30 November 2010 - 12:52 AM

I only have one lens right now which is the canon 17-40mm L. I was wondering what variable nd filter you guys would buy for this lens.
Thank you
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#2 Chris Keth

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Posted 30 November 2010 - 01:14 AM

I don't know of anything called a variable ND.
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#3 Josh Phoenix

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Posted 30 November 2010 - 01:23 AM

Im sorry, the full name is variable neutral density filter. This allows you to make the exposure darker without changing the aperture or shutter speed. This is needed if you want to have a really shallow depth of field (which requires an open aperture) while still maintaing the proper exposure.
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#4 Fred Neilsen

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Posted 30 November 2010 - 01:40 AM

Im sorry, the full name is variable neutral density filter. This allows you to make the exposure darker without changing the aperture or shutter speed. This is needed if you want to have a really shallow depth of field (which requires an open aperture) while still maintaing the proper exposure.


HI,

I'm sure Mr Keth got the ND bit, it's more the variable part - do you just mean a standard ND filter, or is it some sort of contraption where you can actualy change the degree of darkness?

There's no reason a standard screw on Photo ND filter wont work on your lens. The tiffen and lee ones are great, but some of the cheaper ones work fine, your main concern is glass quality and how neutral they really are, you don't want coloured tinting.

Remember one size rarely fits all, you'll probably need to buy two or more filters of different degrees of darkness (you can stack them to get a third even one that's even darker) as well as a soft graduate ND, which come in handy all the time, especialy with the more limited DR of some digital cameras.

Fred

Edited by Frederik Nielssen, 30 November 2010 - 01:45 AM.

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#5 Josh Phoenix

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Posted 30 November 2010 - 02:06 AM

Thank you for that advice. A variable ND is just what the name implies, you can turn the filter and it goes from dark to light. This way you can get the exact exposure without switching out filters. I learned about this watching a Philip Bloom tutorial and it looked pretty cool.
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#6 Fred Neilsen

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Posted 30 November 2010 - 03:55 AM

Thank you for that advice. A variable ND is just what the name implies, you can turn the filter and it goes from dark to light. This way you can get the exact exposure without switching out filters. I learned about this watching a Philip Bloom tutorial and it looked pretty cool.


Ah, I see, I'm sorry for the misunderstanding, they sound very cool though :) You can achieve something similar with two polarizing filters in rotating filter trays, I guess that might be a variable ND is.

Fred

Edited by Frederik Nielssen, 30 November 2010 - 03:57 AM.

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#7 Adrian Sierkowski

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Posted 30 November 2010 - 10:13 AM

As far as I know the only "variable ND" out there is a made by rosco which is a gel/filter combo. Filter on camera, gel on a window. I've seen that. Aside from that, just stick with normal old ND filters much easier and more importantly, repeatable.
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#8 Josh Phoenix

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Posted 30 November 2010 - 01:34 PM

I think I found what im looking for, thanks for all the replies! This filter below changes the exposure when turned and it has markings so you know how many stops it is blocking.
http://www.bhphotovi...al_Density.html

Edited by Josh Phoenix, 30 November 2010 - 01:36 PM.

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#9 Brian Drysdale

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Posted 30 November 2010 - 03:51 PM

I believe this works using the 2 polarising filters mentioned by Frederik.
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#10 steve hyde

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Posted 09 April 2011 - 11:15 AM

I'm using Singh-Ray Variable ND. I find it to be an essential item for shooting cinema on the 5D mark 2 in bright sunlight. It offers about eight stops.
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#11 Stuart Brereton

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Posted 09 April 2011 - 12:12 PM

Interesting. If they are using 2 polas to do this, how are they avoiding the extreme color shifts that tend to happen? I've messed around with a pair of circular polas in the past and found that with anything more than a 2 stop reduction there is a magenta shift that can be hard to balance out. I've certainly never achieved anything like the 8 stops they are claiming.
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#12 steve hyde

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Posted 09 April 2011 - 04:32 PM

Interesting. If they are using 2 polas to do this, how are they avoiding the extreme color shifts that tend to happen? I've messed around with a pair of circular polas in the past and found that with anything more than a 2 stop reduction there is a magenta shift that can be hard to balance out. I've certainly never achieved anything like the 8 stops they are claiming.



I don't know the difference between a neutral density filter and polarizing filter, but I have not noticed any color shifts with the Singh-Ray scalable ND.
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#13 Jon Schweigart

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Posted 09 April 2011 - 07:29 PM

If you have a mattebox Light Craft Workshop just came out with two variable 4x4 ND filters that's equivalent to a 2-8 stop ND set. They also make regular screw on variable ND filters.

http://www.lightcraf....com/product/68
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