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Infrared Contamination with Heavy ND Use


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#1 Michaels

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Posted 09 February 2011 - 01:09 AM

I have heard that there is a possibility of colour shift and colour contamination to the image if one uses a lot of ND s. i.e. the proportion of IR increases as you reduce the visible spectrum reaching the chip. I'm new to the Red but as it seems comfortable rated at 320ASA then in harsh daylight you would want to use a 1.2 ND to get your exposure down to where any lens will perform best at around 5.6 or much more for wider stops for selective DOF. Is this a problem and how do you correct it?
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#2 Brian Drysdale

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Posted 09 February 2011 - 05:10 AM

You use an ND filter that also filters out the IR. The filter manufacturers have these as part of their ranges.
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#3 Keith Walters

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Posted 09 February 2011 - 08:12 PM

I have heard that there is a possibility of colour shift and colour contamination to the image if one uses a lot of ND s. i.e. the proportion of IR increases as you reduce the visible spectrum reaching the chip. I'm new to the Red but as it seems comfortable rated at 320ASA then in harsh daylight you would want to use a 1.2 ND to get your exposure down to where any lens will perform best at around 5.6 or much more for wider stops for selective DOF. Is this a problem and how do you correct it?

This has been extensively discussed here and elsewhere. The following two threads may help to explain the problem. If you do a search for "IR" or "infrared" you'll no doubt find more.
I doubt you'd have too many problems using a 1.2 ND.

RED and IR


Fun With Filters
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#4 Tim Naylor

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Posted 16 February 2011 - 06:44 PM

My fast rule with IR is anything above ND9, I use IR ND's. Has been working fine. There's a pretty extensive test page at reduser.net. I also keep my ND's and IR's the same brand for consistent color shift.
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