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    Color shift problem with use ND's and wider apertures
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    I have e a DVX100b...been using it for about 5 years now...never any problems...fantastic cam.. Within the last two weeks I ran into a odd "color shift" in the greens- where they are taking on a "brownish yellow cast"...with some magenta in there. I don't have a problem typically with apertures over 5.6 for example with any combination of ND's...either in cam or external. The problem occurs when I have a .6 and a .3 ND in the matte box and start to open up from say 4.8 to OPEN...which are stops I use for certain rack focus moves. I've included a side by side low rez image shows image with and without problem...and was taken with sun behind me about 4:00. Any help, comments, advice would be much appreciated...I'm shooting production right now, and would like to figure this out asap.
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    #2
    Mod v2.0 Noel Evans's Avatar
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    SO white balance isnt in the mix of this at all insofar theyre all using the same WB?
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    #3
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    I was using the 56k preset both times it happened...and tried a manual white balance...same result


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    #4
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    Have you tested the 0.3 ND for color shift? Tried it on another camera? Just to be sure.


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    #5
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    Looks like IR contamination. Depending on the strength of the particular camera's on-sensor IR filter, an additional IR or "hot mirror" filter is needed when using ND above .9-1.5 or you will get magenta hues in the shadows/blacks. This is standard practice with all digital cinema cameras.


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    #6
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    Will look into IR issue...in interim...read other postings elsewhere about similar issues with "ND filter stacking"


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    #7
    Moderator David Jimerson's Avatar
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    Quote Originally Posted by brandtb View Post
    I was using the 56k preset both times it happened...and tried a manual white balance...same result
    How far apart in time were the shots? Daylight changes constantly; a constant white balance may produce differences like this. Then, of course, a manual white balance will give you a totally different result?
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    #8
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    the two images were taken about 20 seconds apart.


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    #9
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    I've just started to look into various "hot mirror" filters...don't have time to exhaustively research these. Can anyone recommend dependable brands/types that are "not going to break the bank"...with the understanding that sometime you obviously pay for what you get.


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