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gels and their use ?


mark_pohl

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You can get gel�s for a variety of effects and purposes. Including your desire, ND, that comes in ND3 (-1/3 of a stop), ND6 (-2/3rds f a stop), and ND9 (-1 stop). Another common use for gels is colour correction, for tungsten and daylight light sources to balance for tungsten and daylight film. They are CTO, orange gels to correct from daylight (daylight light balanced source) for tungsten film. The counter part is CTB, a blue gel used on tungsten light to correct to daylight temp. You can use either of the CTO or CTB to go beyond or below correcting temperatures, and use them to warm or cool your lighting effects. The CTO and CTB come in 1/8, 1/4, 1/2, and �full�. These are the most common three forms of gels, there are however �minus green� for fluorescents or just for fun, as well as yellow, green, red, etc for stage lighting and theatre.
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Fot attaching gells to lights, I use cloths pins, it works. There is accutally a technical motion picture name for them (ec-10 clamp, something like that), but they're just cloths pins really. For attaching gells to on camera type flashes, small pieces of gaffers tape work well too.

 

Peter

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"Including your desire, ND, that comes in ND3 (-1/3 of a stop), ND6 (-2/3rds f a stop), and ND9 (-1 stop)."

 

Sorry Eric, you're way off base here. An ND3 is -1-stop, ND6 -2-stop, ND9 -3-stops, {and ND12 -4-stops}. These are DIN numbers which means that a ND3 is actually 10^(-0.3) = 1/2; ND6 10^(-0.6) = 1/4; ND9 10*(-0.9) = 1/8; and lastly ND12 10^(-1.2) = 1/16.

 

10^X means base 10 raised to the power of X.

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geez, i missed half of my post now...

 

Mark, you can get them many places. They often end up in the garbage too, after shows, or if they've been used a few times. Pro's don't like the wrinkles and creases they sometimes get, so in the bin they go. And in the bin Eric goes after them! But to get familiar with what's out there, type 'Lee gel filters' or rosco into google for starters.

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Rosco filters are sold in sheets which are about 20"x20" (guess). If they are mylar, fine,

mylar does scratch as readiily as acetate. And yes, I am talking about filters for lighting.

Early in the century gels were used for lighting, too. After using a colored filter, you may

not need to use any neutral density filters.

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