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Old August 8th, 2006, 11:31 PM   #1
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UV Filter is for what purpose?

I understand UV filters are meant to absorb less UV light. I'm trying to film some cloth that is illuminated with UV light. Would this filter help me get better footage?
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Old August 8th, 2006, 11:59 PM   #2
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A UV filter is meant to prohibit the passage of UV light rays in outdoor bright sun conditions. The presence of excessive UV leads to a slight hazing of the image, effectively reducing contrast and color saturation in the process. The UV filter on the front of the lens is for combating those issues.

Indoors, it is a 'clear lens cap' as some have called it. Filters never add anything. They always take away something which is why they are called filters.

-gb-
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Old August 10th, 2006, 09:49 AM   #3
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Good pt about filters not adding anything. I forgot about the basic principles! Thks.
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Old August 13th, 2006, 09:22 AM   #4
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Quote:
Originally Posted by Sean Seah
I understand UV filters are meant to absorb less UV light. I'm trying to film some cloth that is illuminated with UV light. Would this filter help me get better footage?
I'd advise you to avoid doing this. UV radiation is a life killer. It can change the DNA (cause cancer), can affect the immune system and can seriously damage the eyes (up to blind) etc. Even a plastic exposed to UV for some time will be damaged!

BTW, a UV filter is completely useless in places other than the highest mountains. It has no effect in low heights -except as a lens protection that is worth having only if it is a multilayer type.
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Old August 13th, 2006, 09:46 AM   #5
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Originally Posted by Ken Johnes
I'd advise you to avoid doing this. UV radiation is a life killer.
AFAIK, the output of typical UV lamps (such as flourescent "black lights") should really be way below the threshold of creating problems like this. You are probably getting much more UV exposure when you step outside on a sunny day...
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Old August 13th, 2006, 09:58 AM   #6
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Originally Posted by Boyd Ostroff
AFAIK, the output of typical UV lamps (such as flourescent "black lights") should really be way below the threshold of creating problems like this. You are probably getting much more UV exposure when you step outside on a sunny day...
He didn't say what lamps he will use... I hope I'm wrong guessing the worst case (you can buy harmfull lamps for medical, industrial etc use as well). I've seen posts about geting such lamps and even installing(!) for not creative purposes...
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Old August 13th, 2006, 11:37 AM   #7
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don't use tanning bed lights... :)
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Old August 13th, 2006, 12:45 PM   #8
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There are UV filters intended to be used with UV illumination, vs. those intended to cut UV in a landscape. UV used in illumination is usually used to induce fluorescence in the illuminated scene. The light coming from the fluorescence is in the visual range.
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Old August 14th, 2006, 09:43 AM   #9
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Really Jim =) ?? Actually I'm trying to film chinese Dragon dance. The dragon is painted in UV absording paint and the dancers prance in the dark with some UV lights only. FX1 doesnt work really well in low Lux and we have toi shoot from quite a distance. I heard from someone that there are UV filters that will help but I have no clue if it really works with my usage! For those who may be interested to see what a dragon looks like, please click the link below:

http://www.thephotostation.net/photo...97dragonhd.jpg
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Old August 14th, 2006, 10:05 AM   #10
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From your description Sean a UV filter isn't going to help at all. Glass itself absorbs UV, so the 13 elements in your lens's lineup don't need you to add another one. The filter you add will not be absolutely spotless (impossible in the real world) so you're losing some light, adding some flare and spending money better put into a tripod or mic.

tom.
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Old August 14th, 2006, 11:00 AM   #11
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Oops, I think I didnt explain myself clearly. What I film is a moving dragon, held by 9 men in a dark area illuminated by UV Florescent lamps. The dragon itself is painted with UV absording paint. Hope this is clearer now. Anyway to get better footage in this case?
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Old August 14th, 2006, 08:02 PM   #12
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I'd be more afraid of that dragon eating your camera from your arms. Have you seen one of those things drink a glass of water? Its mind boggling
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Old August 16th, 2006, 09:11 AM   #13
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Ha ha :p I spoke to DSE in person today. He feels adding a wide len may help get an additional F stop. Some gain would definately help too! Will try it out and let u guys know..
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Old August 16th, 2006, 10:42 AM   #14
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I'd cross DSE off your photographic buddy list then. Adding a wide-angle converter always loses you light, never the other way around.
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Old August 17th, 2006, 12:18 AM   #15
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Any converter costs you two f-stops the way I understand the rule. If anyone has any other theories I'd love to hear them. I've always wondered if all lens converters were equal when it came to acting like .06 ND filters.
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