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How many stops do silks cut?


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#1 Jim Feldspar

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Posted 27 June 2007 - 06:21 AM

I know that silks are used for diffusion but I'm also wondering if there is a uniform
figure for how much light is cut. When a silk gets pulled off of a grip truck for a 12'
by, I've never heard anybody say which one do you want? In the 18" x 24" flag kits,
there are single and double nets but only one silk. Is that silk the same in terms of
diffusion/cutting light as a silk for an overhead? My local grip huse didn't know offhand
and they're busy (week before the 4th) so I don't want to bug them and ask if I could
come in and measure.

I know that at first it might seem that a question about silks should be in the gripping
section but I figure that this aspect might be more of concern to the people lighting.

I'm making some plans and any information would be helpful. Thanks.
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#2 janusz sikora

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Posted 27 June 2007 - 09:38 AM

I know that silks are used for diffusion but I'm also wondering if there is a uniform
figure for how much light is cut. When a silk gets pulled off of a grip truck for a 12'
by, I've never heard anybody say which one do you want? In the 18" x 24" flag kits,
there are single and double nets but only one silk. Is that silk the same in terms of
diffusion/cutting light as a silk for an overhead? My local grip huse didn't know offhand
and they're busy (week before the 4th) so I don't want to bug them and ask if I could
come in and measure.

I know that at first it might seem that a question about silks should be in the gripping
section but I figure that this aspect might be more of concern to the people lighting.

I'm making some plans and any information would be helpful. Thanks.

Depending on the kind of silk they can cut up to one f-stop in the interior. 12x12 overhead will cut less just because you will have more ambiance.
With 24x36 you will just bring light closer if it cuts too much. All in all silk cuts quite a lot. It becomes difficult in Low Key lighting when you work in tight spaces... it bounces a lot and contaminates your ambiance. In this case I use black silk which doesn't bounce much.
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#3 Xavier Plaza

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Posted 27 June 2007 - 09:43 AM

Hi Jim on Road Flags (MSE), Artificial Silk diffuses and diminishes transmitted light by about 1.5 stops, in butterfly you can find they use White Artificial Silk 1.6 stops, when you use others home made "silks", you can find other types of materials replace the traditional silk, then you can see there are different density grades of silks, for this kind of "silk" is better test first

hope help you
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#4 Jim Feldspar

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Posted 27 June 2007 - 04:49 PM

Thanks guys,


I've never come across black silks. Are they for diffusion still?

What are Road Flags? I searched but couldn't find anything, just sites for off road racing flags.

I'm looking to find what would be the right choice and then buy some and make some gear. I went to a
fabric shop that sells "silk" (it is silk but I guess there's all kinds) for $9.99/yd. That's a yard long and
60" wide so I could make a 10' x12' for about $80.00. There's also cheaper silk which has some patterns in it
but as long as it's white that's okay.
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#5 Chris Keth

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Posted 27 June 2007 - 08:58 PM

A new, clean bleached china silk is around a stop. Artificial silk cuts a bit more. Both cut more if they are dirty.
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#6 Xavier Plaza

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Posted 27 June 2007 - 09:40 PM

This is what i'm talking about (road flags)

http://www.msegrip.c...l...cat=4&ID=87
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#7 Jim Feldspar

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Posted 28 June 2007 - 09:23 AM

This is what i'm talking about (road flags)

http://www.msegrip.c...l...cat=4&ID=87


Cool, thanks. A bit out of my price range presently but it's good to know about them and also to
learn a new term.
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#8 Jim Feldspar

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Posted 28 June 2007 - 09:24 AM

A new, clean bleached china silk is around a stop. Artificial silk cuts a bit more. Both cut more if they are dirty.



Thanks!
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#9 Xavier Plaza

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Posted 28 June 2007 - 09:43 AM

Hi Jim take a look in this website you can find this material Griffolyn look this curtains i don't know the price but i use very similar material like silk and for me that help...

http://www.reefindus...oducts.php?id=7


Also look this website if you want to make your own equipment

http://www.theasc.co...tors/page2.html


I hope this help you :P


xavier
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#10 Jim Feldspar

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Posted 28 June 2007 - 04:54 PM

Hi Jim take a look in this website you can find this material Griffolyn look this curtains i don't know the price but i use very similar material like silk and for me that help...

http://www.reefindus...oducts.php?id=7
Also look this website if you want to make your own equipment

http://www.theasc.co...tors/page2.html
I hope this help you :P
xavier


Xavier,

Thank you! I've been going to all sorts of places that might sell materials and doing searches
for do it yourself gear. These sites are immensely helpful. Really appreciate it!
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#11 Michael Nash

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Posted 05 July 2007 - 05:13 AM

Diffusion material does not alter light the same way a net does, so the "transmission" figure is not consistent. A single or double net will reduce the light by 1/2 stop or a full stop (respectively) regardless of the distance from the light source or the size of the net. A silk, however, becomes the light source. The amount of light transmitted will vary with the size of the silk that's illuminated, and with the distance from the silk.

A large silk (like a 12'x12') placed two feet above an actor's head on a sunny day will transmit quite a bit of soft light on the face; but a small 18"x24" silk on a high stand might as well be a solid for the amount of sunlight it cuts at that size and distance.
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#12 Armando Castro

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Posted 05 July 2007 - 08:10 AM

Try this chart as a general rule of thumb:

http://www.miamifilm...abricspec1.html
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