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Difference in diffusion


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#1 siddharth diwan

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Posted 11 February 2007 - 03:46 AM

What is the difference if i use Silk or Muslin or Bleached Muslin or any other diffusion.

Thanks
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#2 David Mullen ASC

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Posted 11 February 2007 - 11:22 AM

What is the difference if i use Silk or Muslin or Bleached Muslin or any other diffusion.

Thanks


There is the efficiency of how it spreads the light -- how evenly in all directions -- and there is the density of the material, which affects how much light is lost but also how far the light fills the material. And there is the color it may add to the light (Muslin is warmer than Bleached Muslin) and there is the issue whether it allows any specular light to leak through the material, creating a faint hard shadow.

And if you're outside in the wind, there is the issue of how much noise it makes flapping around.

They all soften light in different degrees with different textures. Beyond the textural issues, most people need light, medium, and heavy diffusion for various reasons (heavier materials may cut down the exposure too much, lighter materials may not diffuse enough, etc.)

For example, you may put a 4'x4' frame of Bleached Muslin in front of a 5K and find that you've lost too much light and therefore either need to switch to a 10K, or switch to a lighter diffusion like 216. But maybe when you do a closer shot next, you can switch back from 216 to Bleached Muslin and just work the frame or light closer to the subject to get enough exposure.
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#3 siddharth diwan

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Posted 12 February 2007 - 03:40 AM

There is the efficiency of how it spreads the light -- how evenly in all directions -- and there is the density of the material, which affects how much light is lost but also how far the light fills the material. And there is the color it may add to the light (Muslin is warmer than Bleached Muslin) and there is the issue whether it allows any specular light to leak through the material, creating a faint hard shadow.

And if you're outside in the wind, there is the issue of how much noise it makes flapping around.

They all soften light in different degrees with different textures. Beyond the textural issues, most people need light, medium, and heavy diffusion for various reasons (heavier materials may cut down the exposure too much, lighter materials may not diffuse enough, etc.)

For example, you may put a 4'x4' frame of Bleached Muslin in front of a 5K and find that you've lost too much light and therefore either need to switch to a 10K, or switch to a lighter diffusion like 216. But maybe when you do a closer shot next, you can switch back from 216 to Bleached Muslin and just work the frame or light closer to the subject to get enough exposure.



Thanks David for replying......can you also tell me which diffusion cuts more ligth n which one is less....what do u prefer msotly
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#4 David Mullen ASC

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Posted 12 February 2007 - 10:59 AM

I can't go through all of them, but generally you find it's something like (from lightest to heaviest):

Opal, 250, 216, Light Grid Cloth, Full Grid Cloth, Muslin

Although 216 and Light Grid Cloth are very close to each other.

I only use Silks outside and those come in strengths too (lighter China Silk, normal Poly Silk, half strengths of those, etc.) I also use a Half Soft Frost outside, which is more like Opal in lightness (you only lose a 1/2-stop standing under that, versus more then a stop under a Silk.)

There are dozens of others I haven't even mentioned -- these are just the ones I tend to use.

Bleached Muslin is just whiter than unbleached muslin, which has some warmth to it.
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#5 Ricardo Diaz

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Posted 13 February 2007 - 06:39 PM

For exteriors I like to use shower curtain or highlight as I hear it called. It softens sunlight well while still maintaining some intensity like the sun should. Also it has wonderful fall off. It's also not paper therefore it is relatively noiseless. Personal preference of course. Doesnt cut alot of light either.
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#6 David Mullen ASC

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Posted 13 February 2007 - 09:48 PM

For exteriors I like to use shower curtain or highlight as I hear it called. It softens sunlight well while still maintaining some intensity like the sun should. Also it has wonderful fall off. It's also not paper therefore it is relatively noiseless. Personal preference of course. Doesnt cut alot of light either.


Half Soft Frost is similar to a shower curtain material.
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#7 Ken Minehan

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Posted 13 February 2007 - 10:04 PM

Hello David, i was going through the lee filter after you mentioned the half soft frost. Is it something like the lee Half Hampshire frost? By the looks of it it wouldn't diffuse much light at all. Or is it some other gels that i'm not aware of.
Also do you use the shower screen so the difference between the diffused part of frame is not too different from the undiffused, so as to not burn back ground?

Ken Minehan
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#8 David Mullen ASC

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Posted 13 February 2007 - 10:08 PM

Hello David, i was going through the lee filter after you mentioned the half soft frost. Is it something like the lee Half Hampshire frost? By the looks of it it wouldn't diffuse much light at all. Or is it some other gels that i'm not aware of.
Also do you use the shower screen so the difference between the diffused part of frame is not too different from the undiffused, so as to not burn back ground?

Ken Minehan


Half Soft Frost is closer to Opal, heavier than Hampshire Frost. You only lose about a 1/2-stop under Half Soft Frost. Any lighter and there isn't much point to going through the bother.

I sometimes use Half Hampshire Frost on windows where I want to throw the view outside out-of-focus, especially on sets with not-so-great backings outside the windows.
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#9 Ken Minehan

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Posted 14 February 2007 - 02:11 AM

Thats a great tip.
Thanks.
Ken Minehan
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#10 Jeff Webster

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Posted 28 April 2007 - 11:15 PM

If I were to buy rolls of 216 diffusion from say Studio Depot, how would I go about mounting that onto a 4x4 frame since the rolls only come in 2ft widths? Would I just have to buy diffusion specifically made for 4x4 frames or just use two pieces to fill the frame?

I've been on shoots but all the DPs have used silks or bounce, so I'm unsure of how to mount it. I've been reading a lot on here and have seen a lot about 216 and 250 so I really want to begin using this form of diffusion.

Thanks in advance.

Jeff Webster

Edited by Jeff Webster, 28 April 2007 - 11:17 PM.

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#11 David Mullen ASC

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Posted 28 April 2007 - 11:22 PM

Normally you would use the 48"-wide rolls when cutting gel for a 4'x4' frame.
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#12 Jeff Webster

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Posted 28 April 2007 - 11:37 PM

Thanks David. I just went back to the site and feel dumb for not noticing the measurements. I must have been confused. Do you mostly use the 4x4 frame w/ diffusion for more of a wide shot or master than for close-ups (I know you like Kinos for closeups)? I'm just wondering if maybe you just move the frame it a little closer to get more wraparound with a bigger source being closer in the close-ups. Would you recommend using the 4x4 of 216 with a 2k and then a 4 bank kino for closeups?
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#13 David Mullen ASC

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Posted 28 April 2007 - 11:49 PM

A 4' 4-bank Kino is only 4' wide, so it's not softer than a 4'x4' frame of diffusion necessarily (depends on a lot of factors). There is no right or wrong level of diffusion.

But generally, you'd use a larger frame of diffusion on extreme wide shots (if you have the room) like a 6'x6', 8'x8', 12'x12', whatever (just depends on a lot of factors, like how far away this diffusion frame will be and how soft you want the light to look.) In a smaller space, you'd probably use a 4'x4' frame. On close-up, you might walk it in closer and/or switch to a heavier material.

This is really an issue of needing to play around with it to see what works for you.
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#14 Jeff Webster

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Posted 29 April 2007 - 12:45 AM

So if you were to use, say an 8x8 frame, how would you mount that or would use just use premade silks instead of 216 or 250?

Edited by Jeff Webster, 29 April 2007 - 12:45 AM.

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#15 David Mullen ASC

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Posted 29 April 2007 - 12:59 AM

Generally for 8'x8' and higher, you use fabrics like Grid Cloth, silk, or welded plastic material like Soft Frost, etc. already in those sizes, though in an emergency, I have covered an 8'x8' frame with two rows of 216 and some clear tape..
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#16 Rupe Whiteman

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Posted 30 April 2007 - 11:18 AM

... FYI Blain Brown's 'Motion Picture and Video Lighting' shows a good range examples of different types of diffusion - all from the same light source (studio 2k) so it's very useful for reference... Focal Press are publishers.
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#17 Chris Keth

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Posted 30 April 2007 - 12:19 PM

... FYO Blain Brown's 'Motion Picture and Video Lighting' shows a good range examples of different types of diffusion - all from the same light source (studio 2k) so it's very useful for reference... Focal Press are publishers.


It's worth mentioning the unique qualities that woven diffusions (muslins and silks) have. The weave diffuses the light but also lets some portion of it through essentially unchanged so it looks (and is) a bit like a hard source mixed with a soft source coming from the exact same place.
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#18 Sol Train Saihati

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Posted 25 August 2007 - 08:01 AM

Got a shoot coming up and I'm trying to work out my photometrics- although one variable is missing from my equations: how many stops does bleached muslin take off?!

Simple answer - depends on how thick it is. Does anyone have experience with the AFM Lighting bleached muslin? Its pretty thick...

We're shooting on ISO 160 stock and I'm looking to get a 4/5.6 split with the source around 30ft away from the subject through a frame about 20 ft away.

Im hoping that 4 x 10kW fresnels through a 20 x 20 will do it? What do you reckon? We're on a tight budget so I'm trying to get my estimate as close as possible to save us on lamps/dimmers/cables/stands we dont absolutely need.
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#19 Simon Peck

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Posted 23 March 2008 - 04:27 AM

Got a shoot coming up and I'm trying to work out my photometrics- although one variable is missing from my equations: how many stops does bleached muslin take off?!

Simple answer - depends on how thick it is. Does anyone have experience with the AFM Lighting bleached muslin? Its pretty thick...

We're shooting on ISO 160 stock and I'm looking to get a 4/5.6 split with the source around 30ft away from the subject through a frame about 20 ft away.

Im hoping that 4 x 10kW fresnels through a 20 x 20 will do it? What do you reckon? We're on a tight budget so I'm trying to get my estimate as close as possible to save us on lamps/dimmers/cables/stands we dont absolutely need.



You might be better off using unbleached muslin and a 12K HMI, esp. if you're on a budget. Throw a little gel on that thing and you'll still have more light output than 4 10Ks spread through a sheet of diff.
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