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Daylight interior question


Palle Lindqvist
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Yes I can see that ... people have their own ways..nothing wrong with that.. but to set up,construct a book light .. is actually making a lot more work for the same quality of light.. I guess its knocking down the intensity.. but there are easier ways of doing that..

 

Do you deny that a book like can take up less real estate than the setup shown in this thread: http://www.cinematography.com/index.php?showtopic=68944

 

If you just wanted to knock down the intensity vs. soften the light, you'd use a scrim, wouldn't you?

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JD you need to read my post again.. I said when space is not an issue.. and yes agree with your second statement .. that was my point really.. apart from saving space... a book light is only taking down the intensity of the light,by bouncing it internally .. into another scrim/diffusion frame.. instead of directly..

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JD you need to read my post again.. I said when space is not an issue.. and yes agree with your second statement .. that was my point really.. apart from saving space... a book light is only taking down the intensity of the light,by bouncing it internally .. into another scrim/diffusion frame.. instead of directly..

 

If you're referring to post #22, yes I did read it. Don't mix reduction of intensity with the goal of a creating a more diffused larger source. Loss of intensity is a side effect of the scatter in the process.

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Scrims and diffusion are different things

 

.. into another scrim/diffusion frame.. instead of directly..

 

Scrims, wire or fabric aren't the same/don't serve the same purpose as diffusion. If you're just here to argue or nitpick words or semantics, I'm not interested.

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JD... mm not sure what your problem is .. Im not here to argue .. we seem to be talking in circles saying the same thing .. thats what Im saying .. a book light is NOT making the light softer .. agree totally ..reduction of intensity is NOT making the light softer .. but a box light,by having that added bounce internally is cutting the intensity.. but NOT making the light softer.. that can only be done by increasing the size of the source to the subject .. I think we are saying the same thing ?

 

Im just wondering why they are such the rage.. as apart from tight spaces.. they dont make the light softer just by being bounced into a frame.. compared to filling the frame directly by a lamp.. the frame size is still the same..

 

Peace and love.. have a cup of tea or something :)

Edited by Robin R Probyn
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A booklight will make a source softer than the same light just through the same diffusion. You're either using a soft bounce like white, which will scatter more before the diff, or a harder bounce, which adds distance between the fixture and diff and thus creates a larger source on the diff, causing the light to be softer. So a booklight would be good for where you don't have space to get the light far enough from the diff to create a large enough source to wrap/be as soft as you want. But the side effect is that light gets everywhere and if you don't have the grip equipment to deal with that it can be a bit of a pain.

 

So Robyn, you're kind of right in that its really the size of the diff frame that matters in terms of softness, but also a booklight can make light softer by using a soft bounce to double diff the light. As actually in the example I posted earlier for this thread, I put a Joker 800 through opal, decided it wasnt soft enough, and added a sheet of 216 or 250 to the fixture in addition to the opal. Similar effect to using a booklight. The opal is still the "source" but the light coming into it is already soft. Unless you're making your booklights with a mirror, you're definitely adding softness before the diff frame.

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I think I understand what you're saying. Basically the booklight, while cutting intensity, enables you to fill the frame more and evenly, so that though you have to move it closer, it becomes softer because of size.

But what about a hypothetical situation, lets say distance of the setup stays the same. You have a 1k Redhead barndoored which fills your 4x4 of 216, or a 2k Blonde with 250 clipped on it, cut and scrimmed to fill the same frame at the same intensity. The 4x4 is still the source at the same distance and size. The amount of wrap would stay the same because of the size of the source, but wouldn't it still be softer at the same intensity because there's more diffusion in front of the light?

That's what leads me to say the booklight is adding another dimension of diffusion by going first into a bounce before the frame, because obviously you can't always move the light closer to the subject to compensate for the lost intensity, and rather use a larger light into the same setup to get the same intensity with a softer light.

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If the 4x4 diffusion frame is evenly lit from corner to corner with no hot center, then it doesn't matter what fills it, it can't get any softer.

 

So IF the 1K blonde filled the frame evenly and your meter said it was more or less the same intensity across the whole 4x4 surface, it can't get any softer.

 

In reality, 216 is not the heaviest material so probably a 1K blonde would create a soft light that was hotter in the center and thus a little less soft than the theoretical maximum -- and probably the 2K with 250 on it would fill the frame with less of a hot center and thus be softer.

 

Now if you used Full Grid in a 4x4 frame and backed up the 1K so that there was no chance of a hot center on the frame, then it's pretty much as soft as a 4x4 can get, and switching to a 2K with 250 on the doors wouldn't make much of a difference.

 

The advantage of using a bounce light to fill a diffusion frame (i.e. a book light), or a Chimera lamp, or Kinos, etc. is that the broader source fills the frame more evenly with less of a chance of a center hot spot and thus you can get closer to the theoretical maximum softness that the size of the diffusion provides.

 

Instead of a 1K hitting a 4x4 216 frame, you might get a more even, and thus softer, effect with four 250w lamps hitting each quadrant of the frame.

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Will .. as above ..

 

"booklight can make light softer by using a soft bounce to double diff the light"

 

This is tripping you up sir

 

"Basically the booklight, while cutting intensity, enables you to fill the frame more and evenly, so that though you have to move it closer, it becomes softer because of size."

 

Any frame or light source will become softer by moving it closer to the subject.. book light in a tight space is just helping to "fill" the diff frame and avoid hot spots if you cant get your lamp back far enough.. but you can also bounce a light in that situation to same effect..

 

 

Im guessing they have a studio at your school.. its very easy to set up a frame/light and move it back/forth from the subject .. or use small and bigger frames.. a 10 K through a big frame far away from your subject will be a hard light..

​A classic example is the sun.. thats a very very big source .. but its a long way away .. so its anything but soft on a clear day.. but a cloudy day is providing a massive diffusion frame .. very close to us.. so the light can be very soft ..

 

JD.. putting a light through fabric can very much be used to diffuse light .. many of the greats have been doing this for years .. dying the fabric to their own custom likes..

Edited by Robin R Probyn
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JD.. putting a light through fabric can very much be used to diffuse light .. many of the greats have been doing this for years .. dying the fabric to their own custom likes..

 

Did I ever say that it didn't?

 

What I tried to say and you don't seem to understand is that a scrim, can made of wire or fabric, fabric scrims, more often call nets, aren't the same as diffusion material. You don't seem to comprehend the difference.

 

I'm done with all your BS.

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  • 2 months later...

A booklight will make a source softer than the same light just through the same diffusion. You're either using a soft bounce like white, which will scatter more before the diff, or a harder bounce, which adds distance between the fixture and diff and thus creates a larger source on the diff, causing the light to be softer. So a booklight would be good for where you don't have space to get the light far enough from the diff to create a large enough source to wrap/be as soft as you want. But the side effect is that light gets everywhere and if you don't have the grip equipment to deal with that it can be a bit of a pain.

 

So Robyn, you're kind of right in that its really the size of the diff frame that matters in terms of softness, but also a booklight can make light softer by using a soft bounce to double diff the light. As actually in the example I posted earlier for this thread, I put a Joker 800 through opal, decided it wasnt soft enough, and added a sheet of 216 or 250 to the fixture in addition to the opal. Similar effect to using a booklight. The opal is still the "source" but the light coming into it is already soft. Unless you're making your booklights with a mirror, you're definitely adding softness before the diff frame.

 

Will,

 

Your first experiment-book lighting shows that it is useful when not possible to increase the distance between light-source and diffusion frame.

 

But in the second experiment you are using 2 layer diffusion in front of the light-source.

 

Can we compare these 2 experiments? Would it provide the same results?

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The softness is determined by the size of the source relative to distance -- a book light only makes it softer if it helps fill the diffusion frame more evenly from corner to corner but once you do that, the size is what is determining softness.

 

David,

 

> The softness is determined by the size of the source relative to distance

 

Could you explain 'size of the source relative to distance'?

 

>a book light only makes it softer if it helps fill the diffusion frame more evenly from corner to corner but once you do that,

 

Would it be possible fill the diffusion frame more evenly from corner to corner, so that a light meter provide the same reading throughout the frame?

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Im sure David can answer this better.. but its easy just to try it and see.. if you hold your finger of one hand a couple of inches away from the palm of your other hand.. and move both hands together at the same time keeping the same distance between finger and palm.. towards and away from any light source .. you will see the shadow of your finger,on the palm of your other hand, get soft as you move towards the light,and hard as you move away.. its the laws of physic,s..

 

So for a very basic set up.. a head and shoulders interview.. if you want a soft key light.. you want to get the biggest size light source .. usually this is easiest done using a diffusion frame in front of the light.. then the diff frame becomes the light source .. not what ever is behind it.. and get it as close as possible to your interviewee.. personally I wouldn't bother using a light meter to judge if you have filled the frame evenly.. .. this is where a book light is good.. if can help you fill the diff frame evenly when you don't have the space to back your source light to evenly fill that diff frame.. but doesn't intrinsically make the light softer.. as the actual source is the same size regardless which way you fill that diff frame.. well thats as I know it anyway.. !

Edited by Robin R Probyn
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The softness is determined by the relative size of the source (and when using diffusion frame or bounce, that becomes the source, not the lighting unit hitting that material).

 

I say "relative" because I'm not so much talking about the physical measurement of the source but how big it appears relative to the POV of the person being lit by that source.

 

In other words, to the person being lit, if a 4'x4' diffusion frame in front of them takes up the same area of their vision as a 20'x20' diffusion frame much further away, then the two sources would be equally soft in terms of the shadow patterns created.

 

The difference would be the fall-off speed, the bigger, farther light falling-off in exposure more gradually compared to the smaller, closer light. If a diffusion frame is only a few feet from a face, then the actor leaning towards or away from it would cause a visible change in brightness on their face -- but if the frame was several feet away, then leaning towards or away from it shouldn't cause much of an exposure change.

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The softness is determined by the relative size of the source (and when using diffusion frame or bounce, that becomes the source, not the lighting unit hitting that material).

 

I say "relative" because I'm not so much talking about the physical measurement of the source but how big it appears relative to the POV of the person being lit by that source.

 

In other words, to the person being lit, if a 4'x4' diffusion frame in front of them takes up the same area of their vision as a 20'x20' diffusion frame much further away, then the two sources would be equally soft in terms of the shadow patterns created.

 

The difference would be the fall-off speed, the bigger, farther light falling-off in exposure more gradually compared to the smaller, closer light. If a diffusion frame is only a few feet from a face, then the actor leaning towards or away from it would cause a visible change in brightness on their face -- but if the frame was several feet away, then leaning towards or away from it shouldn't cause much of an exposure change.

 

Does anything happens to the characteristics of light rays when it is passing thru diffusion frame?

Edited by Mathew Collins
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The light rays get scattered and diffused...

 

Different diffusion materials have different effects, besides the amount of softening. Some cloth fabrics with a porous weave allow faint hard light to leak through so you get this interesting soft-hard effect. Fabrics that spread the light in a 4-point star pattern like silks create a different softness than a plastic diffusion that spreads a lot evenly in all directions across the material.

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Book lighting through a 4x4 isn't going to necessarily be any softer than going directly through a 4x4 diffusion -- the softness is determined by the size of the source, book-lighting just makes sure you are softening enough to fill that source (the diffusion frame) more evenly. But if you go directly through a heavy diffusion material like a 4x4 full grid or 129 diffusion, a book-light version isn't going to be any softer if all it ends up going through is a 4x4 frame.

 

I guess I'm just a bit tired of people promoting book-lights as some sort of magic method of achieving extra softness. The only way to increase softness is to increase the size of the source, so if a book-light allows you to fill, let's say, an 8x8 frame of diffusion in a small space, then it makes sense. But a 4x4 frame is not hard to fill in a small space so there isn't a lot of reasons to book-light it unless you can only get ahold of some weak diffusion material like 250 or Opal and thus need to soften the light before it hits the frame.

I've been guilty of this. The first time someone walked me through building a book light, they explained it like Voodoo. Common sense eventually helped me understand how it actually works but it's always reaffirming to hear.

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