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Emulating light through a dirty window


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How would you emulate the light coming through an old dirty window? Do you have a standard solution? (I'm not talking about the window frame but the texture)

Preferably something that would not burn in front of a tungsten light, but a "led version" would be interesting too.

 

dirty2.jpgdirty1.jpg

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You can experiment with a simple wooden frame (or two stacked an inch or so apart like the picture). Maybe you can shear different levels of light diff by running a blade through them vertically, to mimick varying intensities of light. You can probably dirty the diff as well. But,  why not just make the real thing? Pick up an actual cheap window with a frame pattern you like and also has the glass and dirty it up? There’s spray that is meant to stick to windows to make it seem frosted. Maybe that mixed with little particles (sand, etc).  I’m sure it will take some experimenting. A good art dep person might have some great ideas, too.

Edited by Joseph Tese
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1 hour ago, Joseph Tese said:

You can experiment with a simple wooden frame (or two stacked an inch or so apart like the picture). Maybe you can shear different levels of light diff by running a blade through them vertically, to mimick varying intensities of light. You can probably dirty the diff as well. But,  why not just make the real thing? Pick up an actual cheap window with a frame pattern you like and also has the glass and dirty it up? There’s spray that is meant to stick to windows to make it seem frosted. Maybe that mixed with little particles (sand, etc).  I’m sure it will take some experimenting. A good art dep person might have some great ideas, too.

Thanks for the suggestions... I was looking for something more portable and easy to store solution. If I  used plexiglass instead of real glass it could work. My initial thoughts was to experiment with some semi-transparent plastics and maybe tear some holes and see how it looks like. Some sheer curtains could also work, but they often look too even or they have some repeating pattern.

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48 minutes ago, Phil Rhodes said:

Yes, the frosting spray. Even spray paint for denser grime. The variable diffusion density of dirty glass is easy to create that way.

I was searching for some "emulation" in case I don't have a window at all, and I would not like to use big and heavy real glass windows. Maybe a thin plexiglass with frosting spray could work.

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Use an ellipsoidal light like a Source4 Leko and put a gobo in the slide holder. A Dedolight with a beam projector would work as well. Otherwise, you’ll need a large frame with your ‘dirty window pattern’ close to the subject to get a sharp shadow, as Joseph and Phil suggested.

Using a collimated light source like the Leko let’s you put the pattern much closer to the light, keeping it much smaller. You can also do a combination effect, like using a Leko and putting your own cukoloris a few feet in front of it. It won’t be as sharp of a pattern, but it may be what you’re looking for. 

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To actually get that pattern of dried dirty water that rained down a window, it would be best to basically create a "dirty window gobo" to shine a hard light through -- as mentioned above by Phil, you could use clear gel on a metal or wooden frame, like a 4'x4' frame, and then dust it up and then spritz it with water so that it creates clear vertical lines.

I suppose a more abstract version could be created with a frame of something like 1/2 Hampshire Frost and cutting some wavy vertical lines down through it but it probably would all fall apart once shredded!

I don't know if one could create a glass filter gobo for a Source-4 Leko with this effect painted onto it. I think clear gel would melt inside the gobo slot for a Source-4. Maybe cut a circle of clear heat shield material?

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Thanks Satsuki and David, really good suggestions. I think I'll test some gel (like 1/4 CTB) and make it dirty (I don't have clear gel!) and see how it looks.

How would a glass gobo with really scratched surface look when projected from a Leko?

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40 minutes ago, Jan Sandvik said:

How would a glass gobo with really scratched surface look when projected from a Leko?

My guess is that it would have quite a bit of chromatic aberration around the scratches. Probably not what you want. Maybe you can try the same ‘dried water’ treatment you were going to do on the clear gel frame instead? The nice thing is that you should be able to throw it in and out of focus with the lens. 

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