Filter for dispersion in the sky

Romanko · Jan 4, 2024

When I look through the side window of my car while wearing sunglasses I see something like this:

Note the dispersion in the sky while the clouds and the grass retain their color. The effect is best observed when the sun is at the right angle to the scene.
The image is made using a DSLR with the sunglasses placed in front of the lens.

Are there any filters that could recreate this effect?

runswithsizzers · Jan 4, 2024

I assume your sunglasses are the polarizing kind? I sometimes see this effect when wearing polarized sunglasses and looking through safety glass. I believe it is the plastic layer of safety glass which causes the effect on polarized light. So try a polarizing filter, but I don't believe you will see this effect except when shooting through the car window.

Romanko · Jan 4, 2024

The sunglasses are polarizing. I think you are right. The safety glass usually has three layers with the plastic layer in the middle. I can probably make a filter out of a piece of safety glass to use in front of a polarizer filter.

runswithsizzers · Jan 4, 2024

Romanko said:
The sunglasses are polarizing. I think you are right. The safety glass usually has three layers with the plastic layer in the middle. I can probably make a filter out of a piece of safety glass to use in front of a polarizer filter.

I was thinking the same thing, but I expect the safety glass will be difficult to work with. Rather than trying to shape the safety glass round to fit in a threaded filter ring, it might be easier to get a filter holder made for square filters? A basic tile cutting saw with a wet diamond blade might work to cut the glass in straight lines. Of course, if you can determine what kind of plastic is used in the safety glass laminate, the plastic might be all you really need?

Sirius Glass · Jan 4, 2024

Polarizing sunglasses or a polarizing filter could cause those artifacts. If one were to use a very wide angle lens such as a 20mm lens and put a polarizer on it, the effect of the polarization will vary from one side of the frame to the other. That is why I stopped using polarizing filters on very wide angle lenses.

xkaes · Jan 4, 2024

There are lots of "colored polariser" filters out there. Some have a polarizer built-in, while others are designed to be used with a polarizer. Some have one color -- green, red, orange, etc. -- while others have two -- red/green, blue/orange, etc.

As you turn the polariser, the color intensifies or the color changes.

An inexpensive way of trying this is to use a polarizer with a color filter. The color will appear or disappear more or less in the areas in the scene that are polarized. In scenes with a lot of polarized light there will be a dramatic change.

Rayt · Jan 4, 2024

I have a pair of Maui Jim sunglasses for driving and everything I see through the windshield is gorgeous much better than when I shot Velvia with a polarizer.

koraks · Jan 4, 2024

Rayt said:
I have a pair of Maui Jim sunglasses for driving and everything I see through the windshield is gorgeous much better than when I shot Velvia with a polarizer.

Same here with a pair of Polaroid sunglasses. Cloudy skies compress extremely nicely into beautifully differentiated 'cauliflower' shapes. The polarizer filters I have for my lenses don't even get close to it.

runswithsizzers · Jan 4, 2024

It seems to me that the polarizing effect I see from my older linear polarizing filters is much stronger than what I see from more recent circular polarizers.

Romanko · Jan 4, 2024

runswithsizzers said:
it might be easier to get a filter holder made for square filters

Yes, this was the intent.

runswithsizzers said:
A basic tile cutting saw with a wet diamond blade might work to cut the glass in straight lines.

Do you mean the mechanical tile cutter or the wet-saw?

runswithsizzers said:
Of course, if you can determine what kind of plastic is used in the safety glass laminate, the plastic might be all you really need?

I can probably figure it out but I am not sure if sandwiching the plastics between two sheets of glass will work. The interfaces will never be perfect unless the plastics is welded into glass.

xkaes · Jan 4, 2024

runswithsizzers said:
It seems to me that the polarizing effect I see from my older linear polarizing filters is much stronger than what I see from more recent circular polarizers.

I've noticed that too, but I've never investigated it. I'm sure someone has. We can't be the only two that have noticed it.

runswithsizzers · Jan 4, 2024

Romanko said:
Yes, this was the intent.

Do you mean the mechanical tile cutter or the wet-saw?

Diamond rim circular saw running in wet bath. My wife works with mosaic and she uses a cheap (less than $100US) diamond tile saw to cut all kinds of rock, glass and stone. I doubt the score-and-snap tile cutters will work on safety glass, but never tried it.

Romanko said:
I can probably figure it out but I am not sure if sandwiching the plastics between two sheets of glass will work. The interfaces will never be perfect unless the plastics is welded into glass.

I was wondering if the plastic, alone (no glass) might work? Assuming it can be found in a rigid sheet form...

Romanko · Jan 4, 2024

runswithsizzers said:
Diamond rim circular saw running in wet bath.

Thanks. I have one. Never tried cutting glass or stone but it can handle thick porcelain tiles if you go slowly.

runswithsizzers said:
I was wondering if the plastic, alone (no glass) might work?

The plastics is very flexible and will need some support.

I don't think I am ready to venture into custom filter design at the moment. I hoped I could just find a combination of available filters to reproduce the effect.

Filter for dispersion in the sky

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