# [Wet Thumb Forum]-Polarizing glass/film



## JamesHoftiezer (Feb 2, 2003)

We were on another topic that got me thinking. Most of us are familiar with the washout from the lights in many of our tanks. When viewing or taking pictures the diffusion of the lights can sometimes distract from the color of the plants.

When I get my new camera, the main decider for me is the ability to use polarizing filters on it, to eliminate (I hope) the wash out in my pictures, but I was thinking....

Is there a way to use polarized glass or film on aquariums so as to eliminate the washout?
Can you use window/car tinting film on your top glass under the lights?
Can you replace the the top glass with a polarized glass?
Would it reduce the overall light getting to the plants? ... 10%...50%?

Would you put it on the front of the aquarium for viewing?

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## JamesHoftiezer (Feb 2, 2003)

We were on another topic that got me thinking. Most of us are familiar with the washout from the lights in many of our tanks. When viewing or taking pictures the diffusion of the lights can sometimes distract from the color of the plants.

When I get my new camera, the main decider for me is the ability to use polarizing filters on it, to eliminate (I hope) the wash out in my pictures, but I was thinking....

Is there a way to use polarized glass or film on aquariums so as to eliminate the washout?
Can you use window/car tinting film on your top glass under the lights?
Can you replace the the top glass with a polarized glass?
Would it reduce the overall light getting to the plants? ... 10%...50%?

Would you put it on the front of the aquarium for viewing?

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## MarcinB (Apr 16, 2004)

James, does a polarizing filter significantly improve the quality of a tank photos? Could you show us some examples of the same shots taken with and without this filter?

150L (40G) planted tank
click here for photo


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## Rex Grigg (Jan 22, 2004)

Due to the nature of polarization I would have to guess using it under the lights would cut down on the light entering the tank. I wear polarized glasses instead of sun glasses and the amount of light is cut way back. I wear them due to the glare of the sun on the mail. I'm not sure how much it would cut down on the light but cut down it would. And since most of us have worked hard to get light into the tank why would we want to cut down on the light?

If you put it on the front of the tank the tank would appear a lot darker, and also you might get a nice moire look.

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## George Willms (Jul 28, 2004)

Polarizing could cut down on the light coming through. The effect of a polarizing filter is to only let light waves oriented in a certain direction through and block all others. It is a fairly classic demonstration where you take two plastic polarized sheets on top of one another and rotate one of them. As you turn them you will gradually see less light and eventually almost no light and then back to less light as you go through a 360 degree rotation. There will be a point where almost all the light gets through and a point where almost no light gets through.

If you are interested in window films, I know they make a clear anti-glare film for car windows. I'm not sure of the light transmission of it though. Most of the window tint films will also have a rating of the percentage of light that they let through, 5, 10, 15%, etc. Some will even include a number letting you know how much UV light is let through also. So you may just want to look for an anti-glare film and check the light transmission of it. 

George

George


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## gpodio (Feb 4, 2004)

For photography it would be much easier to simply use a polarizing filter on the lens itself, this way you could easily adjust the filter to reject reflections you want to block out. For example fishing glasses are vertically polarized so they reject horizontal reflections coming off the water, it only works if you're standing up, lie on your side and you get the opposite effect. There is also another factor to consider, polarizing a light source does not give the same effect as polarizing the viewer or camera lens. You can't polarize light and expect it to not reflect off an object, it's the reflected light that becomes polarized depending on the reflection angle, and you can then block that reflected light by using a polarizing filter orientated in the opposite axis. To get the same effect you are after without asking the viewer to wear polarized glasses, you would have to "tint" the front glass of the tank using a polarizing film rejecting horizontally polarized light, which is being reflected off the plants and objects in the tank. I would buy a pair of fishing glasses or camera filter and see what the final result will look like before buying the film. It's definetly a big plus for anyone taking photos of their tanks to have a variable polarizing filter available.

Hope that helps
Giancarlo Podio


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## JamesHoftiezer (Feb 2, 2003)

The reflections on the plants might be a very good reason not to try the top.
The anti-glare could be worth trying onthe front, but I'll have to see how expensive sjsut a small piece of film is.

Here are some examples of general pictures with and without filters;
http://www.cameragear.com/cpl.asp

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## George Willms (Jul 28, 2004)

You can usually find that anti-glare coating in any auto parts store that also sells window tints by the roll. Something like R&S Strauss, Pep Boys, etc. It's usually a couple bucks for a roll.

George


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## gpodio (Feb 4, 2004)

What is the effect you are looking for?

Anti glare will reduce reflections on the glass from your surrounding light sources and objects in the room, much like an anti-glare screen for your computer screen. The nice thing is that a good quality anti-glare filter should block very little light coming from within your tank.

Polarizing filters will reduce the reflections coming from within the tank itself. They will also transmit around 50% of the light for optical grade films, usually less with cheaper grades. You could also look for a partial polarizing filter, something that only blocks say 25% of the light which is off axis, this will half the effect but allow more light to pass the filter overall.

Ideally if you find a polarizing filter with anti-reflection coatings that would give you the best of both worlds. I think you'll find the polarizing film more expensive than anti-glare film. I would also read the specs on the films sold for car windows, many of them do a very poor job to keep the prices down. After all just how much glare do you produce inside your car? Well unless you have a reef tank in the back seat









Hope that helps, here are some links that might be of interest to you:

http://www.scientificsonline.com/EC/Products/Display.cfm?categoryid=192872

http://www.3dlens.com/polarizingfilm.htm

http://www.e-sci.com/Kids/RENDER/1016/2005/3044/11090.html

(sorry for the long links)

Giancarlo Podio


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## George Willms (Jul 28, 2004)

> quote:
> 
> After all just how much glare do you produce inside your car?


Ever seen your dsahboard reflected in your windshield? I'd say that counts as a lot of glare!









George


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## gpodio (Feb 4, 2004)

No but we may drive different cars. My statement was part joke part reality, for the price of window tint you can't expect to get a quality filter, something that you would want to take a photo through anyway. The relatively low amount of light coming from your dashboard can easily be reduced by even the cheapest of anti-glare or even neutral density films, it doesn't take much as usually there is more light outside the car than in. If you have a window behind you while looking into your fish tank the amount of glare is significantly more, that's why I would read the specs (not % of light transmitted) of the films available and choose one with a good anti-reflective coating.

I think I'll go home and give it a try, I have an expensive piece of glass with anti-reflective coatings and also some polarizing filters. Now I'm curious to see what improvement one will make over the other.

Giancarlo Podio


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## JamesHoftiezer (Feb 2, 2003)

Same kind of curiosity got this topic started









I already planned on getting the polarizing filter for the camera. In fact my next camera will be a G3 specifically because I can add filters.

I could use and anti-glare coating but its not as big a deal. Day to day glare isn't an issue and pictures are usually taken with a darkened room.
The polarizing filter would have been interesting but I won't pursue it. At least part of the washout is from reflections and the filter would not help with that. Plus I've learned from this discussion that 50% of the light will be dimmed by adding the filter.

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## gpodio (Feb 4, 2004)

I think you chose the best solution. I tried both last night and took some photos. The anti reflection pane did very little in my opinion. Most of the reflections that were hard to remove were from the inside of the tank. The polarizing filter worked very well but there was no single orientation that improved everything. The filter would have to be rotated depending on the angle of reflection. For example if I rotated the filter to one point I could eliminate most of the reflections from the back glass and depending on the angle of the leaf and the light hitting it I could easily remove any glare or reflection coming off the leaves themselves or other objects in the tank. The overall brightness of the tank was somewhat reduced to around 60-80% depending on the angle of the polarizing filter (this is a high transmission filter, plastic film would block out more light). So in the end the polarizing filter is the way to go but you will want to be able to rotate it depending on what you are photographing at the time. The best results were looking straight down into the tank with the light on, no glare at all from the lights with the filter blocking horizontal reflections. Fishing glasses did the same thing but the lenses on my fishing glasses are cheap ones and the best effect was looking through the good filter. If you are looking to eliminate more reflections coming off at different angles for a single photo you will appreciate what stacking a couple of polarizing filters can do.

If anyone is interested I will post the photos I took last night using the polarizing filters.

Giancarlo Podio

[This message was edited by Giancarlo Podio on Fri June 27 2003 at 10:44 AM.]


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## MarcinB (Apr 16, 2004)

I'm interested!

150L (40G) planted tank
click here for photo


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## JamesHoftiezer (Feb 2, 2003)

It would be great if you could post those. 
If you have some with and without pictures it would be awesome.

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## gpodio (Feb 4, 2004)

I'll develop them tonight and post them. I'm not sure the ones I took without any filter are from the same angle but I think they should still be able to show the difference. I wonder if using selective filters would give any interesting results by rejecting certain wavelengths?

Giancarlo Podio


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## JamesHoftiezer (Feb 2, 2003)

Its possible.
It might pull the greens or reds out better depending on the filters used.

*James Hoftiezer

Tank Journal - Aquascape ( Latest / Archive )
Tank Journal - Parts and Construction ( Latest / Archive )*


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## gpodio (Feb 4, 2004)

Out of the ones that come to mind, perhaps one of the broadband filters I have might be fun trying. It's a light pollution filter:










The only thing is, it tends to give a slight purple tint to the image which would have to be removed manually.

Giancarlo Podio


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## gpodio (Feb 4, 2004)

Sorry about the quality but my home scanner is an antique









Photos

In the first photo I rotated the filter to remove some of the reflections off the back glass. The second instead to remove the glare off the middle section where the lotus is. I didn't take one from the same angle without the filter, it really didn't make much difference however, just didn't have either of the two effects and the image was a little brighter.

There's really so many different orientations that you can't improve the entire tank with just one setting. You improve one thing and lose the effect of another that is reflecting light at a different angle. It works better on closer shots where you can adjust it to enhance a single object like in the last two shots.

I think it would make a great accessory to anyone doing macro work.

Giancarlo Podio


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