The polarizer effect is one of the most common ways to reduce glare from light sources such as sunlight or moonlight. A polarizing filter prevents certain wavelengths of light (such as blue) from entering your eyes while allowing other wavelengths through. By blocking out some of these longer wavelength rays, it reduces the amount of heat energy being radiated back into space and therefore helps cool down your computer, TV set, etc..
What’s so great about a polarizing filter?
Well, let’s say you’re outside in the sun and looking at the sky. You could use sunglasses or even prescription glasses to block out all but the shortest wavelengths of light.
But what if instead of using those methods, you wanted to make sure only the reds and oranges were visible?
That would mean wearing a polarized lens!
A polarizing filter is simply a piece of plastic with two prongs attached to it. One prong is used to direct incoming light toward the eye, while the other directs it away from your eyes. When you put them together, they create a prism which reflects some of the light and blocks out others. The result is that certain colors are blocked out completely while others pass through without being reflected back.
Here’s the secret formula. Let’s say our incoming light is composed of mostly red, green, and blue wavelengths. A polarizing filter will block out all of the red and green but allow the blue to pass through to your eye. The amount of each color that passes through is determined by how the filter is positioned relative the sun or other light source.
The advantage of using a polarizing filter over things like sunglasses or prescription lenses is that they don’t alter the color of what you’re looking at. If you’re trying to take a picture of something and want only blue light to pass through, then your camera will pick up more than it would otherwise.
A polarizing filter can also have the effect of darkening certain parts of an image. Again, this is because it’s not actually blocking out the light that’s coming in from those areas, but instead reflecting it back so that it doesn’t reach your eye.
Are there any other advantages?
Well, they can also cut down on glare and reflection when looking at things that are wet such as a pond or a mirror. Some people even use them for fashion. The darkening effect they have can also help in reducing eye strain while reading.
But if you have the money to throw around and don’t care about the effect they have on your eyes, you might as well spend it on something with more benefit right?
There’s a reason why most people don’t bother with these things and it has nothing to do with looking good.
The real issue with polarizing filters is that they reflect light more than regular lenses do. This can actually make things harder to see when you’re outside on a sunny day. It’s a common misconception that they reduce the amount of light coming into your eyes, but in reality, the darkness is only relative to how much incoming light is being reflected away.
You might find it easier to see things under a shade tree or possibly using a hooded sweatshirt to cut down on the glare. As I’ve mentioned before, polarizing filters can be great for cutting down on reflection, but not so much for blocking incoming light. So unless you live in a rural area where there’s plenty of shade trees, you might not find much use for such a filter.
Finally, they aren’t cheap. I’m not just talking about how much money you have to spend on one either. Even if you manage to get a good deal on one at a yard sale or something, getting the lens itself can be difficult.
Polarizing lenses are very hard to make and it’s very easy to damage them as well. There was a time when camera stores actually had people cut lenses for you, but those days are long gone mainly because the cost of raw materials has skyrocketed.
Even if you did manage to get one at the right price, you’d probably be paying more than what it’s actually worth. Even used ones go for three hundred dollars and up on websites like eBay.
So if you do decide that a polarizing filter is right for you, then you’ll have to do a little leg work in finding one at the right price or settling for one that isn’t exactly brand new.
In any case, that’s about it for this lesson. Remember, the best camera in the world isn’t going to take a good picture if you don’t know what you’re doing, but at least now you’ll be able to get better quality images in most situations.
Continue on to the next section to see a demonstration on how these filters work.
Sources & references used in this article:
Polarized lens with oxide additive by CP Larson – US Patent 6,334,680, 2002 – Google Patents
Polarized lens with oxide additive by CP Larson – US Patent 6,604,824, 2003 – Google Patents
Survey of demosaicking methods for polarization filter array images by S Mihoubi, PJ Lapray, L Bigué – Sensors, 2018 – mdpi.com
Color-enhancing polarized lens by MJ Farwig – US Patent 6,145,984, 2000 – Google Patents
A new quasi-optical filter: the reflective polarizing interferometer by NR Erickson – International journal of infrared and millimeter waves, 1987 – Springer
Deep subsurface imaging in tissues using spectral and polarization filtering by SG Demos, HB Radousky, RR Alfano – Optics Express, 2000 – osapublishing.org
Ultraviolet radiation and blue light blocking polarizing lens by LA Johansen, P Diffendaffer – US Patent 4,878,748, 1989 – Google Patents
Polarized light examination and photography of the skin by RR Anderson – Archives of dermatology, 1991 – jamanetwork.com