what does a polarizer filter do?

Question

what objects do you use it on?

holy crap @ all the answers I've gotten ! OH!

i'm talking about for the telescope not camera's by the way

Answer 1

The polarizer filter used in astronomy is actually a crossed polarizer filter: a pair of polarizer filters where one rotates relative to the other. This acts as a "dimmer switch" on bright objects like the Moon and Mars. By cutting the glare from these objects, it becomes easier to see subtle shadings on them. Rotating one filter causes the light passing through to go from white to black, so you can adjust the brightness precisely.

Answer 2

Light is a wave, and its oscillations are transversal - like those of a string (piano, violin, guitar, etc.) A direction of such an oscillation is called polarization.

A polarizer filter lets light pass only if light oscillations are in the direction of the filter - like a jumping chord you make oscillate through a post fence. In the latter case, only the part of the oscillation that is along the posts will pass.

Light is made of oscillations of all directions, so if you use a polarizing filter to lookat a light bulb you won't notice any difference when you rotate the filter - except that the light is dimmer (only half of it passes). If you look at the clear sky, about 90 degrees (perpendicular) from the Sun and rotate the filter, you'll notice that the intensity of the light passing through the filter changes when you rotate the filter. This happens because the light from the sky is partly polarized (the maximum polarization is perpendicular to the direction to the Sun).

In astronomy, polarizing filters are used for two purposes:
1. As variable density neutral filter: just stack two polarizers ontop of each other, and look at a light source while rotating the filters with respect to each other. When the filters are aligned, most of the light passes - in theory, all the light passing through the first filter will also pass through the second, so the maximum transmission through both filters is 50%. In practice, there are additional losses in the filters, so most stacked filters do not pass more than 40%.
When the orientation of the filters is perpendicular to each other, in theory there should be no light passing through. In practice, filters are not perfect, so there wwill be some light passing, typically 1% or less.
2. Some nebulas nebulas reflect light much like the sky reflects light from the Sun - the light is partly polarized. By rotating the filter, you can find the direction of this polarization. (actually, it is a little more complicated - the polarization of light from nebulas is linked to the magnetic fields in the area)

For terrestrial use, light reflected from various surfaces is partly polarized, because light with different polarizations is reflected with a different intensity. As such, a polarizing filter can be used to reduce reflections (if rotated properly - you just rotate the filter until you get the result). Since stray light from reflections (partly polarized) is reduced, at the proper filter orientation colors may appear more saturated.

Answer 3

A polarizer is a device that converts an unpolarized or mixed-polarization beam of electromagnetic waves (e.g., light) into a beam with a single polarization state (usually, a single linear polarization). Polarizers are used in many optical techniques and instruments, and polarizing filters find applications in photography and liquid crystal display technology.

Answer 4

I remember being taught about polarisation in physics at school. It is a way of filtering light. The oscillations of the EM wave occur in all directions. A polariser only allows oscillations in a certain direction (ie "up-down") through it. Therefore a lot of light is blocked while only a small amount is let through. This is the theory behind polarised sunglasses.

Answer 5

Hi. It allows light with waves that are roughly lined up to pass while blocking light that is roughly 90 degrees turned. Useful in photography and the study of magnetic fields in space.

Answer 6

Consider that your sun shades are polarized is like a venetian blind that will let the sign waves through the blind that go in one direction.

Answer 7

I use it on still and video cameras. It reduces glare from the sun. It makes colors pop a little too.

Answer 8

In photography it removes reflections that can result from the sun reflecting of various surfaces.

Answer 9

Grey, black and brown bears seem to come out white in the photos.

Answer 10

dunno