UV vs Polarized filter

[JonZenor]

Hey everyone, I'm completely new to photography and to this forum. I bought a UV and a Polarized filter for my camera, and am wondering when I should use each one?

I have heard some people say they keep their UV filter on the lens at all times, others say they keep the polarized lens on all the time, and others I have heard say they never use filters.

From what research I have done it looks like I should keep the UV filter on most of the time (to help protect the lens) and use the polarized filter on sunny days to help get rid of glare and make the color of objects stand out more.

So which is it?

[WVCoalMiner]

Originally Posted by JonZenor

From what research I have done it looks like I should keep the UV filter on most of the time (to help protect the lens) and use the polarized filter on sunny days to help get rid of glare and make the color of objects stand out more.

So which is it?

That's it... Good job researching LOL
You normally don't want to use the polarized filter in low light/indoor shots because you lose (I think) 2 stops of your aperture so it will make your shutter speed slower.

[OsmosisStudios]

Do me a favour: if you ever meet someone that tells you to keep a polarizer on your lens AT ALL TIMES, hit them. Hard. Thanks.

The UV filter is generally used on the lens at all times: on a DSLR it has no effect and is being used to protect the front element of the lens. It's a tendentious argument, so I wont get into it. I use one ONLY when i think the lens may get dirty or damaged (photojourno, mainly). It's easier to clean/replace a filter than a lens.

Polarizers darken the sky and reduce reflections and glare from NON-METALLIC objects (glass and water, mainly). They absorb 2 stops of light, too, which is why you dont necessarilly want them on your camera at all times.

If you got a LINEAR polarizer (the front doesnt spin) you need to return it: it's useless on digital.

[zona5101]

Originally Posted by JonZenor

Hey everyone, I'm completely new to photography and to this forum. I bought a UV and a Polarized filter for my camera, and am wondering when I should use each one?

I have heard some people say they keep their UV filter on the lens at all times, others say they keep the polarized lens on all the time, and others I have heard say they never use filters.

From what research I have done it looks like I should keep the UV filter on most of the time (to help protect the lens) and use the polarized filter on sunny days to help get rid of glare and make the color of objects stand out more.

So which is it?

pretty much what you wrote in the last paragraph!

[JonZenor]

Thanks for the information everyone

The polarized lens I have is circular.

[Doug Pardee]

Originally Posted by OsmosisStudios

If you got a LINEAR polarizer (the front doesnt spin)

The front of a linear polarizer spins the same as on a circular polarizer. The difference between the two is that in a circular polarizer there is a quarter-wave plate to depolarize the light that comes out from the filter.

it's useless on digital.

"Useless" is a strong word, and the distinction isn't "digital", it's "autofocus SLR".

In SLRs and DSLRs, the (pretty much universal) approach to autofocus involves making the viewing mirror be half-silvered, or what is technically called a beam-splitter. Part of the light coming in from the lens is reflected up to the focus screen, while the rest passes through and is sent to the AF detectors.

In SLRs and DSLRs, the (pretty much universal) approach to in-camera metering is to measure the brightness of the image that is projected onto the focus screen. For autofocus SLRs and DSLRs, this requires that the percentage of light reflected by the viewing mirror be constant and known. For Canon SLRs and DSLRs, 60% goes to the viewscreen and 40% to the AF detectors.

Beam-splitters reflect a different percentage of the incoming light depending on the polarization of that light. With a linear polarizer, the light reaching the beam-splitter (viewing mirror) is still polarized, and the direction of the polarization depends on how you have the filter adjusted.

So you see the problem: adjusting the linear polarizing filter will change the percentage of light reflected to the viewscreen, which in turn will affect the in-camera metering.

But! The difference in the percentage that gets reflected is fairly low for beam-splitters built using an aluminum reflective coating, which is pretty much every SLR or DSLR beam-splitter ever made. It's probably less than 1/3 stop in most cases. Most people will never notice this difference.

So: for autofocus SLRs and DSLRs, the circular polarizer is in theory the correct choice. However, in practice a linear polarizer will probably work just fine. I've seen many postings from people using linear polarizers on their autofocus DSLRs, and none have reported any noticeable problems.