What oes a polarizer filter do?

[prodigy2k7]

Would a polarizer be bad for indoor portrait shots? it seems to darken the image a little, leading to slight underexposure...

In my personal experience its mostly good for outdoors only??

can anyone comment plz?

 

[Miaow]

Would a polarizer be bad for indoor portrait shots? it seems to darken the image a little, leading to slight underexposure...

In my personal experience its mostly good for outdoors only??

can anyone comment plz?

As Garbz mentioned earlier in regards to funny things that can happen

In the right circumstance it can make a person look like they are made of clay.

I believe they are more an outdoor/landscape filter - I don't see one why you'd need to use on on an indoor shot really? Though I just found something on the net on a warm polarizaer though i think again that may be for outdoors also (not sure)

 

[TamiyaGuy]

photos

Wow, those are some great examples, Mav! Looking at those photos, can a polariser also help skies become more balanced to the foreground? i.e. making the sky look blue as compared to sheer white.

 

[Ben-71]

[/left]
Wow, really? How does that happen?

The polarizing effect is at its maximum when the lens is perpendicular to the sun.
The effect is gradually reduced as the lens is panned towards - or away from - the sun.
With the sun in front of - or behind - the lens, the polarizing effect is zero.

e.g.:
A 14mm lens is perpendicular to the sun.
Having an an angle of view 114 degrees, at the sides, the lens 'looks' at an agle that is 57 degrees from perpendicular, relative to the sun.
This angle is far enough from perpendicular, to considerably reduce the polarizing effect, so we get the polarizing effect in front of the lens, and very little of it at the sides of the photograph.
If we have the sky across the frame from side to side, the middle will be darker blue, the sides will be brighter and whiter.

 

[andrew99]

Mav - great post! One example where a picture actually is worth a thousand words!

 

[K8-90]

[/left]
Wow, really? How does that happen?

The polarizing effect is at its maximum when the lens is perpendicular to the sun.
The effect is gradually reduced as the lens is panned towards - or away from - the sun.
With the sun in front of - or behind - the lens, the polarizing effect is zero.

e.g.:
A 14mm lens is perpendicular to the sun.
Having an an angle of view 114 degrees, at the sides, the lens 'looks' at an agle that is 57 degrees from perpendicular, relative to the sun.
This angle is far enough from perpendicular, to considerably reduce the polarizing effect, so we get the polarizing effect in front of the lens, and very little of it at the sides of the photograph.
If we have the sky across the frame from side to side, the middle will be darker blue, the sides will be brighter and whiter.

Thanks, that makes sense :thumbup:

 

[davebmck]

With a very wide lens, the polarizing effect will be only at part of the pic' (or part of the sky), which typically looks bad.

I was thinking of getting a circular polarizer for my Sigma 10-20. Does the above quote mean this would give bad results? Do others here agree with this opinion?

 

[RKW3]

I was thinking of getting a circular polarizer for my Sigma 10-20. Does the above quote mean this would give bad results? Do others here agree with this opinion?

You will get strong, probably untasteful vignetting and uneveness. I've experienced this personally at 18mm, which isn't even that wide. I don't think it's worth it for a wide angle lens such as the 10-20.

An example:

That's a bit dramatised, but that's pretty much what can happen if you put a polarizer on a wide angle lens.

 

[davebmck]

Thanks, I'll save my money.

 

[Early]

Ok, I guess if the answer is "it is crap", then my question would be is it crap for an expensive dSLR, or would it also be the same crap if you were using a cheap $200 superzoom?

Tiffen isn't crap. Far from it! It will rarely blemish or get stuck on your lenses like some of the other lower cost filters on the market.

 

[adamodepax]

x

 

[Valethar]

90 degrees is a right angle. Think of square room. Each time you come to a corner, the wall makes a 90 degree turn. The same thing is true for perpendicular, which is a right angle, though it doesn't always have to be a full 90 degrees if I recall.

If you're taking a picture of someone standing in front of you, at 12:00 in the afternoon, the sun would be perpendicular, or approximately 90 degrees from the direction your lens is pointed.

 

[adamodepax]

x

 

[Ben-71]

<< After reading most of the posts, I'm glad that I understand a lot, but there is something I'm having trouble picturing. Can someone maybe draw what is meant by 90 degrees from the sun? Or perpendicular? Does that mean you are directly under it? I'm OK at math but I just can't picture it... >>

Let's say that the sun is low, at the east.
If you point the camera to the north, or to the south, the lens is perpendicular to the sun, or, in other words - at 90 deg. to the sun.

Draw a circle. You're at the center. The sun is on the right side of the circle (=east).
The top of the circle would be north, and the bottom would be south.

If you first point at the direction of the sun (which is at the east in this example), you'll have to turn one quarter of the circle away from it (which is 90 deg.).
If you turned left, You'll now point to the north. If you turned right, you'll now point to the south.
Either way, you now point perpendicularly to the sun - and get the maximum effect of the Polarizing filter.

I hope this makes it clearer.

 

[Ben-71]

Now I see that my reply wasn't necessary...