Filter Question

[chammer]

thank you very much, plato! so if im getting it correctly, even though i cant see these little circles that are depolarizing the light...they are angled in some direction and rotating the filter is changing the direction of these and thus increasing or decreasing the depolarized effect?

 

[phifer8390]

Here's another tip for CPL filters. DO NOT CHEAP OUT!

Anything under $50, I would pass on. Really IMO, from $80-200 range you are more likely to get a quality filter.

Popular brands: B+W (probaly one of the best), Singh-Ray (perhaps a little better), Hoya, Tiffen, .... there's a couple more but they elude me at the moment. The wine, the wine.......

So what your saying is my Tristar filters are pretty much crap!

 

[Plato]

The CPL filter is most effective when at 90° from the light source (sun).

Two excersizes to test the effectiveness.
1) On a nice sunny day with white puffy clouds in the sky turn so that you're 90° from the sun. Point your lens towards the clouds.... look through the viewfinder. Slowlyy rotate the outer ring of the filter and take note of the change/contrast the clouds have as well as the blue color of the sky. See any change?

2) On a nice sunny day go out to your car, turn so that you're 90° from the sun. Point your lens towards your windshield. Slowly rotate the outer ring of the filter and take note of the change of reflection from "I can't see anything but the reflection" to "Hey, I can see the interior of my car. It really needs to be cleaned up".

The CPL filter reduces reflections, increases contrast and increases saturation (particularly blue & green).

Outside, I usually like to have it on. If the effect is more than I want.... rotate it. Have fun.

Ok this is all making more sense now - thanks kundalini and Plato. That brings me to another question then . Lets say I'm outside taking photo's of people. If I follow the be 90° from the sun thought, then wouldn't that also put the people whose photo's I'm taking with 1/2 of their face in the shade?

No. First, the polarizer blocks all frisbees oriented in the same direction BUT these frisbees are uniformly distributed over the entire image so you'll slightly reduce the light hitting the entire face. Second, human skin doesn't reflect much so it wouldn't have much effect on the faces. It will, however, darken the sky behind them.

 

[kundalini]

, then wouldn't that also put the people whose photo's I'm taking with 1/2 of their face in the shade?

If they're standing half in the sun and half in the shade, then you as the photographer will tell them to move. In or out, preferably in the shade.

The CPL will not half shade them.

 

[kundalini]

So what your saying is my Tristar filters are pretty much crap!

Filters 101 by Thom Hogan.

 

[Plato]

thank you very much, plato! so if im getting it correctly, even though i cant see these little circles that are depolarizing the light...they are angled in some direction and rotating the filter is changing the direction of these and thus increasing or decreasing the depolarized effect?

Yep. You can't see the circles just like you can't see the venetian blinds. And nope. The rotation affects the venetian blinds on the front surface of the filter. It has no effect on the back side of the filter. Regardless of how much you're polarizing the light, you're always depolarizing 100%.

I do suggest that you avoid over-analyzing. Stick with the analogy and combine that with what you've experienced while experimenting with the polarizers.

 

[Plato]

So what your saying is my Tristar filters are pretty much crap!

Filters 101 by Thom Hogan.

I am a firm believer in always getting the best filters that I can afford. Consider that you're adding two surfaces, two flat surfaces, to the light path. In addition to whatever good things the filter will do for you, it will always degrade the image somewhat. With good quality multi-coated filters, the degradation is insignificant. With cheap filters, you might as well be shooting with an Instamatic (or, in today's semantics, a cheap digital P&S).

 

[thenikonguy]

wow.. i go away for a few hours, and come back to 3 pages of answers!! nice. guess i have alot of reading to do tonight! thanks for all the info people!!

 

[chammer]

I do suggest that you avoid over-analyzing. Stick with the analogy and combine that with what you've experienced while experimenting with the polarizers.

hehe yea, but im the type of person that likes to know why they are doing something instead of just "ok, to do this i need to do that". its how i learned computers inside and out since 1994, and its how i do pretty much with anything i pick up.

i believe someone posted this here, and it was one of the first things i tried when getting my cpl...but if you put it on your lens and point your camera towards your lcd monitor then rotate the cpl...you can see the lcd go from normal to just about pitch black. i thought that was really neat and i just want/wanted to understand how it did that because i couldnt see any physical difference on the surface of the cpl. thats what prompted my curiosity, but i just kept forgetting to post about my question until i saw someone else post it.

 

[kundalini]

I am a firm believer in always getting the best filters that I can afford.

Too right. Here's an example folks. I have 4x 77mm lenses. Let's ball park the total cost of those at $5400 (+ tax and before Nikon's price rise). So I spend $200 on a CPL What's the actual cost? .04% of my lens cost. I spent $150 on a 62mm CPL filter, but I have 3x lenses at ~$2000 that I can use it on. That works out to .08% of my lens cost.

There is a method to my madness.

Of course, I'm not an accountant, I don't play one on TV either and I would strongly urge you to consult one for your own particular situation.

 

[Bitter Jeweler]

Couldn't you have bought a 62mm to 77mm converter thing?

 

[kundalini]

Yes. But I like using my lens hoods.

Oh... and looking like a dork with professional equipment isn't my MO.

 

[shortpballer]

The best way to see how this works exactly is to look at water. Then slowly turn your polarizer and you will notice that once turned to a certain point the light will not reflect at all and the water will be clear ( considering that its clear in the first place) Basically all the reflections will go away. Pretty cool I know. I was amazed in the beginning as well. Like the frisby example

 

[kundalini]

shortballer, I suggest you read through the thread before just jumping in with your own 2¢. Been there, done that, we've moved on.

 

[Plato]

I do suggest that you avoid over-analyzing. Stick with the analogy and combine that with what you've experienced while experimenting with the polarizers.

hehe yea, but im the type of person that likes to know why they are doing something instead of just "ok, to do this i need to do that". its how i learned computers inside and out since 1994, and its how i do pretty much with anything i pick up.

i believe someone posted this here, and it was one of the first things i tried when getting my cpl...but if you put it on your lens and point your camera towards your lcd monitor then rotate the cpl...you can see the lcd go from normal to just about pitch black. i thought that was really neat and i just want/wanted to understand how it did that because i couldnt see any physical difference on the surface of the cpl. thats what prompted my curiosity, but i just kept forgetting to post about my question until i saw someone else post it.

I understand. I'm a bit like that myself. However, don't let your interest in details cloud your ability to make photographs. Think of your computer comment. Knowledge of computer internals doesn't help you use Lightroom.