# CPL Vs Linear



## Ptyler22 (Apr 13, 2009)

I got a circular polarizer about a couple months ago but what I realized is that I will have to keep constantly adjusting it when I'm out shooting. So I won't be able to use my hood or just shoot shoot shoot, I will have to keep adjusting the filter for every shot.  Do you have to do this with a Linear polarizer or is it always "on" and you don't have to turn it to adjust the polarization. Also do linear polarizers have a "stronger" effect than cpl's?
I'm mostly going to be using it to shoot cars, so there will be lost of different angles and things that I have to adjust the cpl for.

Thanks a lot!


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## tsaraleksi (Apr 13, 2009)

The difference between a linear and a circ is that the circ won't screw up your camera's AF. Otherwise they behave the same with regards to the image. That you have to mess with the polarizer is simply an artifact of physics.


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## AlexColeman (Apr 13, 2009)

Go with Circ when in doubt, then it works with everything.


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## Overread (Apr 13, 2009)

if you want your hood on whilst shooting surf Ebay for some screwfit hoods. Then you can have the hood screw into the front thread of the circularpolarizer and have the best of both worlds. Vignetting (shadows in the corners) should not be a problem with these hoods on a crop sensor camera body and is most likley not a problem for fullframe ones either unless your using very wide angle lenses.


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## Do'Urden's Eyes (Apr 13, 2009)

I've always been told because i shoot digitally i should use a circular, but linear is much cheaper, and if its only because of the auto focus that i need it i can just buy a linear and focus manually? Most of the time i use a polarizer i'll also focus manually.


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## Ptyler22 (Apr 13, 2009)

Oh, ok, sounds like I've got the right one then, thanks guys!


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## c0ps (Apr 13, 2009)

I'm not sure about this but Im gona throw it out here anyway. Why would you need a hood with a Circular filter on? the circular filter prevents glare off subjects and lens.


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## Overread (Apr 14, 2009)

but hoods also protect the lens against a lot of accidental bumps and scrapes. I really hate shooting macro without my lens hood on - so many twigs and such can end up comming into contact with the front element without you even noticing. Sure most of the time its fine - but there is going to be that one rose with that one really sharp thorn oneday!!


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## Ptyler22 (Apr 14, 2009)

Overread said:


> but hoods also protect the lens against a lot of accidental bumps and scrapes. I really hate shooting macro without my lens hood on - so many twigs and such can end up comming into contact with the front element without you even noticing. Sure most of the time its fine - but there is going to be that one rose with that one really sharp thorn oneday!!



Ya exactly, I just want to protect it, I mean $350 lens, and then a $60 filter, I want to protect them plus flare off the lens from the sun still happens with the cpl on


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## c0ps (Apr 14, 2009)

Overread said:


> but hoods also protect the lens against a lot of accidental bumps and scrapes. I really hate shooting macro without my lens hood on - so many twigs and such can end up comming into contact with the front element without you even noticing. Sure most of the time its fine - but there is going to be that one rose with that one really sharp thorn oneday!!


very good point lolI :,s


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## dhilberg (Apr 14, 2009)

Do'Udren's Eyes said:


> I've always been told because i shoot digitally i should use a circular, but linear is much cheaper, and if its only because of the auto focus that i need it i can just buy a linear and focus manually? Most of the time i use a polarizer i'll also focus manually.



It's not about shooting with digital equipment, it's about the AF and metering system in the camera. You can use either type of filter on your SLR, but any camera that has built-in AF and metering will most likely lose one or both of those features because of the way a linear polarizer manipulates the light.

Here's some more in depth polarizer information:

Polarizers
Polarizer - Camerapedia.org


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## EhJsNe (Apr 14, 2009)

Its the lens focusing and its rotating the filter.

Get a lens with Internal Focusing and you wont need to reajust your filter.


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## Ptyler22 (Apr 15, 2009)

EhJsNe said:


> Its the lens focusing and its rotating the filter.
> 
> Get a lens with Internal Focusing and you wont need to reajust your filter.



My lens does have internal focussing but for different angles of reflection and when shooting portrait, vs. landscape, won't I have to adjust the filter?


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## EhJsNe (Apr 15, 2009)

Ptyler22 said:


> My lens does have internal focussing but for different angles of reflection and when shooting portrait, vs. landscape, won't I have to adjust the filter?


 
Yes you would....I didnt even think of that. 

Maybe someone should invent an automatic rotating polarizing filter to automaticly reduce glare......


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## dcclark (Apr 15, 2009)

EhJsNe said:


> Yes you would....I didnt even think of that.
> 
> Maybe someone should invent an automatic rotating polarizing filter to automaticly reduce glare......



Heh... I think you're just plain out of luck. After all -- sometimes you want to use the polarizer to reduce glare. Some times you want to intensify colors (enbluening the sky, for example -- what a great word). Sometimes you want to absorb some light (I've done that a few times if I forgot my ND). An automatic filter would have to read your mind to determine your intent for a photo!


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## Ptyler22 (Apr 15, 2009)

Or they could have a polarizer that didn't need rotating at all, I don't know it they could do that by like "overlapping the polarization" if that makes sense, it would be awesome if they could do that. I'd buy one!


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## Overread (Apr 15, 2009)

Coken (SP) filters and a filter holder would do that job - not attached to the lens at all, but on a filter holder so the lens can rotate all it wants, the filter will remain in the same position.

However as dcclark said sometimes you want a different effect for a different shot so you need that rotating abilty in order to be able to set the polarizer to the right setting


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## Dwig (Apr 15, 2009)

Ptyler22 said:


> Or they could have a polarizer that didn't need rotating at all...



Not possible at all. The basic nature of the physics that makes polarizers effective mandates that the have an orientation and that that orientation must be set specificly relative to the light that you intend to block.


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