What is a CPL (Circular Polarizer) and How Does it Work?

[Peisqo]

Hey guys ... i've recently got my HOYA CPL filter ... i have to admit i have little knowledge about filter :( I only know that it reduces flash reflects and serve to protect my lens ... so at first i planned to get the cheapest UV filter ... but when i was browsing tru ebay .. i've found an even cheaper CPL .. so i was like "why not?" ... so today it came ..

I notice at the end there is an adjustable ring ... what is it for ? I've tried moving it around .. nothing changes ... except when i point the camera to my monitor ... then turn the ring .. the glow in my monitor changes :P

So question is ... who knows the real function of that ring ? And also .. will the CPL filter, in ANY condition worsen the picture ? As in is it safe if i keep it attached to my lens ALL the time ? Thanks !! :)

[ShaolinTiger]

I wonder why you bought a CPL when you don't really know what it's for!

CPL is not used to protect lens!

CPL is to polarize the light that enters your camera during exposure, this means that it will cut down on atmosphere reflections and hazy effects caused by humidity.

The humidity and water particles in the air reflect light and reduce contrast.

It helps give you rich blue skies and more vivid greenery in landscape pictures.

Like these shot with 77mm B+W CPL.

http://farm1.static.flickr.com/223/482761454_4709dedc75.jpg

http://farm1.static.flickr.com/227/494511842_06b4052a95.jpg

http://farm2.static.flickr.com/1151/527685996_8107515fe9.jpg

Also note that it will lengthen your exposure and usually had 2-3 stops effect.

It's not recommended to have it on at all times, if you want to use a filter to protect your lens you should get a UV filter.

I recommend the Hoya Pro1D range.

The ring that moves when you twist it changes the effect of the polarization, basically it adjusts the degree.

A polarizer works best when your camera is pointed perpendicular to the sun (at a 90 degree angle).

I suggest you go out around 3-4pm, face 90 degrees away from the sun, point your camera at the sky and twist the ring on the polarizer.

You should see the changing effects in the viewfinder.

[Peisqo]

I wonder why you bought a CPL when you don't really know what it's for!

CPL is not used to protect lens!

CPL is to polarize the light that enters your camera during exposure, this means that it will cut down on atmosphere reflections and hazy effects caused by humidity.

The humidity and water particles in the air reflect light and reduce contrast.

It helps give you rich blue skies and more vivid greenery in landscape pictures.

Like these shot with 77mm B+W CPL.

http://farm1.static.flickr.com/223/482761454_4709dedc75.jpg

http://farm1.static.flickr.com/227/494511842_06b4052a95.jpg

http://farm2.static.flickr.com/1151/527685996_8107515fe9.jpg

Also note that it will lengthen your exposure and usually had 2-3 stops effect.

It's not recommended to have it on at all times, if you want to use a filter to protect your lens you should get a UV filter.

I recommend the Hoya Pro1D range.

The ring that moves when you twist it changes the effect of the polarization, basically it adjusts the degree.

A polarizer works best when your camera is pointed perpendicular to the sun (at a 90 degree angle).

I suggest you go out around 3-4pm, face 90 degrees away from the sun, point your camera at the sky and twist the ring on the polarizer.

You should see the changing effects in the viewfinder.


ahhh thanks for the explanation :P ... ya i know it's dumb haha .. my primary aim is to protect my lens ... but UV filter was about 10 dollars in ebay .. and tat CPL was like 12 bux or something .. so i was like why not :P I've read about reducing the haze and stuff ...

Can u tell me in what condition that a CPL would worsen a picture ? In the dark ? Night pictures ?

[sub7]

About to make decision buying ND or CPL, after reading this review... I'm going to get ND!

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00A3TS

[RobertNikon]

nice shoot and nice and simple explanation

[ShaolinTiger]

About to make decision buying ND or CPL, after reading this review... I'm going to get ND!

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00A3TS

ND won't give the effect of a CPL at all, it just makes your exposure longer.

It's Neutral.

Everyone should own 2 filters, ND Grad and CPL.

[rae128]

Can u tell me in what condition that a CPL would worsen a picture ? In the dark ? Night pictures ?

CPL will reduce a reflection(u have to turn d ring)... for e.g light reflection on the water (whether its indoor or outdoor), reflection of the sun on a leaf or a car window.. etc... so there is no limitation in taking photo whether its in dark or bright situation.. it is a matter of what subject u want to shoot.... and avoid taking picture of people using CPL... i remember one of the post before but i couldnt locate it.. but im sure someone will heheh... where the guy shoot a people with CPL and the people in the picture turn purple... (mostly on the hair.. and part of the face).. Sifus.. correct me if im wrong.. :)

i found it.. here it is... http://www.shutterasia.com/forum/showthread.php?t=3569

[ckchowov]

Just for sharing:). Some test shots after i bought my Hoya CPL, last year(Dec2006).
1. Without CPL
9137

2. With CPL. Please notice tat the CPL has remove the harsh reflection away from the grass field, and the sky is more blue. (the dark upper left corner was my finger;))
9138

[SooHK]

Talking about CPL, a comment by shaolin at my photo blog prompt me to buy one.. hahaha not sure shaolin remembers it or not, that where my love with CPL starts. Starts with a cheap one then now all is hoya pro 1, hahaha.

As I was in rush for my holiday in melbourne, so I did not really try it out in Malaysia and it was just after 3 -4 weeks I got my 1st DLSR (canon 400D). I remember when I was in melbourne I even took a night scene with CPL.... hahaha

http://farm1.static.flickr.com/167/416249449_f46c16de59.jpg

But after that I have never use CPL on any nightscene, as it reduce around 3 stops and it does not really enhance much... so for people like me who never use any tripod, its better to keep it in the cam bag for night scene.

And do not overdo it with CPL too...imho the best is to take it with some clouds. Below taken using Hoya Pro 1.

http://farm1.static.flickr.com/125/375426695_f07070161d_o.jpg

http://farm2.static.flickr.com/1092/861770144_adfc9a05a3.jpg

http://farm2.static.flickr.com/1033/827109795_9193aebab0.jpg

As I have once overuse it the skies looks like pure dark blue.....sorry could not show you one, will need dig into my external hdd to find it...

And if you take botanical landscape on a hot day with lots of greens, reds like those autumn colors, its better to have CPL as without it the pic will sees a lot of unwanted reflection and blown highlights.

And you need to practice with it then you will know when is the best time and situation to use it.

And a caution if you are going on a holiday with your spouse or family...keep it in the bag too hahaha as you are on holiday enjoying with the family not you are on a holiday enjoying yourself taking photographs and changing filters . Unless the weather is predictable in favour of using CPL then its ok. Else you ended up changing CPL and UV/protector filter and loss your family among the crowds.... hahaha

And its best to buy the expensive one too....its does makes a difference...else like me ended buying it more than once...

The above is just my experience in using CPL, others might have their own stories to tell... :)

[adyzul]

Can we use a CPL filter on top of a UV filter?

[noruazumi]

Can we use a CPL filter on top of a UV filter?

can... but if it is not the slim version, it'll create "vignetting".

[Freaky]

best not to stack filters

[ShaolinTiger]

Yah you can stack but it's not recommended, on a wide lens you'll get vignetting (light loss at the corners).

[adyzul]

Thanks for the comments.

The reason I asked is because I used to use other filters on top of my UV filter when using my flim slr before.

[SooHK]

not advisable, have not tried it before but probably might degrade the quality of the pic, as in theory the light goes through another layer, hence some even do not use filter. U can try it out with a UV filter and any mode that set exposure auto. Takes a pic with and without the filter, set the focus at same point in both instances and check the exposure after each shot, I believe there is a bit of differrent...And on the field this probably translate to the need of bumping up the ISO for handheld shot... I once tried it out with a cheap UV filter and an expensive one....after that I never look at cheap UV filter anymore...

[oneOZ]

Wow, love the effect by CPL filter.

BTW, is there any specific CPL filter brand i can purchase for 350D kit lens?

[SooHK]

Hi OneOZ, check shaolin post that contains his sample...thanks..


I recommend the Hoya Pro1D range.

[oneOZ]

Oh cool...

So, what is the normal market price?

[newdaddy]

dear all, this is my first time shooting blue sky with my newly bought CPL filter. Though the sky looks more blue but I still find it not so nice when I compare to the sifu's image here, like something is lack but I not sure what..
I use ISO100, 1/125, f11, 400d with tammy 17-50mm 2.8 at 50mm.
during RAW coversion I set WB to daylight, pic style to landscape, contrast +2, saturation +1, tone curve mk it abit like ''S" shape. After convert to JPej I found the cloud not sharp so I use unsharp mask set to 150%.
Pls comment on how I can mk it looks better. Thx:)

[dinduboy14]

hi gurus,

more questions:

1) what is considered a cheap UV or CP filter?
the Standard HOYA 72mm CP Filter and and Standard HOYA UV Filter?

2) It is mentioned that if its a slim filter, its ok to stack the filters? What type filters are these? :?

3) Besides getting vignetting for wide lens, are there any other downfalls in stacking up filters?

Thanks all!

[nfariz8]

can anyone explain further the difference between CPL and a PL filter? circular and non circular..

[SooHK]

Hi OneOZ, I am not sure the market price in KL but you can get a Hoya Pro CPL digital 77mm at around Rm250 to Rm290 after discount from bangkok.

Hi Newdaddy, CPL will not help in all situation. I believe somewhere up this thread someone explain the theory in how to use CPL, such as subject 90 degree and etc but I believe nothing beats experience. And it also depends on the quality of your CPL filter. Lets hear from the sifu, as I also a year plus Dslr user only.. :)

Hi Dinduboy, yeah that is lowest price Hoya product, try using the pro 1 D model.. answer to ur question 2 and 3 on stacking of filter, I believe answer is found somewhere above this thread...

hi nfariz, I believe PL is more effective but not all camera can use one as compare with a CPL. Try google it for some "textbook" answer, as I remember I saw one last time...

[Peisqo]

can anyone explain further the difference between CPL and a PL filter? circular and non circular..

I read b4 LOOOOOOONGG time ago .. IF memory didnt fail me .. i think CPL is for DSLR and PL is for film camera .. something like tat .. can't confirm 100% .. but asalkan DSLR uses CPL then it's correct la ...

U can simply juz do a google search ull get the answer

[nfariz8]

hi nfariz, I believe PL is more effective but not all camera can use one as compare with a CPL. Try google it for some "textbook" answer, as I remember I saw one last time...

I read b4 LOOOOOOONGG time ago .. IF memory didnt fail me .. i think CPL is for DSLR and PL is for film camera .. something like tat .. can't confirm 100% .. but asalkan DSLR uses CPL then it's correct la ...

U can simply juz do a google search ull get the answer

result from googling said that PL is cleaner due to lesser layer of i don't know what than the CPL but its true about the new DSLR having compatibility problem with the PL.. it either give problem on AF or metering is read wrongly but not on all cameras.. as long as your camera don't have these two problems than you can use both.. there are other details which i think is less important.. :D

[ShaolinTiger]

Yeah it's linear vs circular polarizers, due to sensor makeup circular polarizer are recommended for use with digital SLR.

Linear are fine with film cameras.

[Alan]

Later generations of film cameras are said to have sensitive AF and metering systems that could be affected by linear polarizers. I remember that many of them recommend the use of circular polarizers for that reason. It would be the safest to use a circular polarizers on film cameras too.

[jassed]

My current lenses are the kit 18-55, 55-200, and 50mm 1.8. Cheap lenses... i'm impressed by what a cpl can do, but get doubts because of my lenses (i know fitting cpl on the kit lens is a pain in the arse). Should i get a cpl for any of my lenses?

[ShaolinTiger]

Get a 77mm CPL and step up rings for your lenses.

[jassed]

thanks, any shops selling the rings?

[ShaolinTiger]

thanks, any shops selling the rings?

You can buy them from our own mitmivec here.

http://www.shutterasia.com/forum/showthread.php?t=2663

[dinduboy14]

"Get a 77mm CPL and step up rings for your lenses."

Wouldn't it be cheaper to get 72mm CPL and get step down rings for your lenses? :?:? (sorry newbie here. *dumb question* am i losing the plot??)

[ShaolinTiger]

"Get a 77mm CPL and step up rings for your lenses."

Wouldn't it be cheaper to get 72mm CPL and get step down rings for your lenses? :?:? (sorry newbie here. *dumb question* am i losing the plot??)

Then what happens later when you buy a lens that has 77mm filter size?

[jassed]

Yeah, makes sense to get a 77. For me, its because eventually i'll get the 70-200 2.8. So, better to get a nice 77mm filter plus the step ups and then use it on other lenses.

[Peisqo]

Hmm since alot ppl are asking about the CPL ring .. decided to take this 2 pics to show everyone the difference ... both straight out from camera and both same settings ... notice the water's reflection

http://img20.imageshack.us/img20/6409/cpleffectxx5.jpg (http://imageshack.us)

[jassed]

recently bought myself a cheap hoya cpl for my cheap kitty and produced some cheap (but noticeable) results. Now i understand how cpls work :)

[luckyse7en]

Hi,
Which is the best combination of CPL and brand for sigma lens 18-200mm OS Nikon D80? and what's the price?

thanks.

rgds

[Alan_drg]

Hi,
Which is the best combination of CPL and brand for sigma lens 18-200mm OS Nikon D80? and what's the price?

thanks.

rgds

Work with any CPL on any lens laaaaa:P