Help On Circular & Linear Polarizer.
- Thread starter donchua
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Linear means line, Circular obviously in circular.
LP (Linear Polariser) CP (Circular Polariser)
LP requires you to rotate the filter to a point where the light entering the lens is polarised. B'cos the polarising elements are in straight lines across the filter.
CP does not need any of this adjustment, simply plug and play.
I suggest you don't save the cost and go straight to CP as you want to spent more time taking the pics than adjusting the equipment.
LP (Linear Polariser) CP (Circular Polariser)
LP requires you to rotate the filter to a point where the light entering the lens is polarised. B'cos the polarising elements are in straight lines across the filter.
CP does not need any of this adjustment, simply plug and play.
I suggest you don't save the cost and go straight to CP as you want to spent more time taking the pics than adjusting the equipment.
You GOT to be kidding me right? Where did you get that information? Hope you are not teaching your class that.
donchua said:
Hi Donchua.....
You really want to know about Polarisers the difference between Linear and Circular go to this thread where we recently had some discussion there. Look out for the explanation that was summarised by Little Wolf. It basically covers the basics on the Linear & Circular polariser.
http://forums.clubsnap.org/showthread.php?t=112906
For now, with your current camera..you should be looking to get a circular polariser. In fact with most of the modern Auto-focus lens and cameras, you should only get a circular polariser due to the way the circular version works with AF. Linear was more for those older generation manual cameras/lens mainly. When you use linear polariser on your Auto Focus camera, your AF will face problem focusing and in most cases fail. So out came the circular polariser to solve this AF problem.
And also note, linear or circular, you cant just put it on your lens and expect it to work automatically without adjusting. If you are not aware, the filter comes as two filters built-into a one piece filter. You have to turn the outer rim while looking at your viewfinder till you get the optimum polarising effect to cut glares, deepen certain colours like sky or some objects..etc.
Read that thread to get more information about polariser.
hmmm :think: , always thought that the difference is in the way light is polarised. read somewhere that in AF cameras the way light is passed through the linear polariser would somehow cause an inaccurate meter reading whereas no such problems for a circular polariser. hence for AF cameras, one would need to use circular polarisers whereas for manual focus cameras, a linear PL would suffice.
and for both types of PL filters, you'd have to manually turn one of the rings to get the required polarisation of light :dunno:
never had much experience with PL filters as I shoot saturated slides (Velvia, EVS, etc) anyway...
and for both types of PL filters, you'd have to manually turn one of the rings to get the required polarisation of light :dunno:
never had much experience with PL filters as I shoot saturated slides (Velvia, EVS, etc) anyway...
rain_danz said:
I use to shoot Velvia too and I tell you, combine that with a polariser and you will see alot more colour on ojects too as it cuts glares and reflection from the surface to let "through" the colour
Another is cutting reflection from water like the swimpool to get a clear view of what's underwater. It makes all the more difference when you use that with Velvia.
Okay..just added this bit in ......
Here is one of the reasons why a polariser is handy...at least for me. As you can see, linear or circular, you have to rotate it around to fine the optimum setting to get the best colour or in the case of my example, I use it to cut glare or reflection from my notebook. LCD has a percular way of displaying images and text on your LCD screen. When you move your head too far to the left or right, the details on the screen gets dimmeed, hidden or blurry depending on how old is your notebook model. That is because of the way light is produce and "retained" on the LCD crystal matrix...well something to that effect lah. Suffice to say, here with my circular polariser, I could even "tune-out" the screen by rotating the filter. With your fingers you rotate the whole filter but when mounted on your lens, you can rotate the outer rim to produce the same effect. Hope that clears things up abit more. It is the same for both linear and circular in that you HAVE to rotate it to get the effect.
I bought a vitacon circular polarizer.. but i figured out I can't achieve the effect of total darkness as u did with your notebook ? is there any quality differences ?
gneseew said:
Which way are you holding it? Circular polarisers are not symmetric, i.e. they have a "towards the scene" and a "towards the camera" side. If you flip the filter around, it acts differently.
gneseew said:
Hi...
Well difference in quality of polarisers is of course in proportion to the brand and price you pay. The difference will be the quality of the pictures, the residual tint if the glass is not as purely made, poor coating, poor production..etc.
But generally I have use polarisers since 1982 and that means having used even those cheap brands right up to Nikon and B+W. The one I used to creat that example with my notebook is a B+W polariser 62mm. Even my cheap ones I used long ago worked pretty well and the colours were not too bad too.
Why yours did not work no your notebook, I am not sure. As I wrote previously, you can also use that filter to cancel out or reduce glares on surfaces. I have send in some example recently in another thread talking about polarisers. Have you tried it on those example I have given?
I guess you have hold it with your fingers and did the test like I did it. Can I ask, did you notice that the filter is made up of two parts that can be rotated independent of each other? If you can't or it does not have that feature, you may have been sold a Neutral Density filter instead. But if it does have the ability to rotate but it still does not seem to give you any effect of reducing glares or deepens colour or shades, I would suggest you take that filter back to the shop and ask them why the filter is not working.
Also, did you meant no effect at all or there was some but not entirely effective like my example showed you? As I say, quality is dependent on how much you pay and also the quality of the filter production. And there is also the fact that maybe your notebook screen's lcd might be alittle difference from mine. Mine is a 4yr old compaq. heh. Yours might be those newers one with better technology.
I have not thought about what happen when you hold the filter in reverse to see if maybe that will cause the polariser to not work. But I will when I get to the office tomorrow lah. hehe my stuff are in my office so I can't do it now to check heheh.. I have never thought about it in that way leh..never have it occur to me to hold it backward and look through it heheheh.
COOL!! I've always wonder abt the effectiveness of my CPL (Raydawn, 52mm) eversince I bought it last yr... Din know there's such an easy way to check... Thanks alot sammy888!
By the way, I did a little expt to my CPL with my notebook (IBM T42) too... Turns fr clear to dark, exactly like sammy888's. However, when I reverse lens, the darker shade turns into a yellowish tint, while the clear part becomes bluish (ie. it turns fr bluish to yellowish)... Quite fun to play with... haha.
By the way, I did a little expt to my CPL with my notebook (IBM T42) too... Turns fr clear to dark, exactly like sammy888's. However, when I reverse lens, the darker shade turns into a yellowish tint, while the clear part becomes bluish (ie. it turns fr bluish to yellowish)... Quite fun to play with... haha.
Okay....update on to my last message..
I held up my Polariser and reverse it..and rotated it...and all I can see from it when looking at my LCD monitor again was that it changed the tint from colder looking colours to a warmer tint heheheh...
As I mentioned..in all my life it has never occur to me to hold it the other way around to see that it DOES NOT WORK! LOL :bsmilie:
I held up my Polariser and reverse it..and rotated it...and all I can see from it when looking at my LCD monitor again was that it changed the tint from colder looking colours to a warmer tint heheheh...
As I mentioned..in all my life it has never occur to me to hold it the other way around to see that it DOES NOT WORK! LOL :bsmilie:
limkopi said:COOL!! I've always wonder abt the effectiveness of my CPL (Raydawn, 52mm) eversince I bought it last yr... Din know there's such an easy way to check... Thanks alot sammy888!
By the way, I did a little expt to my CPL with my notebook (IBM T42) too... Turns fr clear to dark, exactly like sammy888's. However, when I reverse lens, the darker shade turns into a yellowish tint, while the clear part becomes bluish (ie. it turns fr bluish to yellowish)... Quite fun to play with... haha.
No problem man....
There are alot of stuff you can do with the polariser even indoor. I use that quite abit when I have reflective surface problems when I do product shoot. It makes it easier sometime instead of moving my flash or bounce reflectors all over the places. heh.
It just to me tryiong to get a simple explanation with being too technical. The real technical info will take more than 10 pages to explain the travelling on light particles through various mediums creating various effects. This is not a light spectrometry or scientific forum though photography does involve the use of this science to help us take better pictures.
I recommend that you go the library to read up on these. The reason mose photo retailers recommend CP is becos most lenses have a rotating front element when focusing thus misaligning the polarising effect. Also the light plays an important role as the direction, diffussion, etc affects the effect.
We can go on till the cows come home on the technical aspect, my advise go to a photo retailer with your cam and try it out.
I recommend that you go the library to read up on these. The reason mose photo retailers recommend CP is becos most lenses have a rotating front element when focusing thus misaligning the polarising effect. Also the light plays an important role as the direction, diffussion, etc affects the effect.
We can go on till the cows come home on the technical aspect, my advise go to a photo retailer with your cam and try it out.
tommon said:
But your explanations are totally wrong! And the reason why you need to use a CP on a SLR lens has absolutely nothing to do with a rotating front element, its got to do with the fact that a linear polariser will mess up your metering and/or autofocus.
dkw said:
dkw is spot on.
Taken from Canon EOS Beginner's FAQ...
Linear polarizers work well with manual focus cameras, but they interfere with autofocus cameras. Circular polarizers contain another element - a quarter wave plate - which ensures compatibility of the filter with autofocus systems. So if youve got an autofocus camera like any EOS model be sure to use only circular polarizing filters.
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