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Thread: polariser making images blurry.

  1. #21
    Member ykgen's Avatar
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    well, did you guys notice that at the last few pages of D70 manual says that the camera could not support PL but only C-PL fillter? correct me if i was wrong...

    i got a rather cheap C-PL filter that never satisfied me n now i've decided not to use it

  2. #22
    Senior Member sammy888's Avatar
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    Quote Originally Posted by ykgen
    well, did you guys notice that at the last few pages of D70 manual says that the camera could not support PL but only C-PL fillter? correct me if i was wrong...

    i got a rather cheap C-PL filter that never satisfied me n now i've decided not to use it
    Yes that is pretty much true what's stated in the D70 Manual WHEN you are talking about Auto Focus lens. It is not about D70 having problem with it. C-PL are made specially to be used with AF lens. The first ever made type of polarisers are thos called "PL" which works fine with manual focus lens since you are the one that is doing all the focusing.

    But with most AF lens, there are special devices built-into the lens that combine together to determine the focusing. Problem is with the older PL filters, they screw up that focusing mechanism trying to gather visual cues through the PL filter. Some more worst then others. So they came up with a Circular Polariser that is not effected by the modern day AF lens.

    Never satisfy you? Are you familiar with how a polariser works?
    Last edited by sammy888; 28th January 2005 at 10:40 PM.

  3. #23
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    Quote Originally Posted by theITguy
    Well, I have 4 Hoya filters, one of them SHMC if not wrong (sold due to strong yellow cast). I did often get finger prints on the filters due to newbie usage of my equipment the last time. Clean them with Lenspen, colour reflection of the coating changed colour. Over time in my dry cabinet it fogged up, needs constant cleaning. That happens to a Tokina CP. The B+W so far no such problem, and durable even after I dropped it on the floor while checking my equipment.
    I am still a newbie, i get finger marks and dust on my SHMC all the time. Used to clean it till it's sparkling clean but can't be bothered now.

    Well.. no yellow cast or fogging for me.. Guess I am another lucky HOYA buyer. B + W lens are super fantastic of course I must agree. Unfortunately it comes with a price I'm not willing to live with. Since I can't see any difference between the HOYA and B+W in my pictures, the choice is obvious.

    Many salesman will convince shoppers to buy B+W vs HOYA like that:

    They take out a WHITE paper and put both filters on it. B+W looks clear and HOYA has a yellow tint to it. THen he'll move it over some words and in the HOYA you can see the words 'float' a bit when it moves over it. B+W stays the same.

    Well.. I don't know what kind of demonstration is that but I wasn't moved by it.

    Best method is still to put it on the lens and shoot the white paper and see if it turns yellow. Mine didn't and the B+W din't bleach the paper any whiter.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  4. #24
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    Quote Originally Posted by sammy888
    It is not about D70 having problem with it. C-PL are made specially to be used with AF lens. The first ever made type of polarisers are thos called "PL" which works fine with manual focus lens since you are the one that is doing all the focusing.

    But with most AF lens, there are special devices built-into the lens that combine together to determine the focusing. Problem is with the older PL filters, they screw up that focusing mechanism trying to gather visual cues through the PL filter.
    It's not an issue of the lens, but the camera body. Standard SLR autofocus systems employ semitransparent mirrors and beam splitters, whose optical characteristics are highly polarization dependent. The focus sensor in the camera gets thus easily confused by linearly polarised light.

    A similar problem exists with TTL exposure metering. Even before AF days, the metering system of many cameras was somewhat sensitive towards the polarisation of the light, and the manufacturers prescribed "circular" polarisation filters to be used with them.

    "Circular polarisation filters" is actually a misnomer. They are still linear polarization filters, but add an additional birefringent layer (a so-called "quarter wave plate") after the polariser proper. After the polarisation layer has done its job, this layer converts the light to circular polarisation. Circularly polarised light is, as far as the camera is concerned, the same as unpolarized light, so the metering systems are happy again.

    It would be possible (but probably not too practical) to incorporate the "quarter wave plate" into the camera body, and one could use standard linear polarisation filters again.

  5. #25
    Senior Member sammy888's Avatar
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    Quote Originally Posted by LittleWolf
    It's not an issue of the lens, but the camera body. Standard SLR autofocus systems employ semitransparent mirrors and beam splitters, whose optical characteristics are highly polarization dependent. The focus sensor in the camera gets thus easily confused by linearly polarised light.

    A similar problem exists with TTL exposure metering. Even before AF days, the metering system of many cameras was somewhat sensitive towards the polarisation of the light, and the manufacturers prescribed "circular" polarisation filters to be used with them.

    "Circular polarisation filters" is actually a misnomer. They are still linear polarization filters, but add an additional birefringent layer (a so-called "quarter wave plate") after the polariser proper. After the polarisation layer has done its job, this layer converts the light to circular polarisation. Circularly polarised light is, as far as the camera is concerned, the same as unpolarized light, so the metering systems are happy again.

    It would be possible (but probably not too practical) to incorporate the "quarter wave plate" into the camera body, and one could use standard linear polarisation filters again.

    Ah yes you are abslutely correct there...my apologise. I was centering on the lens that I forgot it would in tandem with the TTL located in the body. I was writing about that just weeks ago heh...damn...getting really old. BUt that is a good explanation that one you wrote..more detailed.

    But it is interesting to hear that pre-af days you indicate that people has some problem with conventional PL and had to use circular PL. It was pretty much a non issue for me from my Nikon FG to my F3. It was only when I swtich over to AF type camera/lens that I started to see problem like slight off fousing or the lens would be searching to focus irratically.
    Last edited by sammy888; 29th January 2005 at 10:15 AM.

  6. #26
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    Quote Originally Posted by yanyewkay
    I am still a newbie, i get finger marks and dust on my SHMC all the time. Used to clean it till it's sparkling clean but can't be bothered now.

    Well.. no yellow cast or fogging for me.. Guess I am another lucky HOYA buyer. B + W lens are super fantastic of course I must agree. Unfortunately it comes with a price I'm not willing to live with. Since I can't see any difference between the HOYA and B+W in my pictures, the choice is obvious.

    Many salesman will convince shoppers to buy B+W vs HOYA like that:

    They take out a WHITE paper and put both filters on it. B+W looks clear and HOYA has a yellow tint to it. THen he'll move it over some words and in the HOYA you can see the words 'float' a bit when it moves over it. B+W stays the same.

    Well.. I don't know what kind of demonstration is that but I wasn't moved by it.

    Best method is still to put it on the lens and shoot the white paper and see if it turns yellow. Mine didn't and the B+W din't bleach the paper any whiter.

    Hi, are you using Digital or film? Because from what I notice using G5, White Balance set to Daylight/Manual, same picture no flash the Hoya will have the yellow cast. For Digital camera it may be easy with white balance changes, but not so easy for film camera which is my main camera.

  7. #27
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    I using digital...mm... but i've set my WB to custom, not auto. My auto WB is kinda spoilt.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  8. #28
    Senior Member sammy888's Avatar
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    Okay...had some folks pm to see some example shots of what a polariser does to enhance certain shooting scenes...so here goes. Just shot this outside my office. Sunny day but unfortunately no blue sky from where I shot the scene so no blue sky shots.

    But from this simple examples you will see how useful a polariser really is in cutting reflective glares..etc and let you photograph scene and objects with more "pure" colour coming through to your lens.

    Film like Velvia might be able to enhance the colour for your shots but it does not cut glare and reflection which is where the polariser comes into play in tandem to give your shots more details and depth.





    Cloudy though abit sunny when light fall on the trees. With the PL tuned, the trees has less reflective shine to the leaves and allowing more green to come through and the flats in the distance has a warmer and better tone to the building's painting. As you can see white over cast sky does not benefit from the PL.



    With this carpark scene I shot at about my lens at 250mm, the difference in with and without PL. The roof and tress has a more natural look to it. Btw, I set my D70 to Adobe RGB and auto WB of -2. The scene looks more alive with the greenery when a PL is use to bring out the colours of the plants and also cut reflective glare from the roof.



    Here just concentrating on the cars. Properly adjusted, your PL will be able to cut through the reflection on the car's window screen and let you see through to the car's interior.It makes for a less messy distractive shot without the glares. And sometime the colour of the car can also benefit from it if the lighting condition is right.



    You may use a better film to capture the best colours or use your PS to enhance the colours of your shots but you can not remove all the reflection off the leaves,as in this case, to give your leaves on the tree a more natural and lively look. With a Polariser, you get better colour and also cut down the glares to get more details into your shots.

    Also note that if you are not going to adjust the filter when it is on your lens, best to take it out then leave it there. Not so much because you then have more light going into your lens but also because some PL when not tuned properly will add a slight colour tint to your pictures. That is why some people find this or that PL has a yellow cast or green..etc. If you want to put a PL on your lens, you have to make use of it.

    So for those who asked me for some examples...here you go .

  9. #29

    Default Re: polariser making images blurry.

    Sorry but the photo with the polarizer on looks better to me what

    Quote Originally Posted by THEMAN
    and here's another image. The blur isn't as bad but the colour. . I am so surprised - been wondering why my shots were so lousy in colour. Taking off that piece off crap starting today. Its is circular polarising one.


  10. #30

    Default Re: polariser making images blurry.

    Crap, that photo brings back memories of while I was back in Sydney.. That's the somebody royal's house or something converted to a shopping centre right? You live right next to it?

    Quote Originally Posted by THEMAN
    Last edited by jeryltan; 18th January 2006 at 01:12 PM.

  11. #31

    Default Re: polariser making images blurry.

    Quote Originally Posted by jeryltan
    Crap, that photo brings back memories of while I was back in Sydney.. That's the somebody royal's house or something converted to a shopping centre right? You live right next to it?
    It sure looks like the Queen Victoria Building (QVB) in Sydney

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