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Thread: Determining better UV filter from lights reflecting from filter surface?

  1. #1

    Default Determining better UV filter from lights reflecting from filter surface?



    Here's a comparison of 2 filters. They're UV filters, not polarizing filters, but the comparison here is between coatings so it's still relevant. On the left is a high end Hoya HD UV filter. On the right is a super cheap Targus "multi coated" filter that I bought at WalMart (UV + CPL costs all of $16 USD). Both filters are angled so they reflect the exact same light bulb, a 40 watt CFL in my home office. Both filters are sitting on a white towel.

    Now remember, the coating on a filter i supposed to help PREVENT reflections. The idea is to allow more light through the glass by reflecting less of it. So the brighter the reflection, the crappier the coating. I think the picture speaks for itself. It's worth noting that the effect is even more dramatic when I'm holding the filters away from a surface. Having the towel right behind the filters is creating sort of a "mirror" effect. But I have yet to figure out how to precisely aim both filters to simultaneously reflect the light while taking a picture of them.

    Keep in mind, even the crappy Targus filter is marketed as "multi coated". An uncoated one would be worse. All that reflected light is light that doesn't get into the camera when you need it.

    Quoted:
    http://www.pentaxforums.com/forums/p...tml#post965377

  2. #2

    Default Re: Determining better UV filter from lights reflecting from filter surface?

    Want to ask guys here who have some ideas or had thot about this qns before....
    how true is the view?

  3. #3

    Default Re: Determining better UV filter from lights reflecting from filter surface?

    My own photo of 2 diff uv filter
    color r diff frm the reflection...




  4. #4

    Default Re: Determining better UV filter from lights reflecting from filter surface?

    both photo taken using manual

    Focal length: 70mm
    F: 2.8
    Exposure: 1/25 sec

  5. #5
    Moderator Octarine's Avatar
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    Default Re: Determining better UV filter from lights reflecting from filter surface?

    Quote Originally Posted by eugene260880 View Post
    both photo taken using manual
    Focal length: 70mm
    F: 2.8
    Exposure: 1/25 sec
    That one possible reason why you see different colours, the light source is not CFL. The original test was done:
    Both filters are angled so they reflect the exact same light bulb, a 40 watt CFL in my home office.
    EOS

  6. #6
    Senior Member wildcat's Avatar
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    Default Re: Determining better UV filter from lights reflecting from filter surface?

    Quote Originally Posted by eugene260880 View Post
    My own photo of 2 diff uv filter
    color r diff frm the reflection...



    What about white balance on the camera?
    Also flourescent lighting depends on the frequency of the light.. would prefer test on a tungsten light or something that doesn't flicker at high frequency.

    Anyway I stopped using UV filters on my cameras coz I only have the cheapo ones and they cause ghosting under certain flourescent light conditions
    Last edited by wildcat; 8th July 2010 at 07:15 PM.

  7. #7

    Default Re: Determining better UV filter from lights reflecting from filter surface?

    Tmr nite then try with CFL....
    Hmmm..........

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