polarizing filter

Discussion in 'Graphics Programs and Photo Gallery' started by ksmattfish, Jan 15, 2004.

  1. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    I was digging through old pics, and I found this example of using a polarizing filter. Nothing special about the subject or composition, but I think it is a good example of the effects of a pol filter.

    I don't remember the kind of film. These were shot on a tripod with a Norita 6x6 w/80mm f/2 lens.

    Without polarizing filter

    [​IMG]

    Same scene at the same time with a polarizing filter

    [​IMG]
     
  2. pucci

    pucci TPF Noob!

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    whoa sweet. i gotta get me a polarizing filter.
     
  3. Bauhaus

    Bauhaus TPF Noob!

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    wow.. I'm gonna get one also.
     
  4. cich

    cich TPF Noob!

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    They also can cut through glass/water reflections (circular polarizer at least...).

    --cich

    -------------------------------------
    http://l0rdn1k0n.deviantart.com
     
  5. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    Circular polarizers and linear polarizers pretty much do the same thing. Circular polarizers were developed because linear polarizers mess with auto-focus. So if your cam is AF, make sure you get a circ pol.
     
  6. Harpper

    Harpper TPF Noob!

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    That's a huge difference! Thanks ksmattfish for posting the pictures. The lesson really hits home when we get to see the difference...

    So using a polar filter is the best way to take pictures off water shimmering in the sunlight? The problem is I currently have a P&S camera but I guess I can hold the filter lens very close to the camera lens. I want to keep the shimmer affect but it doesn't come out to well. Although it might because I had the sun over head and in front of the camera.
     
  7. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    You may find that you'll need a third hand. A polarizing filter consists of two layers of glass that must be rotated properly, based on your relative position to the arc of the sun. One hand to hold the camera, one hand to hold the filter, and one hand to turn the outer ring of the pol filter. You could use a tripod to hold the camera.

    The problem with using filters with point-n-shoots is that often they do not have TTL (through the lens) metering. The meter is actually one of those other little openings, usually above the lens. A pol filter blocks about 2 stops of light, so to get accurate metering you would need to make sure it was covering the meter, as well as the lens.

    Sounds tricky to me. Go out and buy a cheap used SLR.
     
  8. soulfly

    soulfly TPF Noob!

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    I have a nice Quantaray circular polarizer, I got it for christmas and was wondering about the rotation part, how to use it properly...etc. I never used one before and it only has a couple of sentences on the back of the box, no instructions really. In case I have said it enough times already, its a canon T70, I do landscapes thru my Sakar 75-300mm macro/zoom, this is the lens the polarizer fits. any tips would be really appreciated.
     
  9. photobug

    photobug TPF Noob!

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    soulfly- basically you want to rotate the filter until the reflection is reduced.

    For reflections , you start with the sweet part of the filter pointing in the general direction of the sun or light source, then adjust from there.

    For landscape type shots with lots of sky and the sun directly above you (or behind you), you'd start with the sweet spot pointing straight up and adjust (if needed) from there. For side or front lit scenes point the sweet spot at the light source and adjust as needed.

    "Sweet spot" you ask? Most polarizers have text along the outside of the rim. That's usually where the filter effect is most prominent. Using the text to point toward the light source should provide the maximum effect of polarization (give or take a bit).

    That's pretty much it. You have to play with your filter to determine exactly where the sweet spot for different situations is (they may be different). A small bit of colored tape on teh filter rim may be easier to use than the text, but that's personal preference.

    Have fun!
     
  10. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    Some filters have a mark at the "sweet spot". The opposite side of the ring is also a "sweet spot". On any sunny day the polarizing effect will be quite visible through your viewfinder; it will come and go as you rotate the outer ring of the filter. On overcast days it can be tougher to see it, but it's there.

    The polarizing effect is strongest when the lens axis is perpendicular to the arc of travel of the sun, and the sweet spot is rotated until it points at the current location of the sun.

    If the place on the horizon where the sun rises is 6:00, and the place where the sun sets is 12:00, then the strongest polarizing effect will occur when you are facing 9:00 and 3:00. In this position it's also very easy to line up the sweet spot with the sun.

    As your angle to the arc of the sun changes, you are turning away from 3:00 and 9:00 towards 6:00 and 12:00, the effect lessens. You may notice a change in sky tone from one side of the image to the other (darker on the side closest to the sun's arc of travel).

    Facing 6:00 or 12:00 there may be hardly any polarizing effect at all.

    Once you have the sweet spot lined up with the sun vertical movements (pointing the camera up or down, but still facing the same direction) don't seem to have much effect, but any horizontal turning will require the filter to be adjusted and the sweet spot re-aligned.
     
  11. photobug

    photobug TPF Noob!

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    Thanks Matt, for unconfusing my gibberish. :D
     
  12. soulfly

    soulfly TPF Noob!

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    thanks very much. This site has officially taught me more than all the others i've been on put together.. again. thanks.
     

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