How to use Polarising filter

[wyx087]

this always puzzles me, how come polarizers sometime appear yellow? is it just a image temperature shift and can be corrected by adjusting white balance?

when people say maximum polarization, is it when it appears yellow or slightly blue? to me all setting at any degree seems to cut away the glare on plants. glare on cars seems to be removed when it appears slight blue.



asking because i see online talks on how polarizers will make the sky bluer, yet during the blue setting, the shots with or without appear to be very similar. sky doesn't appear more blue at all.

this is the kind of difference i am seeing, the 2 comparison shots just above "DISADVANTAGES".
http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm
but i want to achieve shots similar to the road example above it, or the blue sky seen in "Polarizer at Max" image under "COLOR SATURATION" section.


thanks in advance.

 

[j07cmt]

I'll have my PL with me on Sunday.

I'm no pro, so can't answer your questions. I used them for photographing fish for my Dad's business. I use them to cut out the glare from the water - it was a case of either there is a reflection no reflection.

 

[Ploddles]

Maximum polarisation is when the lens cuts out the most light. Look through the viewfinder and rotate the filter until you get the effect that you want.

It all depends on the nature of the light at that particular time, as it is always changing. What works one day can be completely different the next day, all depending on angles etc.

 

[j07cmt]

This photo was taken using flash, and a CIR-PL to cut down glare,

 

[wyx087]

the ability to look into water is easy to determine, just rotate it until water is see through. but what about the sky?

for the sky, the two test shots i did with and without polarizer is pretty much the same, it was when i rotated it to "slightly blue" setting. i forgot to take note on the angle in relationship to the sun though.



what i find strange is that articles mention only around 10 degrees of rotation to compensate for change in angle to the sun. yet at 90 deg difference you get a yellowish image. have i got it all wrong? the yellowish view will actually give best sky if white balance is adjusted?

also tips on what to look for? desired effect is during landscape shots for bluer sky.

 

[HoppyUK]

the ability to look into water is easy to determine, just rotate it until water is see through. but what about the sky?

for the sky, the two test shots i did with and without polarizer is pretty much the same, it was when i rotated it to "slightly blue" setting. i forgot to take note on the angle in relationship to the sun though.



what i find strange is that articles mention only around 10 degrees of rotation to compensate for change in angle to the sun. yet at 90 deg difference you get a yellowish image. have i got it all wrong? the yellowish view will actually give best sky if white balance is adjusted?

also tips on what to look for? desired effect is during landscape shots for bluer sky.

Maybe you have Most polarisers are very neutral. I don't understand your yellow/blue cast references. What filter do you have?

Polarisers are all about angles - remember 90 degrees to the sun for blue skies, and for reducing reflections, between 30-40 degrees to the surface.

90 degrees to the sun: form a 'gun' with your forefinger and thumb at right angles. Point at the sun, and rotate your hand around your finger. Your thumb will scribe an arc in the sky where the maximum zone of polarisation is. When shooting into the light, this zone will be mostly behind you so that doesn't work so well. Rotate the filter for maximum effect.

If you get the angles right for reflections, they will vanish almost completely. Try this with a dark shiny car, standing towards the front, and 30-40 degress to the side. Rotate the filter (just look through it, you don't need a camera) and watch how the reflections come and go along the sides, and then on the bonnet and windscreen/roof. You can't get rid of reflections on both the bonnet and sides simultaneously (that's the 90 degrees thing at work).

Edit: with the car, when you've rotated the filter for maximum reduction of reflections, walk fowards and backwards along the side of the car. The zone of maximum polarisation will move with you, at 34 degrees to the surface (Brewster's Angle).

 

[wyx087]

ok, re-evaluated tested in a cloudy day (unfortunately). the yellow-blue cast is due to having reflection and not having reflection. when having it, it looked more yellow through the view finder, but all shots have same temperature and look similar on the same on the LCD screen.

the filter is B+W CPL MRC f-pro.

i think i understand now, unless camera is 90 degrees to the sun, you really won't be able to get that deep blue sky using a polarizer. polarizer is only really useful at reducing surface glare, but that also depends on the angle of the surface.


final question, on a sunny day where loosing 1 stop exposure isn't important, is there any negative effect with having a polarizer on all the time?