Polarising filters
- Thread starter Keefh
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- Mark
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When you need one!
I use mine for different things, enhancing blue skies with clouds, cutting through reflections in water, on rocks etc, cutting through reflections in glass when shooting cars etc.
Maximum effect is at 90 degrees to the sun (eg off your shoulders rather than in front or behind you).
I wouldn't leave one on all the time, you lose about 1.5-2 stops, which can of course be useful if you've not got any ND filters and want to slow your exposures.
I use mine for different things, enhancing blue skies with clouds, cutting through reflections in water, on rocks etc, cutting through reflections in glass when shooting cars etc.
Maximum effect is at 90 degrees to the sun (eg off your shoulders rather than in front or behind you).
I wouldn't leave one on all the time, you lose about 1.5-2 stops, which can of course be useful if you've not got any ND filters and want to slow your exposures.
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- Richard
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Use a polariser as and when you need it, though for landscapes you'll probably have it more on than off.
Polarisers darken blue sky and remove reflections (from non-metallic surfaces) such as water and grass/foliage to richen the colours but you have to get your angles right and rotate the filter for best effect.
For blue skies, optimum angle is 90 degrees to the sun. Make a gun with your forefinger and thumb at a right-angle. Point at the sun and rotate your hand around the finger, and your thumb will scribe an arc pointing to the area of the sky that will be darkest. From this you'll see that when you're facing the sun, the darkened area will be above and behind you, but when the sun is to the side or behind you it'll work. Rotate to taste.
To remove reflections, the angle is 30-40 degrees to the surface. Again, rotate for best effect, though for landscapes and richening foliage there will always be some leaves or grass fronds that just happen to fall at the right angle so you'll always get something. Be careful with water - sometimes polarisers are great for seeing through shallow water, but at other times they just make the water go very dark.
Polarisers darken blue sky and remove reflections (from non-metallic surfaces) such as water and grass/foliage to richen the colours but you have to get your angles right and rotate the filter for best effect.
For blue skies, optimum angle is 90 degrees to the sun. Make a gun with your forefinger and thumb at a right-angle. Point at the sun and rotate your hand around the finger, and your thumb will scribe an arc pointing to the area of the sky that will be darkest. From this you'll see that when you're facing the sun, the darkened area will be above and behind you, but when the sun is to the side or behind you it'll work. Rotate to taste.
To remove reflections, the angle is 30-40 degrees to the surface. Again, rotate for best effect, though for landscapes and richening foliage there will always be some leaves or grass fronds that just happen to fall at the right angle so you'll always get something. Be careful with water - sometimes polarisers are great for seeing through shallow water, but at other times they just make the water go very dark.
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- Keith
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Interesting thoughts. I'll have to take it off and compare images when the sun isn't at 90 degrees. Thanks for your replies guys. Incidentally, if you're anywhere near London there's a free travel photography exhibition:RGS (with IBG) in Kensington, London, until 17 August 2014. Admission Free.
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Sure, do the comparison to see what's what, but in practise you don't have a lot of choice. The sun is where it is, so rotate the filter and see what you get - usually the band of max polarisation is quite wide and fades gradually. The time you might notice it most is with a very wide lens when the sun is low and to one side. This can create a darker patch of blue that may or may not work visually.
Same with reflections, suck it and see, but knowing how it works will explain why sometimes you don't get much effect and at other times it can be very marked.
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You can see in the viewfinder what happens as you rotate the polariser. I tend to leave mine on the lens and take it off when I don't want it.
Another - arguably easier - way of working out at what angle it will be most effective is to look for your shadow. Max effectiveness will be at 90 degrees to your shadow.
With a wide/ultra-wide lens you do tend to get uneven polarisation in the sky. It is now possible to remove this reasonably easily - in Lightroom at least. See this post
http://wp.me/p2BFlt-9w
Another - arguably easier - way of working out at what angle it will be most effective is to look for your shadow. Max effectiveness will be at 90 degrees to your shadow.
With a wide/ultra-wide lens you do tend to get uneven polarisation in the sky. It is now possible to remove this reasonably easily - in Lightroom at least. See this post
http://wp.me/p2BFlt-9w
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I know where you're coming from, but that's not strictly true. The finger-pointing-gun/thumb method is always reliable.
For example, when the sun is high and directly overhead, the finger/thumb technique indicates that there will be a dark blue graduated band all the way round the horizon 360 degrees. And this is absolutely true nearer the equator like Greece (and it looks fantastic).
In our more northerly latitude though, the sun doesn't often get that high so when your back is to the sun the polarised zone is quite high in the sky, above the horizon. In which case, at right-angles to your shadow is a good shorthand for what will probably look best
Don't use a UV filter unless you actually need it for physical protection, eg sea spray. It serves no purpose with digital and will degrade image quality with flare in some situations. ND-grads are good for darkening skies at any time.
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Lens hood provide very good protection, and can actually improve image quality.