Polorising filter's

SpikeK6

SpikeK6

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Spike
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Hi

I read a thread the other day about a member going to the USA and what to take, alot was mentioned about Polorising filters so I started to look around.

I always try to buy the best, but sometimes money limits me on that one, so was looking on ebay and Hoya ones are quite reasonable in price second hand BUT are there different grades of darkness to a polorising filter???

Looking at a couple of pics some seem darker than others, so IF I managed to buy a darker one would that make a beiiger diffference or should i be looking at a lighter one IF they come in different strengths???
Or are they all the same and the pics just make them darker??

Thanks

Dpike
 
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They don't come in different strengths and TBH there is nothing to choose between them on polarising ability. The difference you're seeing is in the amount of polarised light there is around to work with. With a very clear blue sky, a polariser will turn that almost black - literally - but on a hazy day the result is much reduced. And on an overcast day, they do nothing - not to the sky anyway.

Cheaper polarisers will reduce sharpness if you use them on longer lenses, but probably more relevant thing is flare, when a coated filter, or preferably multi-coated, is much better.

I use Hoya HD, because it reduces the overall exposure by about 2/3rds of a stop less than most others, and Hoya Pro-1 is also very good. As good as the very expensive German jobbies.
 
Polarisers darken blue skies as Richard said, emphasising the contrast with any white clouds, which is probably their main use (we used to use yellow and orange filters to do this with B & W film). They also make grass/vegetation and trees look greener, can make other colours seem richer, and cut out reflections from glass and water.

They are most effective when used at an angle to the sun, and the amount of polarisation depends on how much you rotate the filter.

Hoya Pro are good - I've never used any of the German B & W ones to compare them with - and it's probably worth getting one, but be careful not to overdo it. The results can start looking a bit artificial IMHO.
 
SpikeK6 said:
Thanks Martyn

Rotating the filter????

What do you mean by this

spike
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Polarising filters have a fixed part that attaches to the lens filter mount and a combined moving front part. Rotating the front moving part alters the polarising angle in relation to the direction of light, giving a greater or lesser effect. Useful for either removing reflections from non-metallic surfaces (water, glass etc) or leaving some reflection there but reducing it to taste: totally variable, it rotates freely.
As already mentioned, the full effect is when it's at 90 degrees to the light.
Stick it on the lens, turn it slowly while looking through the veiwfinder, you'll see :)
 
Thanks guys for all the answers.

I will have to wait till I get one to have a fiddle


Thanks again

spike
 
Have fun Spike, and let us know how you get on.

One thing I should have mentioned. Don't try to clean a CPL by running it under the tap or immersing it in water. You'll probably get water in between the glass elements, and then it's going to be knackered.
 
MartynK said:
Have fun Spike, and let us know how you get on.

One thing I should have mentioned. Don't try to clean a CPL by running it under the tap or immersing it in water. You'll probably get water in between the glass elements, and then it's going to be knackered.
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Is that speaking from experience :eek:
 
MartynK said:
They are most effective when used at an angle to the sun, and the amount of polarisation depends on how much you rotate the filter.

.
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The angle is 90 degrees. Shoot with the sun at your back or ahead of you and a polariser will make little difference.

Once you get the hang of it, a polariser is a great addition to your kit, especially for landscapes. Indispensible.
 
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well i never!

i just thought the CPL's were purely to do as mentioned earlier with regard to water reflections and bright skies / greenery... i knew they rotated freely in two parts but i never knew that had any effect on the images.

you learn something new every day on here don't you :thumbs:
 
If you need a stronger polarising effect, go for a linear rather than circular polariser, but you may get metering and/or AF problems.
 
Oggy said:
If you need a stronger polarising effect, go for a linear rather than circular polariser, but you may get metering and/or AF problems.
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Why? A circular polariser is just a linear polariser with a quarter wave 'circularising' plate behind it. And you will get problems.
 
HoppyUK said:
Why? A circular polariser is just a linear polariser with a quarter wave 'circularising' plate behind it. And you will get problems.
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That is not my understanding. I had been told that CPLs were actually polarised in quadrants.

Notwithstanding that I can say that my LPLs are more effective than my CPLs, and the problems if they occur are for the most part easily sorted out in PP.
 
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Oggy said:
That is not my understanding. I had been told that CPLs were actually polarised in quadrants.

Notwithstanding that I can say that my LPLs are more effective than my CPLs, and the problems if they occur are for the most part easily sorted out in PP.
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There may be a difference in the quality of the polarising foils, which are always linear as they must be, but the quarter wave plate makes no difference to that.
 
ANY thing in the optical path WILL make a difference. I am sorry that I cannot give a theoretical explanation - the last time I studied optics was at school so I am a bit rusty. Ever since then I have worked in aircraft related physics so I have not done a lot of optics.

I use polarisers quite a bit and first hand experience is what I based my answer on.

If the sun ever comes out again, I'll take some pictures to prove my point.
 
Well my first filter came today, but no blue skys at all so cannot try it, Got it off ebay, it is a Luxon make?? well it was very cheap as it was 2nd hand.
Hopefully some blue sky over the weekend so i can go try it out. ill keep you posted.

Thanks again for all the answers.

spike
 
SpikeK6 said:
Well my first filter came today, but no blue skys at all so cannot try it, Got it off ebay, it is a Luxon make?? well it was very cheap as it was 2nd hand.
Hopefully some blue sky over the weekend so i can go try it out. ill keep you posted.

Thanks again for all the answers.

spike
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The polariser's other trick is reflections.

Choose a dark car, preferably shiny, and stand three-quarters to the front. You con't need a camera for this. Look through the filter and watch the reflections on the roof, windscreen and bonnet. Rotate the filter until they disappear. Now rotate exactly 90 degrees and the reflectons on the top will reappear, and those along the doors will go.

Holding the filter in that position, walk towards the car and watch how the reflection moves along the body. You'll find that the angle of maximum polarisation is 37 degrees to the surface.

Or just hold the filter in front of your computer screen and rotate it. The screen will go black.
 
Sorry Richard - grim grey and overcast all day here so I had camera, lens and filters ready, but to no avail. :(

Spike - I would steer clear of cheap polarisers. The minimum I would expect to pay for a 49mm is about £35 (Hoya).

I do have a 52mm which came with a 52mm UV for £10 from Argos I think. It was bought as an emergency measure but when I tried the CPL on my 55-300, at 300mm I could only focus between about 2 and 20m and the picture was no ways sharp. You could end up dismissing a very useful filter because you had a poor example.
 
Oggy said:
Sorry Richard - grim grey and overcast all day here so I had camera, lens and filters ready, but to no avail. :(

Spike - I would steer clear of cheap polarisers. The minimum I would expect to pay for a 49mm is about £35 (Hoya).

I do have a 52mm which came with a 52mm UV for £10 from Argos I think. It was bought as an emergency measure but when I tried the CPL on my 55-300, at 300mm I could only focus between about 2 and 20m and the picture was no ways sharp. You could end up dismissing a very useful filter because you had a poor example.
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Long lenses and cheap polarisers don't mix. The lens only looks through a small portion of the filter and the effect of a low quality polarising foil are greatly magnified.

Not nearly so bad on wide-angles but never a great idea.
 
I know what your saying guys about cheap filters.

I have been looking at Hoya ones but what with the run up to xmas i bought this one for very little money to have a play and get practicing. I know the results will not be the same but it will give me an idea as to how they work and what to expect.
I WILL be buying a much better quality one before my hols, just need to save a little cash first.

Had a play with it off the camera and wow looking at it it looks the same colour all over. Looking forward to some blue sky's and a little sun to get out there with the camera.

spike
 
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