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  #11  
Old 11th October 2012, 07:06 PM
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Martin Aislabie Martin Aislabie is offline
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The OM2n had a TTL filtering system that was weighted (all those fancy dots on the shutter screen - upside down of course).

It expected to see a bright sky and the polariser upset the exposure because the brighter sky wasn't as bright as it expected it to be.

Martin
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  #12  
Old 11th October 2012, 08:12 PM
Mike O'Pray Mike O'Pray is offline
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It is good that I have started a full discussion but I am still hoping that somebody or bodies has/have both kinds of polariser and can try both out to see if there is any greater effect to the naked eye and on the neg with the linear.

Mike
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  #13  
Old 15th October 2012, 08:02 PM
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Martin Aislabie Martin Aislabie is offline
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Mike, I'm not sure what you want from a Polariser - its a very personal thing

Personally, I have found that it is possible to over-kill reflections.

I like water to look like water and have found that while it is possible to almost remove all the reflections, the effect looks strangely false and "dead"

I like to take off some of the reflection and give hint of what lies beneath but not go too far and take off almost all the surface reflection.

In terms of effect, I am unable to tell the difference in terms of suppression of reflections, whether its a linear or a circular polariser.

I don't use any auto focus, TTL metering or anything else like that - so those potential advantages are lost on me.

Martin
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  #14  
Old 15th October 2012, 09:32 PM
Mike O'Pray Mike O'Pray is offline
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Martin, my quest is for nothing complex like the Holy Grail and it is not a "life's quest". It is simply to get to the bottom of whether there is a difference. From what you have said above, from the valuable article mentioned and from the fact that only one user on another site has claimed a difference I think I can safely conclude that there is no difference and that the difference exists in the mind of that one user.

I recently obtained "The 1981 version of Ansel Adams' "The Negative" and have read a short section on polarisers. Certainly AA makes no mention of a difference but in 1981 there were few AF cameras and AA may have had no knowledge of circular polarisers. However other later authors do mention both and once again no mention of a difference.

What AA does confirm is that the filter factor is a constant and does not, contrary to what may be a popular belief, vary with the effect of the filter on the sky.

So I feel I can safely conclude that there is no difference and my curiosity has been satisfied

Thanks all for contributions

Mike
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  #15  
Old 16th October 2012, 06:56 AM
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Mike, Schneider-Kreuznach, the maker of B+W filter, themselves claim that the filter factor of their circular polarisers varies between 2.3 and 2.8 according to how the filter is positioned in relation to the sun.

Last edited by Miha; 16th October 2012 at 07:01 AM.
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  #16  
Old 17th October 2012, 12:19 AM
JulioF JulioF is offline
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Natural light from parts of the sky, and from reflections, comes linearly polarized. So, if you really look for the angle with the filter, you should get more drastic effects with a linear. You can set it up in such a way as to get almost zero reflections, or quite low luminance (high saturation) from parts of the sky.

I have used both circular and linears and that is my experience as well.

There is another problem with metering from non-metallic surfaces - linears might kill your metering. This is why circulars are recommended for that case.

In any case polarizers are something you must try for each situation. It is silly to say that linears are better than circulars or otherwise.
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  #17  
Old 17th October 2012, 07:03 AM
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Quote:
Originally Posted by Miha View Post
Mike, Schneider-Kreuznach, the maker of B+W filter, themselves claim that the filter factor of their circular polarisers varies between 2.3 and 2.8 according to how the filter is positioned in relation to the sun.
I think this issue is complicated by the fact that part of the reason we use polarisers is to alter a scene, so the notion ofma filter factor is a bit misleading. For instance if you were shooting a blue sky at 90degrees to the sun using a polariser you'd want the filter factor to account for the added density of the filter, but not to account for the fact it would make the blue sky look a lot darker. But if for some reasn you wanted the blue sky in this example to be rendered the same tone as without the polariser you might have to increase the effctive filter factor.

To cut a long story short, when I have to compensate manually for a polariser and adjust the exposure tend to add on 1.5 or 1.7 stops depending on which is most convenient at the time. Seems to work for me.
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  #18  
Old 17th October 2012, 05:43 PM
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suggest you all have a good read of the following

http://www.bobatkins.com/photography...olarizers.html

and possibly this old thread

http://www.film-and-darkroom-user.or...ead.php?t=5852
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