Polarising and ND filters
- Thread starter nikonuser
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- Kev
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The amount of light it blocks will vary as you rotate it. It could vary between roughly 1 and 3 stops depending on the filter.
It may also affect reflections from the water and foliage depending on the rotation, this may be OK or it may not be what you want.
The best thing is to try it and see!
It may also affect reflections from the water and foliage depending on the rotation, this may be OK or it may not be what you want.
The best thing is to try it and see!
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- Kev
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Have a search of the forums for
welding glass
honest.
Here is a link to what I think was the first one
http://www.talkphotography.co.uk/forums/showthread.php?t=151141&highlight=welding+glass
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- Ron
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You can use two polarising filters as an adjustable ND filter. there is only a small rotation needed between clear and completely black but it does work.
As there are no marks on the filters you need a bit of trial and error to get the right exposure but its worth doing. you get an eye for the setting after a while and can take an educated guess at exposure times.
Failing that the welding glass method works as a cheap alternative.
As there are no marks on the filters you need a bit of trial and error to get the right exposure but its worth doing. you get an eye for the setting after a while and can take an educated guess at exposure times.
Failing that the welding glass method works as a cheap alternative.
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You can use a polarising filter as an ND, but you won't get more than two stops extra exposure of overall neutral density from it, probably a little less - most are about 1.7 stops.
In addition to that, areas of the subject that are darkened by the polarising effect will be affected more. That depends entirely on the amount of polarsied light there is (not on the filter) and is typically an extra two or three stops on top. However, it only affects certain parts of the image so is not really the effect you are looking for.
Using two polarising filters together is fine in theory but in practise there are a few problems that make it both difficult (vignetting, potential image degradation, trouble adjusting exposure) and, at the end of the day, as expensive a solution to do properly as buying a custom ND. Hence its lack of popularity. However, you do get a variable ND out of it.
In addition to that, areas of the subject that are darkened by the polarising effect will be affected more. That depends entirely on the amount of polarsied light there is (not on the filter) and is typically an extra two or three stops on top. However, it only affects certain parts of the image so is not really the effect you are looking for.
Using two polarising filters together is fine in theory but in practise there are a few problems that make it both difficult (vignetting, potential image degradation, trouble adjusting exposure) and, at the end of the day, as expensive a solution to do properly as buying a custom ND. Hence its lack of popularity. However, you do get a variable ND out of it.