Make your own super Neutral Density filter

[DPNow]

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It's currently very fashionable to use extremely dark neutral density filters so you can use very long exposures in day time for special effects like smoothing the water surface turmoil of rivers, canals, lakes, etc., or for making the clouds in the sky look like they are racing past. There are expensive and cheap filters that can help you achieve this, but we look at a different strategy altogether; using a pair of polarising filters. Find out if it works.

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[Ian]

Re: Make your own super Neutral Density filter

I have done a little more work on one of the images I produced for this article:



Apart from the disc of flare in the centre top caused by some dust inbetween the two polarisers I used, I'm quite pleased with the result.

This is a 13 second exposure. The normal exposure without the filters was 1/200th.

Ian

[Stephen]

Re: Make your own super Neutral Density filter

This is an interesting little project Ian. I'll bet you really enjoyed the process.

Its always been my feeling that true neutral density filters should not give a colour shift. I always felt that this was the case with my Lee ND grads. However you mention that the Big Stopper does apply a colour shift which really surprised me. Your polarising set up does seem to apply a colour shift and of course the method you left out was the Infra Red filter which Andrew Thatcher uses and of course this has an even more marked effect. The end result then does mean that you need to apply some more toning to get a pleasing result. The one you have shown above is a pretty good result in this respect.

[Ian]

Re: Make your own super Neutral Density filter

This is an interesting little project Ian. I'll bet you really enjoyed the process.

Its always been my feeling that true neutral density filters should not give a colour shift. I always felt that this was the case with my Lee ND grads. However you mention that the Big Stopper does apply a colour shift which really surprised me. Your polarising set up does seem to apply a colour shift and of course the method you left out was the Infra Red filter which Andrew Thatcher uses and of course this has an even more marked effect. The end result then does mean that you need to apply some more toning to get a pleasing result. The one you have shown above is a pretty good result in this respect.

Sorry for any confusion, my reference to the colour shift was the cheap option of buying a welder's filter, not the Lee Big Stop. I haven't used the Lee filter but I'm reasonably sure it gives a proper neutral result.

Ian

[Patrick]

Re: Make your own super Neutral Density filter

Sorry for any confusion, my reference to the colour shift was the cheap option of buying a welder's filter, not the Lee Big Stop. I haven't used the Lee filter but I'm reasonably sure it gives a proper neutral result.

Ian

This is a very interesting experiment. However it occurs to me two good quality polarized filters will cost more than the big stopper, true there is the advantage of varying the amount of light entering the lens.
The slight colour shift in my view is not important it is easily corrected.

Does a manufacturer make such a combination it looks as if it could be worthwhile?

Patrick

[Ian]

Re: Make your own super Neutral Density filter

This is a very interesting experiment. However it occurs to me two good quality polarized filters will cost more than the big stopper, true there is the advantage of varying the amount of light entering the lens.
The slight colour shift in my view is not important it is easily corrected.

Does a manufacturer make such a combination it looks as if it could be worthwhile?

Patrick

[Graham_of_Rainham]

[Ian]

Re: Make your own super Neutral Density filter

Good job, Graham, hope you have more fun with the idea!

Ian