[van-Pen]

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I like taking low speed shots of water etc but have limited filters to reduce shutter speed. I have looked at the variable density filters but these seem expensive.
I am in the process of moving from Cokin A to Coking P size and have a pair of polarizers. Since I have an A to P adaptor I wondered if I could use these in combination to create my own variable ND filter.
Having mounted them the affect seems to work but need to plan a field trip to test this outside.
Has anyone tried this and have you any tips on this approach?
Once I get outside I will post some results.

[lmd91343]

I've taken a Tiffen and a Hoya HMC 72mm put them together and marked off full stop values on the rims (measured with a spot meter thru the filter pair).

I am unhappy with the first round test results. The Hoya side facing the Tiffen internally is not fully clean. The light path must go thru 4 layers of glass, 2 polarizing screens, and 2 quarter wave plates. May be too much degradation.

I've noticed the ones selling for about $20 on ebay have the same markings on the rim as the much more $xxx Kenko one.

Anyway, there will be 2 less glass plates and one less quarter wave plate. So it may perform better.

I want to use it on my film camera with the lens wide open to f0.95 for DOF effects.

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Kenko 77mm Variable NDX Neutral Density Filter KNDX77 B&H Photo