Someone with some more optics or physics experience may be able to answer this questions.
What would be the effect of stacking a CPL filter (circular polarizer) under a linear polarizer filter: Could this serve as a poor mans Varible ND filter?
Someone with some more optics or physics experience may be able to answer this questions.
What would be the effect of stacking a CPL filter (circular polarizer) under a linear polarizer filter: Could this serve as a poor mans Varible ND filter?
Last edited by iND; 04-24-2012 at 09:32 PM.
Yes. That is how the Singh-Ray Vari-ND works.Originally Posted by iND
I've got one of those reversal adapters, 72mm male to 77mm male thread, intended for macro work revering a lens and mounting another lens on the front (which i've never actually tried, I should one day).
Instead, I tried mounting two CPLs front-to-front (so Circular Pol faces the sky and faces the sensor, Linear Pols face each other), to try emulating a Vari-ND. It didn't work too badly (I never used it too much because soon after that I got my ND400), but at the darkest settings it went a bit (a lot) purple.
So using a Linear Pol facing the sky (in either direction) and CPL facing the sensor (in the normal direction) should work just the same, but seeing as it wasn't designed as such you'd probably get some weird colours. Worth a test though...
An awful lot of electrons were terribly inconvenienced in the making of this post.
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