Fader ND filters

[steve.82]

Can this be done with a pair of polarizers? I remember when I was a kid mucking around with a pair of polarizers from some LCD displays.

 

[steve.82]

Been investigating... looks like it will work if the first polarizer the light hits is reversed, so the light doesn't become 'unpolarized' before hitting the second polarizer

 

[woof woof]

Interesting. But what effect does it create?

 

[steve.82]

a variable nd filter as you twist them relative to each other

 

[SamHH]

I think there can be some problems with using this sort of variable ND filter with wide angle lenses. Have you read about that?

 

[steve.82]

Only vignetting and that's fairly common sense really. Just need some biiiiig polarizers and a step up ring to solve that.

 

[Canon Bob]

I think there can be some problems with using this sort of variable ND filter with wide angle lenses. Have you read about that?

Only vignetting and that's fairly common sense really. Just need some biiiiig polarizers and a step up ring to solve that.

I suspect that you'll see more than just potential vignetting. The effect of dual polarisers will also induce banding across the frame, more so as the focal length (shortens angle of incident light broadens).

Bob

 

[steve.82]

Ahh right. Hmmm, well hopefully will find out tonight