Variable ND filters

[stigmundfreud]

Anyone know where I can get a variable ND filter from in time for the weekend preferably?!

[MartinP]

I hadn't realised you could get such things!

I guess these work by having 2 polarising filters and rotating one relative to the other to vary the light reduction. So, if you need something in a hurry you could just use a linear polariser stacked in front of a circular polariser?

[_dobbo_]

I think it would work with two circular polarisers...

[fastfreddy]

_dobbo_ said:

I think it would work with two circular polarisers...

You would need two linear polarizers...

[MartinP]

I think one circular and one linear is the way to go (just make sure the linear polariser is on the front) unless you are focusing and metering manually, in which case 2 linear polarisers would be fine.

[Simpo Two]

As I understand it AF systems don't like linear polarisers, so you could end up focusing manually.

[stigmundfreud]

Simpo Two said:

As I understand it AF systems don't like linear polarisers, so you could end up focusing manually.

thats not an issue, I only was after a variable to save carrying a box of tricks with me. Got a day time shoot tomorrow so will try and find my trusty old nd8, just hope its not a bloody grad filter

[craigbunyan]

This might clear things up a little: http://www.dmcphoto.com/Articles/VariableND/index....
SO if you have a Circ P then grab yourself a Linear and away you go...

Craig.

www.crispyimage.com

[_dobbo_]

It can be done with two CPLs, you just need to reverse one of them.



http://www.digitalphoton.net/making-a-variable-nd-...

[stigmundfreud]

cheers! I might just try the ND8 + CPL to see if it works, looking to shoot in bright light at 1/200th + flash on model

I'll have a play today in prep for tomorrow