Has anyone used a variable ND filter?

[GlenMH]

I came across one of these on Amazon: http://www.amazon.co.uk/gp/product/B004TQL604/ref=...

Has anyone ever used one? What is the optical quality like?

[Simpo Two]

Well that's a weird one - thought it was three to stack but on closer inspection it looks like polarisers rotating against each other.

[GlenMH]

Simpo Two said:

Well that's a weird one - thought it was three to stack but on closer inspection it looks like polarisers rotating against each other.

Yes - which raises some questions about AF through it (D90 body...) and potential interference effects.

It is not that expensive so might be worth a punt.

[tinman0]

ad said:

Some vignetting may occur

No kidding! Seen the size of it?

[markmullen]

It is a pair of polarisers, some guys on Talkphotography have tried them, no-one was too impressed, lots of banding of skies on wide lenses.

[GlenMH]

Thanks for that - exactly what I was looking for. May be not worth a punt....

[Fordo]

I know a lot of video guys like using them on 5d's & 7d's - personally, i don't like them. They do the job, but you get strange polarization effects on some types of glass and reflective surfaces. Its all a bit unpredictable for my liking.

[RobDickinson]

I've used one, borrowed from a friend. Was very tempted for a long time BUT they dont work so well at a wide angle.

10-16mm(crop) your limited to about 3 stops before you get the cross effect.