Experience with Variable NDs (Cross Polarizers)?

[ricm]

I need a high-powered 82mm ND (8-10 stops). Unfortunately the largest Hoya ND400 is 77mm. There's an 82mm variable ND from Hong Kong on the auction site that utilizes cross polarization. Has anyone purchased/used one? Singh-Ray offers one but it's waaay more than what I want to pay.

I'm wondering what the airspace is between the two pieces of glass. I could stack regular NDs (added airspace and non-plane parallel) or use gels but the convenience of a single unit is attractive.

Perhaps I need to make my own from a wratten gel.

-rm

[Bob Salomon]

Then you are in luck. Heliopan makes ND filters up to a density of 3.0 (9 stops) in all sizes through 95mm.

[ricm]

Then you are in luck. Heliopan makes ND filters up to a density of 3.0 (9 stops) in all sizes through 95mm.

Bob,

I've scoured the various retail venues and have been unable to find any Heliopans higher than .9 (8X). Where can I obtain a price quote for an 82mm/2.7 - 9 stops?

Thanks.

[cowanw]

I think that 2 polarizers stacked will give infinitely variable ND. I have used tham on my slr.The difficulty is metering for large format.
Regards
Bill

[Bob Salomon]

Bob,

I've scoured the various retail venues and have been unable to find any Heliopans higher than .9 (8X). Where can I obtain a price quote for an 82mm/2.7 - 9 stops?

Thanks.

By calling us on Monday. It is a special order item and most dealers will not have it in their price list. Rod at PhotoMark probably does have that price list.

[Bob Salomon]

I think that 2 polarizers stacked will give infinitely variable ND. I have used tham on my slr.The difficulty is metering for large format.
Regards
Bill

And the possible color casts when crossing polarizers if you are shooting color.

[Nathan Potter]

The crossed polarizers are OK in a pinch but as Bob says there will be shifts in color (I see not quite a shift as much as I see shifts in color saturation). This due to the removal of light that has been selectively polarized by various surfaces that are at critical angles in the scene. The effect as seen on the film can be a bit like the crappy color correction I have done in learning to use Photoshop.

Nate Potter, Austin TX.

[thacker8394]

Singh-Ray offers one but it's waaay more than what I want to pay.


-rm

I used to think the same way untill i broke down and purchased a singh-ray. it has proven to be invaluable for a lot of the digital shots that i do. Just my 2cents. Charles

[vinny]

By calling us on Monday. It is a special order item and most dealers will not have it in their price list. Rod at PhotoMark probably does have that price list.

Rm- make sure you're sitting down when they give you that quote. I tried to find an 82mm 6 stop nd last year. Even getting a price was like pulling teeth and it ended up being over $200 more than the 77mm size since it was a custom order.

[Jim Michael]

Might a welding helmet filter work for your application?

[ricm]

No dealer (inc. Photomark) has the special order Heliopan ND prices and I'm too scared to call HP.

As it's a low use filter I'll make one from a 4" 2.4 wratten gel.

Thanks everyone.

Rick Murai