2 stacked CPs instead of NDs?

chrisdg

Hello,

So, I was about to purchase two or three B+W Neutral Density filters, likely a 0.9 (3-stop), a 1.8 (6-stop), and a 3.0 (10-stop) when I came across this tip:

"A polarising filter offers a similar light reducing option as a Neutral Density 4x filter. Add two polarisers together and you can get an infinitely variable ND from 4x to very strong (almost black) by rotating the front one."

Since I already have a B+W CP filter...perhaps I should just get another (thin design) and stack them. Has anyone successfully used this approach?

I suppose there are several other variations I could employ as well: for example, a 1.8 ND stacked with a CP for approx 10-stop loss?? This would theoretically give the anti-glare/color-enhancing benefits of the CP, couple with reduction in light to smooth out water, etc.

SECOND RELATED QUESTION: I also have a Cokin filter holder as an option instead of screw-ins...does anyone know if the square ND filters leak in light? The only reason I consider this approach is I am not sure how long I will have my 10-22efs ultra-wide (77mm filter), since I am considering an upgrade from the 30D to full-frame sensor.

Thanks!

ziggy53

I think you'll find a decent answer in this thread:

http://www.dgrin.com/showthread.php?t=65335

Scott_Quier

chrisdg wrote:

Since I already have a B+W CP filter...perhaps I should just get another (thin design) and stack them. Has anyone successfully used this approach?

I've heard of this being done. I've also heard, in the same source, that you run the risk of strange color casts that are not consistant across the entire frame, making a CWB useless. That's just what I've read - never tried. it. You could check this out though.:D

cmason

chrisdg wrote:

SECOND RELATED QUESTION: I also have a Cokin filter holder as an option instead of screw-ins...does anyone know if the square ND filters leak in light? The only reason I consider this approach is I am not sure how long I will have my 10-22efs ultra-wide (77mm filter), since I am considering an upgrade from the 30D to full-frame sensor.

Thanks!

I have had very good luck using my Cokin filter holder with a ND 4 while also using a B+W Circ Polarizer on my lens. Stacking Cokin filters works very well as far as I can see, no light leakage and no oddball reflections. I would prefer to put the Cokin filters literally stacked on one another, but I suspect this risks scratches, and the filter holder does hold them very close together.

I have not tried this on my 10-20 Sigma, (because I dont have a 77mm holder). But I suspect the holder might get in the way. I do know that handholding a Cokin P filter to the Sigma lens works just fine.


Here is a shot with a Cokin ND 4 in holder and Circ Polarizer (lens screw-in) together.

chrisdg

Thanks guys!

So i just got the 77mm adapter for my cokin P holder...and as expected, it is quite visible in the frame between the 10mm-14mm range (approx) on my 10-22efs. Since I use this lens at the widest angle about 95% of the time, I think I'll go for the dedicated 10-stop filter from B+W.

If I upgrade my 30D to a the upcoming 5DII, i'll just hope to find a FF-compatible ultra-wide angle with the same 77mm diameter or sell the filter along with the 10-22efs and 17-55efs