Comments on: Making a variable ND filter with circular polarizers http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/ Photography & Photoshop Blog Thu, 08 Apr 2010 08:58:29 +0200 http://wordpress.org/?v=2.8.4 hourly 1 By: Vincent jansen http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-3944 Vincent jansen Thu, 08 Apr 2010 08:58:29 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-3944 I've been expirimenting with pol-filters, and also with the variable ND filters from Lightcraft (LP or CP?). The light over the image is not uniform over the entire image with the LIGHT Craft filter, and when you are really blocking the light very strong the light measuring will become very inaccurate (over- and underexposed) I’ve been expirimenting with pol-filters, and also with the variable ND filters from Lightcraft (LP or CP?). The light over the image is not uniform over the entire image with the LIGHT Craft filter, and when you are really blocking the light very strong the light measuring will become very inaccurate (over- and underexposed)

]]> By: matt tarr http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-2472 matt tarr Mon, 07 Sep 2009 00:07:55 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-2472 I was at UP in 3d... with my polarized sunglasses. found that my glasses and the 3d glasses (when rotated and ordered correctly) could block a significant amount of light. Came home and using a cheapo polarized filter, a step-down ring and some scotch tape... I had a Variable ND. I don't claim to understand but I swear there is very little change in the color of the light... it isn't perfectly even across the rotation (especially at the darkest)... but man... it gets DARK... can someone explain what those 3d polarized lenses are doing? I was at UP in 3d… with my polarized sunglasses. found that my glasses and the 3d glasses (when rotated and ordered correctly) could block a significant amount of light. Came home and using a cheapo polarized filter, a step-down ring and some scotch tape… I had a Variable ND. I don’t claim to understand but I swear there is very little change in the color of the light… it isn’t perfectly even across the rotation (especially at the darkest)… but man… it gets DARK… can someone explain what those 3d polarized lenses are doing?

]]> By: Sam http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-1791 Sam Wed, 03 Jun 2009 01:32:38 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-1791 Zoom in. When shooting at wide angles, some lights are not perpendicular to the glass thus won't be blocked by either filter. Lens hood may help a bit. The cross you see represents the relative angle between the polarization directions of the two filters. If they are 60 degrees apart it's going to be a 60 degree cross. Of course if the angle is not close to 90 degrees the cross will be much less visible, most likely drowned by other lights. Zoom in. When shooting at wide angles, some lights are not perpendicular to the glass thus won’t be blocked by either filter. Lens hood may help a bit. The cross you see represents the relative angle between the polarization directions of the two filters. If they are 60 degrees apart it’s going to be a 60 degree cross. Of course if the angle is not close to 90 degrees the cross will be much less visible, most likely drowned by other lights.

]]> By: yardieLion http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-1258 yardieLion Tue, 10 Mar 2009 10:46:55 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-1258 Hey, I tried this WE, with two Hoya Pro1 CPL, and the front one inverted : variable ND works well, but I do have one blue-cross along the entire image, so this isn't usable. I'll try to put some examples. I was really disappointed when I saw this cross. Any idea of avoiding this? Hey,

I tried this WE, with two Hoya Pro1 CPL, and the front one inverted : variable ND works well, but I do have one blue-cross along the entire image, so this isn’t usable.
I’ll try to put some examples.
I was really disappointed when I saw this cross.

Any idea of avoiding this?

]]> By: Marisela http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-156 Marisela Wed, 29 Oct 2008 14:36:39 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-156 Interesting to know. Interesting to know.

]]> By: Cuki http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-155 Cuki Tue, 28 Oct 2008 15:50:02 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-155 Addenda: In fact, the effect is not well described as a dark St. Andrew's cross, since the dark area is supposed to be there. The problem is that I get non-blocked light along the edges of the frame. The resulting black cross rotates along with the camera (the unblocked light areas stick to the edges of the image), and it can't be seen with the bare eyes, therefore I guess that the effect is related not just to the cheap filter combination, but somehow to the whole filter+camera combination. I can get rid of that light (and the dark cross effect) if I zoom in. So this is only half of a dead end for my el cheapo vari-nd. Addenda: In fact, the effect is not well described as a dark St. Andrew’s cross, since the dark area is supposed to be there. The problem is that I get non-blocked light along the edges of the frame. The resulting black cross rotates along with the camera (the unblocked light areas stick to the edges of the image), and it can’t be seen with the bare eyes, therefore I guess that the effect is related not just to the cheap filter combination, but somehow to the whole filter+camera combination.

I can get rid of that light (and the dark cross effect) if I zoom in. So this is only half of a dead end for my el cheapo vari-nd.

]]> By: Cuki http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-154 Cuki Tue, 28 Oct 2008 15:39:04 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-154 I've tried this with a cheap linear (Hitech UK) in front of a cheap circular (Promax PRC). I don't have a problem with the "polarized effect", as long as it is adjustable by rotating the whole block. I do have though a big problem with the non-uniform blocking of the light (with the bare eyes I can't see it happening, but in the picture there's a quite obvious dark cross-shaped shadow in the center of the image). I wonder if it's just the poor quality of the filters to blame here. I’ve tried this with a cheap linear (Hitech UK) in front of a cheap circular (Promax PRC). I don’t have a problem with the “polarized effect”, as long as it is adjustable by rotating the whole block. I do have though a big problem with the non-uniform blocking of the light (with the bare eyes I can’t see it happening, but in the picture there’s a quite obvious dark cross-shaped shadow in the center of the image). I wonder if it’s just the poor quality of the filters to blame here.

]]> By: Daniel http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-47 Daniel Sun, 17 Aug 2008 10:27:01 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-47 <p><em>JRSFORUMS</em><br /> Good info, thanks. Although with a LP in front, you get a polarized effect to the image.<br /> If you hold the CPL backwards up infront of a polarized light source such as an lcd screen, do you still not get a cast?</p> <p><em>David</em><br /> Thanks for the info, I'll add it to the list!</p> JRSFORUMS
Good info, thanks. Although with a LP in front, you get a polarized effect to the image.
If you hold the CPL backwards up infront of a polarized light source such as an lcd screen, do you still not get a cast?

David
Thanks for the info, I’ll add it to the list!

]]> By: David http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-44 David Tue, 22 Jul 2008 00:09:46 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-44 Hoya HMC 58mm PL-CIR has mild yellow/blue cast. Hoya HMC 58mm PL-CIR has mild yellow/blue cast.

]]> By: JRSFORUMS http://www.digitalphoton.net/making-a-variable-nd-filter-with-circular-polarizers/comment-page-1/#comment-42 JRSFORUMS Thu, 10 Jul 2008 21:55:46 +0000 http://harteex.kicks-ass.net/domains/kvarfordtphotography-com/blog/?p=33#comment-42 Like cooking, to get good results you need good ingredients. I built one with a Hoya Pro1 CPL and a Hoya LP. I get no casts...at all. If I were doing it again, I would use a B+W MRC LP and a B+W F-Pro (MRC) CPL. The Hoya Digital Pro1, is not as good as the old Pro1....and the MRC LP would probably have less chance of any reflections. Total cost, depending on where you source them +/- $200 vs. + $300 for the Singh-Ray Like cooking, to get good results you need good ingredients.

I built one with a Hoya Pro1 CPL and a Hoya LP. I get no casts…at all.

If I were doing it again, I would use a B+W MRC LP and a B+W F-Pro (MRC) CPL. The Hoya Digital Pro1, is not as good as the old Pro1….and the MRC LP would probably have less chance of any reflections.

Total cost, depending on where you source them +/- $200 vs. + $300 for the Singh-Ray

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