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Author Topic: all about nd filters  (Read 4645 times)

melchiorpavone

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Re: all about nd filters
« Reply #20 on: September 04, 2014, 08:37:12 am »

Hi,

While White-balancing will get us a long way towards a more neutral rendering of close to spectrally neutral colors, it doesn't guarantee that other colors are also 'correct'. The contribution of excess IR (that the built-in IR filter cannot cope with) will contaminate all colors, because the Bayer CFA filter dyes are transparent to IR.

Depending on the colors in the scene, that may result in (at best) a muddy/brownish overall cast, but it may also turn into a color cast that is very difficult to remove in post-processing (even when neutral colors are rendered as neutral).

Cheers,
Bart

This is why digital sucks. Use film!
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Ellis Vener

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Re: all about nd filters
« Reply #21 on: September 04, 2014, 12:05:36 pm »

Hi,

While White-balancing will get us a long way towards a more neutral rendering of close to spectrally neutral colors, it doesn't guarantee that other colors are also 'correct'. The contribution of excess IR (that the built-in IR filter cannot cope with) will contaminate all colors, because the Bayer CFA filter dyes are transparent to IR.

Depending on the colors in the scene, that may result in (at best) a muddy/brownish overall cast, but it may also turn into a color cast that is very difficult to remove in post-processing (even when neutral colors are rendered as neutral).

Cheers,
Bart

If processing in Adobe Camera Raw (either as part of Photoshop or in Lightroom), would creating  a custom profile for a camera and filter combination, either using the Adobe DNG editor or X-rite's ColorChecker Passport software,  resolve this issue?
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Pope

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Re: all about nd filters
« Reply #22 on: September 04, 2014, 12:49:47 pm »

How do I correct the blue casting of the Lee Big Stopper with film? Do you have any tips to use it with a Velvia 50 or Ektar 100?
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melchiorpavone

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Re: all about nd filters
« Reply #23 on: September 04, 2014, 12:52:45 pm »

How do I correct the blue casting of the Lee Big Stopper with film? Do you have any tips to use it with a Velvia 50 or Ektar 100?

Use a different filter, of course.
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Some Guy

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Re: all about nd filters
« Reply #24 on: September 04, 2014, 05:12:42 pm »

Did a little more testing and some images with the Nikon D7000 in sunlight.

Three rows shown:

One with camera at factory default Auto White Balance shot normally without a filter, one through the Lee "Big Stopper," and final through the B+W 10 stop ND filters.
Second row is showing my Auto White Balance settings in the AWB Coordinate Window in the camera menu if you want to use Auto White Balance.
Third row is by altering the Kelvin in the camera manually to match the one without (as close as I could get).

I used Capture NX 2 and tried to keep the Red & Blue as close to 1.00 as possible, or within +/- 0.02.

I have a Lee "Little Stopper" 6-stop ND too, but didn't try it against the 10-stop ND ones.

Too bad in Row 1 that B+W and Lee cannot get closer to neutral than they do.  Seems like they would have had practice by now to refine them.

SG
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Pope

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Re: all about nd filters
« Reply #25 on: September 04, 2014, 06:47:04 pm »

Use a different filter, of course.
Thank You... Which one do you recommend?
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melchiorpavone

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Re: all about nd filters
« Reply #26 on: September 04, 2014, 08:12:17 pm »

Thank You... Which one do you recommend?

Something dead neutral. I don't use them, I have no use for them.

http://www.digitalcameraworld.com/2014/05/22/best-nd-filter-6-top-models-tested-and-rated/
« Last Edit: September 04, 2014, 08:23:29 pm by melchiorpavone »
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Ellis Vener

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Re: all about nd filters
« Reply #27 on: September 05, 2014, 10:17:55 pm »

A test from today to see how various camera calibration profiles in ACR/Lr5.6 might affect color balance. Nikon D810 with AF-S 70-200 f/2.8G VR lens and B+W ND 3.0 (ten stop) filter for all photos.  Mid afternoon sunlight (clear sky). Camera set to ISO 64, 14-bit lossless NEF, Processed in Lightroom 5.6. The same frame was processed four ways and output as a 100% JPEG in sRGB. Processing notes are in each frame.
i recommend you look at it in Photoshop and not your browser.
« Last Edit: September 05, 2014, 10:22:04 pm by Ellis Vener »
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Some Guy

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Re: all about nd filters
« Reply #28 on: September 06, 2014, 10:47:37 am »

A test from today to see how various camera calibration profiles in ACR/Lr5.6 might affect color balance. Nikon D810 with AF-S 70-200 f/2.8G VR lens and B+W ND 3.0 (ten stop) filter for all photos.  Mid afternoon sunlight (clear sky). Camera set to ISO 64, 14-bit lossless NEF, Processed in Lightroom 5.6. The same frame was processed four ways and output as a 100% JPEG in sRGB. Processing notes are in each frame.
i recommend you look at it in Photoshop and not your browser.


Ellis, something looks oddly muted in your Colorchecker for some reason.  Colors seems more pastel and low contrast (Aside from the red cast off the B+W filter in first shot.).

There is that Adobe "Blue punch" too and I guess ACR is responsible for that.  I'm not fond of using Adobe's ACR as first run out of the camera as it overlooks a lot of things that the camera can add (Dynamic Range), and it seems to me that Nikon's software works better for the first NEF read and than save as a TIFF file for me (unless I want a dramatic blue sky!).  Then I can go to Adobe once Nikon has addressed the camera settings.

The following two images are the same NEF>JPG from my D7000 in daylight:

One is out of Capture NX-D (the freeware one labeled CapNX-D_A3_DSC1504C one), and the other is out of Adobe Camera Raw 8.6 (The ACR_DSC1504C one).  What I noted was that there is the "Adobe Blue punch" over Capture NX-D, but the NX-D version shows more contrast as well as the better shadow detail in the dogs back too (Auto Dynamic Range perhaps that Adobe ACR cannot do?).  The green neon lanyard strap is closer in NX-D too where ACR washes it out a bit.  The plaster dog is actually more yellowish (dirty dog) than white too.  I did leave the camera's WB tuning on A3, 0 for the Auto White Balance too as it images a bit cooler.  I don't know if Adobe addresses that WB change either, but this is the same image dumped from NEF to JPG in the two editors.

Also, look at the lettering at the bottom of the baking soda box (Net weight 454 grams).  ACR seems a bit fuzzy and blends the colors where NX-D separates them better.

I know there are 9 things ACR cannot do with Nikon's proprietary NEF files.  They've been outline in this article: http://photographylife.com/how-to-get-accurate-nikon-colors-in-lightroom

Anyway, I would've expected your D810 to do better on the colors than displayed.  Might be the first one is flare off the Colorchecker and it carried over to the others in post?


Also, someone asked about the "Lee Big Stopper" with film and corrective filter.  Maybe a 81C or 81D and using 11 stops for the exposure?  I know with the B+W the large format film shooters like a 80D (bluish).  Then the lab might be a bit closer in correcting the ND color error.


SG
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