Better dynamic range with ND-Fader filter?

I just stumbled over this while doing some tests. Looks like you get better DR ( in theis case more texture in the shadows, while highlights stay the same) when using a Fader-ND filter (probably any ND Filter) than stopping down the iris.So here is a quick and dirty test

I used the MTF BMC and a Samjang 24mm.
Heliopand fader ND and a Heliopan IR filter on top of it.

Picture 1:

I Stopped down the iris, till the 100% zebras on the bright spots in the background just went away.

2

Picture 2

I dialed in the fader ND, till the 100% zebras on the bright spots in the background just went away.

1

So in a real word scenario I would do exactly this, dialing it down, till my zebras just go away (maybe a even hair more, cause one channel may already clipping, without the zebras showing up). When using the aperture, my shadows are going much darker before I reach that level. Using the ND, gives me more wiggle room in my shadows.

UPDATE:
Looks like the mystery is solved, why the ND fader does that trick:

As Gerardo Campos pointed out:

The reason is very simple: is because the ND fader are made of 2 polarized filters, so when you use a polarizer you cut light from the highlights giving you more space to play in your shadows; then the 2 polarized filters from the ND Fader in first place cut the highlights and when you start to rotate it start to act in all other lights.

And here is the reason why that doesn’t work with traditional ND filters:

the normal ND push down all lights equaly, so shadows and lights go down; but Circular Polirazed filter cut only hi light, is the best filter to obtain a blu sky and a bright terrain

Frank

15 thoughts on “Better dynamic range with ND-Fader filter?

  1. Really interesting finding…..(what was the iris set at to start with on the test stopping down using only the ND fader?)
    Can’t wait to see your tests on the 4K BMC and the Pocket on too….
    Always enjoy and look forward to your work and tests

  2. Pingback: Blackmagic Cinema Camera: Better Dynamic Range with ND-Fader Filter? A Quick & D. Test, by Frank Glencairn | digital-cinema-tools.com

  3. The reason is very simple: is because the ND fader are made of 2 polarized filters, so when you use a polarizer you cut light from the hilights giving you more space to play in your shadows; then the 2 polarized filters from the ND Fader in first place cut the hilights and when you start to rotate it start to act in all other lights.

    • So a normal ND filter would have the same effect then? because it cuts the light equal in high as lows?

      • Yuke; no, because the normal ND push down all lights equaly, so shadows and lights go down; but Circular Polirazed filter cut only hi light, is the best filter to obtain a blu sky and a bright terrain

    • Looks like you solved the mystery, I gonna update my article with this new information. Thanks for sharing, Frank

      • Very interesting Info.
        Would this still work with a normal Polarizer and ND Filters? I already own a Mattebox with Filters, so just getting a Polarizer would be much easier for me🙂

  4. Awesome! I tried this out on a DSLR shoot this weekend and it worked amazingly – probably the single most useful post I’ve read on your site – thanks for sharing!

  5. Hi Frank!

    Tnx for the awesome post, just wondering, what made you pick the heliopan fader over the geniustech Eclipse for this test, because in your last post about nd faders you were amazed about the eclipse:-)

  6. So I have a Schneider Optics Fader ND. But there are no threads on the front of it. If I put the IR-cut filter behind it (closest to lens) is that going to cause me problems?

  7. Pingback: Improving Dynamic Range with an ND Filter | BIGASSGLASS

  8. Two thoughts:
    Are the highlights polarised light ?
    Very unlikely they would be circularly polarised …
    I think it is because the highlights are de-focussed, so they are less ‘high’.
    Needs more testing …

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