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L.C.W. Fader ND: Scratchy / Striated Bokeh!?
  • SangyeSangye

    I just made another post in which I asked for recommendations for a 4x4 neutral density solution, given certain parameters. Please see that thread here: http://personal-view.com/talks/discussion/4806/4x4-nd-filters-fixed-set-or-double-polarizers-as-variable-nd#Item_1

    However, I feel that the issue that I had with my previous ND warranted a separate thread, to discuss an interesting phenomenon: bokeh striation.

    I'm not exactly sure what causes it, but this is what it looks like:

    Note the "scratchiness" inside the bokeh blobs, particularly in the brightest OOF areas.

    I have only ever had this problem while using my L.C.W Mark II variable ND filter, and I haven't seen it in many other videos, so I don't think it's an issue common to all variable ND filters.

    It doesn't always happen while using this filter, either. It seems to happen most in high-contrast situations with bright points of light in the OOF area.

    Has anyone else run into this problem, if so, can you say anything about what lens and filter you were using at the time?

    Thanks!

  • 7 Replies sorted by
  • SangyeSangye

    Another example:

  • RamboRambo

    What lens are you using?

  • SangyeSangye

    @Rambo The first was shot on a thoriated M42-mount Pentax Super-Takumar 55mm f/2, and the second was shot on a Voigtländer 25mm f/0.95.

  • RamboRambo

    I've seen this with my Vari ND in similar green/brown bush backgrounds as both of your videos and i always thought it was these backgrounds that caused the problem as it's not happened with plain or less busy backgrounds. I wonder if it's the green tint from the polarizers that causes this or if it's related to the horrible effect you get when you point a VariND at tinted car window?

    The only lenses i have that do this WITHOUT VariND are Nikon DX G series, they have OOF areas like above.

  • RamboRambo

    Only other time i've noticed this is when the VariND is almost at max and there is a "cross effect".

    Seb Farges uses VariND's on all his videos with wide open lenses, i've not seen this effect on his videos that i can remember. https://vimeo.com/sebfarges

  • RRRRRRRR

    Isn´t this a property of vari nd´s built from twin polarizers? If so, I´d expect the effect to only be present at certain focal points, and in certain lighting. A bit like if you get raindrops on your lens, they might only show in the bokeh.

  • RamboRambo

    Could be the focal points, the OOF blob above the mans shoulder in the 2nd video is very "striated" but the one above his head is clean and nicely blurred.

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