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Thread: Homemade center filter

  1. #1

    Join Date
    Sep 2007
    Posts
    518

    Homemade center filter

    Goofing around with old glop from carbon printing
    dilute, nearly clear coating that covers the filter thinly
    then dropping single drops of increasing density into the center from decreasing heights to form an even dispersion

    How well could that crap work?
    When dry the gelatin layer must be "incredibly" thin but it would have a slightly thicker central area
    or would it have a slightly thicker outer area? Both?
    I can't see it by eye but
    Any chemical that might aid in the evenness?
    I figure taking the glass out of the filter ring would help but please


    someone on here said smoking a piece of glass to produce the effect might work
    reverse printing the fall off onto mylar etc


    just wondering which would produce the best quality easiest




    I tried this as a grad ND on picture frame glass and it works well enough



    not trying to reinvent the wheel
    just playing
    but I'm also never buying a center filter till I can take a photo that will pay for center filter

  2. #2

    Join Date
    Feb 2006
    Posts
    3,113

    Re: Homemade center filter

    Try smoking a filter over a candle.
    One man's Mede is another man's Persian.

  3. #3

    Join Date
    Sep 2007
    Posts
    518

    Re: Homemade center filter

    I included you, man

    but I'm not supposed to play with fire

  4. #4
    Maris Rusis's Avatar
    Join Date
    May 2006
    Location
    Noosa, Australia.
    Posts
    555

    Re: Homemade center filter

    I once made an experimental centre-dark filter from two 75mm diameter spectacle lenses, a +2dioptre and a -2 dioptre. The +2 was dyed dark brown for use in sunglasses. Held together the powers cancel but the centre-dark effect was perfect. Total cost was $50 and the optical quality was ok. Colour neutral? No way!
    Photography:first utterance. Sir John Herschel, 14 March 1839 at the Royal Society. "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..".

  5. #5
    Consulting the pineal gland
    Join Date
    Jan 2009
    Location
    near Taos, NM
    Posts
    204

    Re: Homemade center filter

    You could try dyeing a CR39 resin filter.
    Its not that hard to gradient tint an eyeglass lens, iirc 50% took about a half hour and we had to move it every minute or so to keep it even enough. IIRC (its been years) there was also a bleach that would remove most but not all of the dye. The stuff is used hot, about 180f if I remember right. I believe Cokin uses CR39 as the resin for their filters. Don't expect true color neutrality, there's a reason these things cost...

    Not sure where you'd source the dye but any one-hour eyeglass place would have the stuff and you might talk one into giving you their old stuff when they change it.

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