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Interesting -- variable ND Filter

Discussion in 'Accessories' started by WT21, Aug 1, 2011.

  1. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    Only in 77mm and 82mm though. I use a 3 stop ND and never needed more but I agree that iI certainly could find uses for it. If they make a 58mm version I'm in.

    Gordon
     
  2. Promit

    Promit Mu-43 All-Pro

    Jun 6, 2011
    Baltimore, MD
    Promit Roy
    10EVs on the top end. Can I photograph the sun yet?

    P.S. I am not joking.
     
  3. Sammyboy

    Sammyboy m43 Pro

    Oct 26, 2010
    Steeler Country
    Not with anything using an optical viewfinder, that's for sure !!!!
     
  4. Promit

    Promit Mu-43 All-Pro

    Jun 6, 2011
    Baltimore, MD
    Promit Roy
    Yes, that would probably be best to avoid.
     
  5. Luke

    Luke Mu-43 Hall of Famer

    Jul 30, 2010
    Milwaukee, WI
    Luke
    • Like Like x 1
  6. Djarum

    Djarum Super Moderator

    Dec 15, 2009
    Huntsville, AL, USA
    Jason
    Hoya has one too. Stack a linear and circular polorizer and you have a variable nd filter.
     
  7. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    That's what I was thinking, just find two old linear polarisers with threads to match and turn to suit ...
     
  8. Djarum

    Djarum Super Moderator

    Dec 15, 2009
    Huntsville, AL, USA
    Jason
    Yes, but two linears stacked might mess up some cameras. Keeping the circular closest to the front element and the linear on top.

    Using Crossed Polarizers for a Variable ND Filter | Digital ImageMaker

    I actually use a version of these(cost me about 20 bucks) for viewing the moon through a telescope.

    Only concern I'd have is that adding more glass surfaces instead of just one ND filter could add flare or ghosting.
     
  9. zettapixel

    zettapixel Mu-43 Veteran

    470
    Aug 12, 2010
    NY
  10. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    Good reading Djarum, thanks for the link.
    Stuff worth knowing!
    (Although by the by for CDAF, important for phase detect is my uneducated guess.)
     
  11. RobWatson

    RobWatson Mu-43 Hall of Famer

    Pretty close but probably 13-14 EV is more appropriate. You will want that over the whole aperture. An interesting thing to try is a 0.3 to 1 Angstrom wide filter centered on the H-alpha line (656.3nm) but you are going to want to also use a hefty ND filter as well.

    For seriously photographing the sun best to use a dedicated and specialized solution (Coronado PST 0.5A DoubleStack H-Alpha Telescope - OPT Telescopes)

    I've found the 14EV (5 O.D.) ND type filters are fine a a rough view of surface granularity and decent resolution of sun spots. The H-alpha filter gives remarkably different details on the 'active' objects as well as coronal detail.


    I would never suggest using a variable ND filter to view or image the sun as permanent damage will result if even the slightest thing goes wrong (and it will).