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Variable ND

Discussion in 'Native Lenses' started by sprinke, Feb 16, 2012.

  1. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    My two fast primes are the 20mm f/1.7 and the 45mm f/1.8.

    I've been thinking of getting a Variable ND filter so I can get nice shallow DOF in bright light with these lenses.

    Do you think this is a good idea: get a 46mm filter (fits the 20) as well as a 37 to 46 mm step up ring so I can use the same filter on the Oly 45?
     
  2. ean10775

    ean10775 Mu-43 All-Pro

    Jan 31, 2011
    Cleveland, Ohio
    Eric
    If all you care about is shallow DOF in bright light for still images, a regular ND filter will achieve the same thing without the image degradation commonly associated with all but the most expensive of the Vari ND filters and a good one will be cheaper. I would just choose the most powerful one you think you'll need, but perhaps others can chime in with specific recommendations.
     
  3. pxpaulx

    pxpaulx Mu-43 All-Pro

    Jan 19, 2010
    Midwest
    Paul
    Agreed, absolutely no point to a variable ND filter - those were made for landscape photography and won't really impact photos when all you need is for the frame to be darker. Using a step down ring and buying 1 filter makes 100% sense.
     
  4. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Agreed also, get a regular ND and a step-up ring.

    The only time a step-up ring doesn't make sense is if you have a bayonet hood on your smaller size and need to use the filter with the hood together. However, adding a screw-in hood to the larger filter size will completely alleviate that problem as well as making the swap easier. ;)
     
  5. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    Thanks for the advice guys. Not sure which ND filter I would need though! :(

    I guess I would figure it out by taking the lens to the same light condition, check the aperture I'm getting, and then subtract the max aperture of the lens? For example, if I'm using the 45mm outside and need to use f/5.6 for good exposure, I would subtract 5.6 - 1.8, so I'd probably need a +4 filter? Does that sound right? Is it better to err on the too dark, or too light side?
     
  6. ean10775

    ean10775 Mu-43 All-Pro

    Jan 31, 2011
    Cleveland, Ohio
    Eric
    More than you need is better than not enough - to a degree. Obviously you don't want it to be so dark that you have to up your ISO higher than you want to in order to let enough light in to get a reasonable shutter speed, but at the same time if its not dark enough, you'll never be able to get to 1.8/1.7 even at ISO 100/200 because you'll top out your shutter speed.
     
  7. starlabs

    starlabs Mu-43 Top Veteran

    856
    Sep 30, 2010
    Los Angeles
    I bought a few 0.6 2-stop filters. With the 1/4000 max shutter, it's been (so far) enough to allow me to shoot wide open with my PL25 at f/1.4 with no issues.

    Edit: Took a look at a few of the pics I took in the above scenario. A few hit the 1/4000 limit due to the base ISO200 of my E-P3. So, I would consider getting an additional 4-stop ND filter in the future for myself as well...
     
  8. meyerweb

    meyerweb Mu-43 Hall of Famer

    Sep 5, 2011
    And an 8 stop filter lets you do some really neat effects with long daytime exposures, to get cloud trails, and blur moving traffic and pedestrians, or water.
     
  9. Your other option is a circular polariser. I think the reduction in light transmission is ~ 1.5-3 stops depending on the rotation angle. It does give an effect beyond that of simply reducing light transmission, but as filters go it is reasonably neutral.