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    Re: Daytime Venus Rising Dip Short
    From: Bill B
    Date: 2012 May 03, 18:54 -0400

    On 5/3/2012 6:20 PM, Greg Rudzinski wrote:
    > I used an older 10 MP Canon Rebel with an adaptor to take a 1970's era
    > 200mm prime Pentax lens. The filter for the first photo had astronomy
    > mylar film over the lens (didn't work that good). The second image used
    > a pair of polarizers then the settings were at F22, ISO 100, and
    > 1/4000s. In iPhoto the image was cropped then adjusted for contrast,
    > exposure, etc.
    Most consumer or prosumer digital SLR's use an array smaller than the
    24x36 image on 35mm film, so the the effective focal length is about
    x1.4 for most brands and x1.5 for Nikon.  I doubt if full size arrays
    were an option (maybe for Canon) when you purchased your Pentax.  If you
    did purchase a full-size array back then you would most likely remember
    as the camera body would cost about the same as a new mid-sized car.
    I have used the double polarizers for long exposures of waterfalls etc.,
    but used a stack of neutral density (ND) gels for an eclipse.  Never
    occurred to me to try the polarizing filters. Duh!  Thanks.
    Bill B

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