Star Trails .... OK I Have to ask

Discussion in 'Astrophotography' started by Fred S, Mar 6, 2014.

  1. Fred S

    Fred S Mu-43 Top Veteran

    Feb 20, 2012
    Fred S
    using the 600 rule to avoid Star trails " 600 / crop factor / marked focal length "
    A star near the horizon moves much quicker in the sky compared to a star near the pole
    So how does the 600 rule work for this :confused:

    thanks in advance
  2. stuartpm3

    stuartpm3 Mu-43 Rookie

    Feb 9, 2014
    The rule is for stars at the celestial equator and for big photo sensors. For micro 4/3 its between 150 and 300. Rather than 600. You need to divide by cos ( declination) away from the equator.


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