def convert(angle):
    """
    Convert an ephem angle (degrees, minutes, seconds) to
    an EXIF-appropriate representation (rationals)
    e.g. '51:35:19.7' to '51/1,35/1,197/10'
    Return a tuple containing a boolean and the converted angle,
    with the boolean indicating if the angle is negative.
    """
    degrees, minutes, seconds = (float(field) for field in str(angle).split(":"))
    exif_angle = f'{abs(degrees):.0f}/1,{minutes:.0f}/1,{seconds*10:.0f}/10'
    return degrees < 0, exif_angle