If the LogTicks value for a physical axis is non-zero, the major tick marks on that axis will be spaced logarithmically (that is, there will be a constant ratio between the axis values at adjacent major tick marks). An error will be reported if the dynamic range of the axis (the ratio of the largest to smallest displayed axis value) is less than 10.0. If the LogTicks value is zero, the major tick marks will be evenly spaced (that is, there will be a constant difference between the axis values at adjacent major tick marks). The default is to produce logarithmically spaced tick marks if the corresponding LogPlot attribute is non-zero and the ratio of maximum axis value to minimum axis value is 100 or more. If either of these conditions is not met, the default is to produce linearly spaced tick marks.
AST A Library for Handling World Coordinate Systems in Astronomy