hello ian firstly let me say i envy your astro pics
the first and only dslr i have ever had is my 60da and for the year i have had it i have tried just about every combination of exposure and iso, and i concur with mr bradley that my sweet spot i have found to be iso 800 and between 180s and 240s exposures in mount hawthorn
i too use the f6.3 reducer plus an LP filter which i dont think you use(?)
pat
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