A few nights ago I put the 3 x Sky 90s back on the California nebula for a total of 21 x 20-minute subs. I had already captured 33 x 20-minute subs, so I had a grand total of 18 effective hours on the nebula using 20-minute sub-exposures. Shows the power of the array as this was only 6-hours total imaging time 🙂
And here is the result: