Just built a 4"F10 refractor tube assembly for under 200 dollars US,and in my haste to see Mars at opposition I assembled the scope without the baffles just a blackened tube the results were quite poor, Mars looked like a boiling cauldron due to stray light in the tube so I added a single baffel and the planets image began to stabilize and some detail could be seen so I installed a full set of baffels and now Mars resolved into a perfect disc at all mags...Bob.