|
There is a big difference in focal length between those two scopes! Short focal length scopes are much more tolerant of guiding irregularities than long focal length ones. And those budget RCs are notorious for collimation and focuser shifting problems. Of course the light is being blocked in the RC by that large central obstruction. Start with fundamentals, is the RC properly collimated with your image train installed on it? Honestly, i would not worry about a flattener on that RC just yet, they are supposed to be a flat field design, at least flat enough that its not the main cause of your problem.
|