Suavi,
You've brought up an important point in your last post about being able to view the fainter moons with very short focal length eyepieces.
Most of us will be familiar with the "limiting magnitude" of a given aperture thing. The trick with this though is that it requires high power in order to achieve this. Higher magnification helps improve contrast, and so helps bring out the fainter stars, and also nebulous details, including details in galaxies. This is an old observer's trick to help bring out faint galaxies and even details in brighter ones
Don't be shy about increasing the magnification sometimes.
This is why you couldn't see the fainter saturnian moons with long focal length eyepieces.
Alex.