Didn't see or capture Saturn for one year or maybe two years! This time, I am using my Orion 100ED f/9, it's definitely non-stellar with a 40mm Pentax XL, and switching to a 13mm Nagler Type 6 revealed its ring. The ring is closing but it's very contrasty still. Adding a 2x barlows does help to show more detail. Finally, I switched to a 7mm Ortho and it gives the best view, the subtle color variation on the globe is quite apparent. No color error for all magnifications that I tried, it's definitely a great scope!
On defocusing, it shows that at least 20-30% of aperture is blocked by the window frame or the wall, but anyway, it's good enough. I pulled out my DMK and the effect for the partial aperture blocking is now more pronounced since the image is dim even at f/18, I have to go down to 1/8s exposure with medium gain, or 1/15s with high gain.
2340 (GMT+8), slower shutter, low gain:-
2343 (GMT+8), faster shutter, higher gain:-