Home alone in the Christmas Eve, I pulled out my Canon 100-400mm f5.6L for some fun. Mounting it on my Mark-X, it's an easy loading indeed.
I'm trying to use my Canon 450D for planet imaging with EOS Camera Movie Record by using its LiveView mode. I'm using the latest version which supports 5x as ROI so that you can move around the chip! That's really great for centering the planet since we have a really huge APS-C chip especially when compared to a 1/4" ToUCam Pro CCD or a 1/3" Lumenera LU070M CCD!
The "motorized focuser" of the Canon 100-400mm is a joy to use, you can even remote control it via USB with software. It's just silent and accurate with the USM, a fantastic experience.
I've tried to use it at 400mm f/5.6 but it's too short for fun, so I jumped up with a Kenko 2x and thus it becomes 800mm f/11.
With the extremely poor seeing tonight, the two major cloud belts were well resolved. So there's a good potential actually. I'm using ISO 400 at f/11, 1/60s. Notice that a regular telescope can do f/25 easily and thus, I believe I will need another 2x to fully unleash its power.