I would mono and lx mod your 900nc if your tight for cash. I would be also hunting down a used dsi pro or getting a qhy5 ect, as there tends to be alot of work and frustration getting guiding working well with a 900nc, not to say it can't be done or anything though. Thanks peter for the saturation info in phd didn't know it had it
I herd you can also make the focus off to help with the sat issue even though its great to do to find the centroid anyhow. Having a hell of a time here with flexture issues with the dsi's weight and just built a st80 up with a very tough focusing system and are waiting on these dam clouds in melbs to clear to see if i've got the system finally working sweet.