Here's my attempt at a piggyback shot of the large meg cloud..Let down by drift problem(see dsi posting)...a bit noisy i know but still...not bad...1 8 min exposure f 2.8 iso 1600 canon 10 d..
It can be offset, but the closer you can get it to the line of your object being imaged the better. The more your alignment is out the closer it needs to be. Though for short images of only a couple of minutes, unless you're a long way out, it shouldn't matter. What are you guiding with?