I've looked into that Steven, and intend to buy Registar for that purpose.. Also for the purpose of creating mosaics, and for combining data taken days or even weeks apart where the camera angle may have been rotated etc.. I do plan to stop using data from different focal length systems, I've just not had any colour data to work from with this scope yet.. So I've been using colour data from previous scopes. This has involved manual resizing and rotation, followed by alignment, which as you can see in the image, is not a fool proof method
Cheers.
Alex.