Hello. I have an order of Skywatcher Explorer 250PDS and it should arrive within a month or so. I also have a Nikon D40 camera and I was wondering what kinf of adapter must I purchase to make sure it will work with my new 'scope. Are there more than one type of T-ring adapters for camera/telescope combination or are they all of same standard? Would this thing do? I never had one and just want to be 100% sure it will work fine and that I don't buy something that will not work.