Quote Originally Posted by Anbesol
You don't need to purchase APS lens to fit your D80, you could already be getting full frame glass and using it cropped.

What he meant by system was (I think) the range and variety of accessories, and the proprietary standards that tie a lot of gear together.
It is true that I don't HAVE to buy the 'APS' lenses, but they ARE a lot less expensive. But I do agree about the other accessories: I won't have to replace my flash which is dedicated to Nikon because it will also work on a Nikon DSLR with larger sensor.