I guess what a lot of people would be confused about here is what the difference is between "this is the fire" and "this fire"
Their meaning and that's about it. "Ez a tűz" can be both and we don't seem to be too much bothered by it.
My hungarian girlfriend tells me this should be "Ez az a tűz". Is she right?
"This is that fire"
Girlfriends should always be told that they are right ;)
Apart from this fact, "Ez az a(z)" is how I've been thought to say "this is". But maybe "ez a(z)" is enough to express the same?