Matt tells ya right Sarath. Its a good tool to have in memory.
I have a 7100 & the lowest ISO is 100. Now if your 7200 goes to ISO 50 - you have your light meter. I'd use it in matrix mode & let it do the zone system for you. If it only went down to 100, you could still use it, but for each exposure, you'd need either one stop more open aperture or a shutter speed twice as long - either or - not both.
Have some fun. I think I used my 7100 last Nov. I just enjoy film alot more.