canon 600rx

can I use this flash to gauge the distance between the subject and myself - i.e. - would it tell me how far is the subject from me in feet/meters?

Is there a way my 7D can do the same without the flash?

Depending on your lens, you could focus and then peer down at the lens barrel's distance scale and get an idea. Otherwise, if the 600rx functions like my 430, it'd go like so.

1. Set your flash into ETTL
2. Focus and meter your subject
3. Look at the LCD on the flash head and it should tell you how far the light is going to travel from your flash-head.