Iceland to France is Schengen-internal, so you won't need to cross immigration controls.
However, you can't walk between terminals 1 and 2 at CDG.
There are airside transfer shuttles, but at Terminal 1 they serve only the non-Schengen transit area which you won't reach with your itinerary.
You'll need to go landside at terminal 1 and then take the CDGVAL peoplemover to terminal 2F and pass through security again. CDGVAL should not take more than 15 minutes, including wait time, but there are scattered reports of occasional very long security lines. With a non-guaranteed connection I would want to leave terminal 1 at least 1½ hours before scheduled departure, and I wouldn't feel halfway comfortable unless I had 2½. Add another 20 minutes for flights departing from terminals 2E (rows L and M) and 2G as they require another bus or peoplemover transfer after security.