People are being photographed while mountain climbing or hiking.
A photographer taking photos of hikers.
Just because people are hiking it does not mean they are hikers.  Just because are being photographed it does not mean a photographer is taking photos.
exists e1 x1 x2 x3.(while(e1,x2) & (n_climb(x2) | n_hike(x2)) & of(x2,x3) & n_mountain(x3) & Theme(e1,x1) & v_photograph(e1) & n_people(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_take(e1) & of(x3,x4) & n_hiker(x4) & n_photo(x3) & (x1 = x2) & n_photographer(x1))