With a 5D Mark III,I tested out my 16-35mm at a cathedral in New York. Shooting down the nave on a tripod at 16mm pushed everything too far away. I used my 24 T/S which I liked better, especially the shift function for the columns. But I got a narrower angle and less of the sides of the nave.
Two questions I have. First, can I use the 24mm T/S tilt function to get three shots, middle, left and right, then merge them in PS for a wider shot of the nave? Will that look natural or distorted?
Second, should I simply rent a 17mm T/S to get a wider point of view in the first place without stitching?
Or what other suggestions do you have?

