RF 10-20 f/4 L vs RF 15-35 f/2.8 L...
OK, so the obvious... The 15-35 is faster at f/2.8. The 10-20 is wider, more unique, and if paired with a 24-105 f/4 L will give a photog everything they need between ultra, ultra wide and medium telephoto. It's also more expensive.Not so obvious...?...