exaclty .. but xt + 75-300 combination dosent seem a really big or scary combination

Depends 'big to who' 
Canon touts the light weight of their 400 Diffractive Optics lens. "LIGHT" also really depends who is looking at it...to anybody with an appreciation of their big supertele's, the DO is light.. to anybody used to the small glass, the DO is big, WHITE, and HUGE, regardless 




