10-13-2010, 01:36 PM
I just thought - by changing the distance to the subject by 1.5x, DOF decreased by 1.5x as well (11.3m vs 7.5m). However as DOF is based on the hyperfocal distance which uses f^2, DOF / focal distance relation is not linear - you can't just multiply the focal length of the lens by 1.5x (75mm as in your example) to get the FF DOF equivalent. If it makes sense :-)