Using an AT4073A as my boom mic. Just wanted to know - when recording interviews, should I switch on the high-pass filter to go from flat freq to low-end roll-off?
You may need to use the low cut to help with wind rumble or handling noise (not a substitute for wind protection (not just foam) and shock mounting). Those rumbles can overload the input on the camera (or mixer) and cause you to record garbage. As oleg says, you can't fix that in post.
150 hz may be a bit high if you don't need it (I usually low cut at 80hz on my 302). You can hear the loss in the voice. Don't use it unless you have to.