Mine has become my fave lens…and to date I almost always have the 1.4TC on it with the 2.0 in the bag…but based on a couple of recent videos from Hudson Henry…who is with Steve my favorite guru…I’m trying it with Fn1 on the Z9 set to change to DX mode and leaving the tC off unless I need to get more reach than 600…that gains a stop of light and minimizes the admittedly slight IQ hit. For my output which is all screen…the 19MP or whatever DX is on the Z9 is probably plenty…but I haven’t gone on an outing yet to try both combos on the same subject to see if it makes a difference beyond the 1 stop.