Hi Guys

I have a bit of an issue with my copter. If anyone can give me some advice, I would be very grateful.

I am carrying a payload of about 750gram. This includes a GoPro, AV transmitter and bat pack, Xbee and landing gear. When I fly, the copter will launch fine and gain altitude fast, when I back off the throttle to adjust altitude, the copter keeps on dropping as if the bat is low. It will descend until touching down. If I then restart, the proses repeats itself. I dont think weight is an issue, and it does this with all my 3200mA/h cells, so its not power related. The motors, ESC's and props are still standard.

Any settings I am missing or suggestions would be awesome!