I just ran across this 3DR Spec page on the Solo. Here's a quote from its specs on the Gimbal (found near the bottom.) "Fully compatible with 3DR Solo and GoPro HERO3+ and HERO4; camera charging and stabilization only with HERO3."
I purchased the HERO4 Black for the Solo and now they're saying it won't stabilize??? (not happy)
I purchased the HERO4 Black for the Solo and now they're saying it won't stabilize??? (not happy)