In case any of you want to try a gel filter that is supposed to be 'optically correct' for use in front of the lens, vs cutting a cheaper gel that normally are used for lights, Lee makes one for $20 or so. I picked up an ND9 and ND6 from B&H: http://www.bhphotovideo.com/c/product/102709-REG/LEE_Filters_9NDP3_3x3_Neutral_Density_ND.html I've cut numerous Kodak wratten gels over the years. They're definitely not cheap and easily can be damaged or smudged and there's no way of cleaning the filters once that happens. If you're going this route I highly recommend practicing on some sample gels that you can pick up at any photography store. I'm still trying to find the best way to attach the gels onto the lens. So far the best method I'm finding is to unscrew the ring/uv filter. Cut two tiny pieces (few mm's across) of 3m double sided scotch tape on the black part on the lens that says dji and the lens info, then cut a round piece of the gel and place on top. Screw the filter ring back in place. You can get 4 - 5 pieces out of each 3"x3" square and it won't cause any weight difference for the gimbal vs using heavy add-ons. The next thing I need to figure out is how to use a polarizer. Unlike the ND's it would only really help if they can turn so hopefully someone can design a similar threaded polarizer filter that fits on just like the UV filter that's on there now.