Three weeks ago, I tried installing a 5.4 mm lens, that is my lens of choice because it has a field of view of only 64 degrees, the stock lens has a field of view of 98 degrees...the narrow the field of view the less distortion. (I've installed about 10 of those on GoPros when I flew Phantoms) However the 5.4 will not focus in the lens mount...you need a deeper mount. Removing the old mount is problematic because of the epoxy glue they used and there are also 4 hair thin wires connected to a board smaller than a postage stamp which controls the gimbal which is very delicate. Each of those wire is finely soldered with a tiny dot of solder So I've settled for now with 3.9mm lens which has a field of view of 84 degrees. I like to fly low and close to my subjects and this lens allows me to have the image closer at a greater distance with less distortion. I got my 3.9mm lens from Skydrones USA in Iowa.