if you squeeze it too tight it pushes the metal ring into the threads, you need to wrap a rubber band around it and put even pressure around the ring as you uncrew. It will come loose, I have had to do it to a few different phantoms and it has always eventually come loose. be gentle so you don't damage your gimbal.
The Polar Pro filters are ok, if you order directly from them you will get a carry case since everyone was complaining (myself included) about the lack of one. I personally never used the ND4 filter and ND8 works great but I hate that I only have 2 ND options in the Polar Pro Set, If you spend more money you can have more ND options. That is where the @Rainbowers set comes into play. I knew if I was going to spend slightly more than $100 on a set of filters I would have to get the rainbowers kit. It comes with 2 graduated filters and you can use 2 different filters at a time. Before I ordered the rainbowers kit I ordered an adjustable ND filter from Amazon. You can twist it and adjust it on the fly which was ideal to me so I could find the best exposure for filming with a shutter speed at 2x my frame rate. I haven't tested the rainbowers filters or the adjustable ND filter yet but I will post a review when I do. Until then, here is a picture of all 3.
I have all of these filters. I don't know how the glass compares, but I can tell you they are all quality products. The only thing I don't like about the SRP filters is that they are very hard to slide on and off the camera. They are just too snug.
This is the variable ND filter I have, I have not had a chance to test it yet as I am having to send my P3P in for service due to a gimbal problem and focus problems. It does weigh 8 grams more than the phantom UV filter so i am guessing it will need to be balanced in the same manner as the rainbowers filters. This is the thread to the rainbowers filters, see post 249 for ordering instructions:
This is hot and miss due to tolerance variations of the DJI filter ring. I still have my first DJI stock filter from my very first P3P. Fits well. It's tight on my new P3P. So I just removed the scratched UV out of the 1st filter and mount my SRPs to it.
